CA1144105A - Process for reducing the sulphur content of coal - Google Patents
Process for reducing the sulphur content of coalInfo
- Publication number
- CA1144105A CA1144105A CA000357855A CA357855A CA1144105A CA 1144105 A CA1144105 A CA 1144105A CA 000357855 A CA000357855 A CA 000357855A CA 357855 A CA357855 A CA 357855A CA 1144105 A CA1144105 A CA 1144105A
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- CA
- Canada
- Prior art keywords
- coal
- pyrite
- particles
- component
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C7/00—Separating solids from solids by electrostatic effect
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L9/00—Treating solid fuels to improve their combustion
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S44/00—Fuel and related compositions
- Y10S44/904—Method involving electric or wave energy
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Electrostatic Separation (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
After pulverizing to minus 200 mesh, a mixture of coal and pyrite particles is passed through an A.C. silent corona discharge in the presence of a reactant gas.
Simultaneously; the particles are de-agglomerated and an electrical or magnetic difference between them is enhanced.
Thereafter, the pyrite is separated from the coal. The effectiveness of the pulverizing step in separate pyrite particles from the coal matrix, especially small-size particles approximately 50 micrometers and less, is enhanced by pretreating the coal with a chemical comminutant. One example is a solution of ammonia, used to presoak the coal for a short time, at, for example, atmospheric pressure and ambient temperature.
After pulverizing to minus 200 mesh, a mixture of coal and pyrite particles is passed through an A.C. silent corona discharge in the presence of a reactant gas.
Simultaneously; the particles are de-agglomerated and an electrical or magnetic difference between them is enhanced.
Thereafter, the pyrite is separated from the coal. The effectiveness of the pulverizing step in separate pyrite particles from the coal matrix, especially small-size particles approximately 50 micrometers and less, is enhanced by pretreating the coal with a chemical comminutant. One example is a solution of ammonia, used to presoak the coal for a short time, at, for example, atmospheric pressure and ambient temperature.
Description
1~5/ 1~44~
!~/jm 2Owing primarily to environmental legal requirements, 3 a copious coal resource of the United States of America is 4 not being used to provide the share of the Nation's energy supply that`it could provide. Much of the available coal 6 contains sulfur, from 2-6~ by weight, levels which have by 7 law been declared intolerable. Many efforts have been made 8 to find ways to remove the sulfur content, or at least to 9 reduce it to an acceptable level but, so far, it has not been done. The problem is described in a paper by Sabri 11 Ergun and Ernest H. Bean entitled "Magnetic Separation of 12 Pyrite from Coals", published by the Bureau of Mines (1968), 13 United States Department of the Interior, Report of 14 Investigations 7181. The authors propose certain approaches employing dielectric heating of coals at selected frequencies 16 to enhance the paramagnetism of pyrite by selectively heating 17 the pyrite to transform some of it into pyrrhotite, which has 18 nearly 1,000 times the magnetic susceptibility of pyrite.
19 The authors state (at page 23) "In this type of heating, pyrite need not be crushed to be reactive; indeed, the opposite 21 is true, that is, the coarser the pyrite, the more readily it 22 will be heated. Crushing process necessary to liberate 23 pyrite can be done after dielectric heating". However, this 24 does not address the treatment of those coal types in which the pyrite exists in particle sizes smaller than, for example, 26 50 micrometers, and in some cases as small as 10 micrometers.
27In a more recent paper entitled "Significance of Colloidal 28 Pyrite Distribution for Improving Sulfur Determinations in 29 Coal" by R.T. Greer, Department of Engineering Science and Mechanics and Engineering Research Institute, Iowa State University, Ames, Iowa 50011, published in Proceedings of the International Symposium of Analytical Chemistry in the Exploration, Mining and Processing of Materials, Johannesburg, Republic of South Africa, 23-27 August 1976, at pages 171-174, 1976, it is stated that pyrite is the major source of sulfur in coals, and that in order to free the sulfur-bearing phases from the organ-ic matrix of the coal, it is important to require that the coal be pulverized to particles smaller than will pass through a standard 400 mesh sieve. I
have found that in many different types of coal, especially coals enclosing pyrite particles in sizes as small as or smaller than 50 micrometers, crushing or pulverizing the coal may not be sufficient to physically separate enough of the pyrite from the coal matrix to enable the sulfur content of the coal to be reduced to an acceptable level. I have found also that industrial processes and apparatus that are currently available for separat-ing components of a mixture of particles have not reached the capability of handling coal that is pulverized to less than 200 mesh. Coal which is pulverized so fine resembles dust; it tends to form clumps after being pulverized and, if successfully de-agglomerated, it tends to form dust-like clouds in high tension separator apparatus which otherwise appears to be highly desirable for performing the end step of separating the pyrite from the coal.
GENER~L DESCRIPTION OF THE INVENTION
The invention provides a process for reducing the sulfur content of coal comprising the steps of pulverizing the coal so as to free a substan-tial percentage of the pyrite component physically from the coal component, passing a mixture Of the particles of the coal and the pyrite through an A.C. silent corona discharge so as to reduce adhesion by electrostatic forces and thereby de-agglomerate substantially all the particles, and there-after separating the components one from the other.
Thus, the process comprises as a first step pulverizing the coal, preferably to minus 200 mesh, so as to provide a mixture of coal and pyrite particles in which the majority :~R/~m~ 1144~05 1 of the pyrite particles are physically freed from the coal
!~/jm 2Owing primarily to environmental legal requirements, 3 a copious coal resource of the United States of America is 4 not being used to provide the share of the Nation's energy supply that`it could provide. Much of the available coal 6 contains sulfur, from 2-6~ by weight, levels which have by 7 law been declared intolerable. Many efforts have been made 8 to find ways to remove the sulfur content, or at least to 9 reduce it to an acceptable level but, so far, it has not been done. The problem is described in a paper by Sabri 11 Ergun and Ernest H. Bean entitled "Magnetic Separation of 12 Pyrite from Coals", published by the Bureau of Mines (1968), 13 United States Department of the Interior, Report of 14 Investigations 7181. The authors propose certain approaches employing dielectric heating of coals at selected frequencies 16 to enhance the paramagnetism of pyrite by selectively heating 17 the pyrite to transform some of it into pyrrhotite, which has 18 nearly 1,000 times the magnetic susceptibility of pyrite.
19 The authors state (at page 23) "In this type of heating, pyrite need not be crushed to be reactive; indeed, the opposite 21 is true, that is, the coarser the pyrite, the more readily it 22 will be heated. Crushing process necessary to liberate 23 pyrite can be done after dielectric heating". However, this 24 does not address the treatment of those coal types in which the pyrite exists in particle sizes smaller than, for example, 26 50 micrometers, and in some cases as small as 10 micrometers.
27In a more recent paper entitled "Significance of Colloidal 28 Pyrite Distribution for Improving Sulfur Determinations in 29 Coal" by R.T. Greer, Department of Engineering Science and Mechanics and Engineering Research Institute, Iowa State University, Ames, Iowa 50011, published in Proceedings of the International Symposium of Analytical Chemistry in the Exploration, Mining and Processing of Materials, Johannesburg, Republic of South Africa, 23-27 August 1976, at pages 171-174, 1976, it is stated that pyrite is the major source of sulfur in coals, and that in order to free the sulfur-bearing phases from the organ-ic matrix of the coal, it is important to require that the coal be pulverized to particles smaller than will pass through a standard 400 mesh sieve. I
have found that in many different types of coal, especially coals enclosing pyrite particles in sizes as small as or smaller than 50 micrometers, crushing or pulverizing the coal may not be sufficient to physically separate enough of the pyrite from the coal matrix to enable the sulfur content of the coal to be reduced to an acceptable level. I have found also that industrial processes and apparatus that are currently available for separat-ing components of a mixture of particles have not reached the capability of handling coal that is pulverized to less than 200 mesh. Coal which is pulverized so fine resembles dust; it tends to form clumps after being pulverized and, if successfully de-agglomerated, it tends to form dust-like clouds in high tension separator apparatus which otherwise appears to be highly desirable for performing the end step of separating the pyrite from the coal.
GENER~L DESCRIPTION OF THE INVENTION
The invention provides a process for reducing the sulfur content of coal comprising the steps of pulverizing the coal so as to free a substan-tial percentage of the pyrite component physically from the coal component, passing a mixture Of the particles of the coal and the pyrite through an A.C. silent corona discharge so as to reduce adhesion by electrostatic forces and thereby de-agglomerate substantially all the particles, and there-after separating the components one from the other.
Thus, the process comprises as a first step pulverizing the coal, preferably to minus 200 mesh, so as to provide a mixture of coal and pyrite particles in which the majority :~R/~m~ 1144~05 1 of the pyrite particles are physically freed from the coal
2 matrix, and as a second step applying a silent corona A.C.
3 discharge to the mixture in the presence of a gas to separate
4 the particles each from the other so as to de-agglomerate the mixture whe~eby to provide a mixture in which the surfaces of 6 substantially all the particles are accessible for contact 7 treatment. The A.C. corona "silent discharge" ionizes the 8 gas between the electrodes, creating a large number of both 9 positive and negative ions in the gas. This "silent discharge"
also converts a fraction of the gas molecules into nascent 11 atoms of the gas. Presence of coal and pyrite particles in 12 the ionized gas discharges any electrostatic charge on the 13 particles. If the gas is capable of reacting with coal or 14 pyrite, the ionized gas molecules react with the surfaces of the pyrite or the coal particles, converting the selected 16 substance to another compound. For example, hydrogen in the 17 gas will react with iron disulfide (pyrite) converting the 18 surface layer of this substance into iron and the sulfur into 19 a very small quantity of hydrogen sulfide gas. The iron is both electrically highly conductive, and strongly magnetic.
21 This process step alters substantially all the pyrite 22 particles to a depth of at least one molecule to a new chemical 23 form characterized by enhancement of at least one of the pre-24 existing differences in magnetic susceptibility and electrical conductivity between the pyrite and the coal components of 26 the m xture. The process thereafter, in a third step, employs 27 one or both of these enhanced property differences to improve 28 separation of said components one from the other.
29 The step of pulverizing coal containing pyrite particles in the range 50 micrometers or smaller may fail to separate ~5/
;/1/7n9- ~144105 1 enough of the pyrite component from the coal component to 2 alLow subsequent steps of the process to achieve the required 3 sulfur-content reduction. In such cases pulverizing the 4 coal to even smaller sizes than minus 200 mesh may, instead, bring about`increased difficulties in handling the smaller-6 mesh powders that will be produced. I have found that certain 7 chemicals may be used to weaken the bond between the smaller-8 size pyrite particles and the coal matrix prior to the 9 crushing or pulverizing step, after which the effect of the pulverizing step is increased so that pyrite particles as 11 small as 37 micrometers can be physically separated from the 12 coal matrix. For example, if a sample of coal of this type 13 is wetted in an aqueous solution of ammonia or potassium 14 hydroxide for a few hours at atmospheric pressure and ambient temperature, and then dried, the step of pulverizing this 16 sample to minus 200 mesh will achieve increased physical 17 separation of the pyrite component from the coal component.
18 In a preferred process, the final step is performed in 19 a high tension separator, using a process heretofore generally called "electrostatic separation". The term "electrostatic 21 separation" as used in this specification is intended to have 22 the scope of meaning thatis ascribed to it in "Chemical 23 Engineers' Handbook", Robert H. Perry and Cecil H. Chilton, 24 Editorial Directors; 5th Edition 1973, in the article entitled "Electrostatic Separation" at pages 21-62 to 21-65 -- McGraw-26 Hill Book Company, l~ew York, N.Y.
~5/
i2/79 1~441~5 1 DETAILED ~ESCRIPTION OF THE INVENTION
2 The invention is further described with reference to 3 the accompanying drawings, in which:
4 FIG. 1 is a block diagram generally illustrating the invention; `
6 FIG. 2 illustrates the preliminary step of chemically 7 weakening bonds between pyrite and coal components; and 8 FIG. 3 illustrates a silent discharge device for 9 deagglomerating the pulverized mixture of pyrite and coal.
Figure 1 illustrates in a general way the process of the 11 invention. As illustrated, the process comprises three steps, 12 each of which is susceptible of being performed in a variety 13 of ways.
14 In Step 1 the coal is pulverized to -200 mesh. It is now known that pyrite is the major source of sulfur in ~oals, 16 and that pyrite can be distributed in coals on a scale finer 17 than 50 micrometers (~m). In order to separate the particles 18 of pyrite physically from the coal matrix in which they are 19 bound, the coal must be pulverized to -200 mesh or finer.
However, coal that is pulverized so fine is difficult to 21 handle. In a gaseous medium, such as air, the motions of 22 the very small particles of both coal and pyrite, many of 23 which have essentially the same effective aerodynamic diameters, 24 are governed essentially by Stokes' Law defining resistance to 25 motion, 26 R= 6~nav 27 where "n" is the fluid viscosity, "a" is the radius of the 28 particle (sphere), and "v" is the velocity of the particle.
29 Mass is not relevant at the small particle sizes that are present, with the result that th~ particles of both coal and ~45/
~I/2R/7r9 ~ 1~44~0S
1 pyrite are easily carried or scattered together throughout 2 an ambient gaseous environment and, conversely, one is not 3 separable from the other by the force of gravity alone.
4 Once the coal and pyrite are pulverized to the size range required to free a substantial percentage (i.e.: the 6 majority) all of the pyrite physically from the coal, these 7 two components can be differentiated in many ways, so as to 8 enable one component to be separated from the other in 9 subsequent process steps. More particularly, the next step in the process, Step 2, involves the conversion of pyrite ll into a form capable of either magnetic or electrostatic 12 separation from the coal. As it concerns the former, magnetic 13 separation, pyrite, an essentially non-magnetic substance, can14 be converted into a magnetic material by thermal means (some of which are known), or by chemical means. As it concerns the 16 latter, pyrite is relatively more conductive, electrically, 17 than is coal, and this difference can be enhanced by chemical 18 means, or by electrical means, or both acting together, so as 19 to render the pyrite functionally far more conductive, electrically, than is the coal, and thereby more easily capable 21 of separation from the coal by electrostatic means.
22 Magnetic separation of Pyrite from Coals is the subject 23 of a paper bearing that title by Sabri Ergun and Ernest H. Bean, 24 published by the Bureau of Mines (1968), United States Department of the Interior, Report of Investigations 7181. The 26 authors point out that some of the pyrite is converted into 27 ferromagnetic compounds of iron when heated to temperature 28 greater than 500C. Dielectric heating of coals in the Ghz 29 frequency range is suggested as the most feasible method of enhancing the paramagnetism of pyrite. Selective heating of R/~t ~4~
1 the pyrite was recognized in this report. However, the 2 heating times were such (up to 30 minutes in one example) 3 that the coal was also heated to a substantial degree, 4 requiring prohibitive total energy input. This is borne out in N.T.I.S. Report No. PB 285-880.
6 According to the present invention, the paramagnetism of 7 pyrite particles is more economically enhanced by chemically 8 or electrically transforming the surfaces of the pyrite 9 particles into compounds that are more magnetic than iron disulfide (pyrite). This is done chemically, for example, in 11 a treatment of pyrite and coal with halogen gases or the 12 vapors of their acids, such as hydrochloric, hydrobromic or 13 hydroiodic, so as to transform the pyrite particle surface into 14 ferrous or ferric chloride, bromide, or iodide. These compounds, in addition to being more magnetic than iron disulfide, are 16 less expensive to produce than pyrrhotite, the compound which is 17 produced by heating of the pyrite.
18 The surface chemistry of pyrite particles can be 19 electrically altered with an A.C. silent corona discharge.
Recombinations of ions on the surfaces of the particles will 21 result in high local temperatures ~as in corona nitriding of 22 steel) which, if carried out in the presence of an appropriate 23 gas or gasses, will in turn effect a desired chemical reaction.
24 A reactive gas may be introduced along with the pulverized coal and pyrite, between Step 1 and Step 2, as is indicated in 26 Figure 1.
27 In each of these examples, it is the surface of each 28 pyrite particle that is transformed into a compound or compounds 29 that are more magnetic than iron disulfide. It is necessary only to convert a shallow surface layer of each pyrite particle ~-~5/
:i~/jm_ ~2/79 1144i~5 1 to a more magnetic chemical, and this is an energy-saving 2 feature of the invention. It is presented also in the 3 following examples of steps for converting the pyrite into a 4 form that ismore capable of electrostatic separation from S coal.
6 Electrostatic separation of one type of particle from 7 another is possible even when the resistivities are as close as 8 within two or three orders of magnitude. This is sometimes the 9 difference between the electrical resistivities of pyrite versus coal, the pyrite being inherently more electrically 11 conductive than the coal. Electrodynamic separators 12 (employing charging by ion bombardment) are commercially 13 available which can separate particles having a ratio of 14 electrical conductivities approximately five or six orders of magnitude. It is necessary only to convert a shallow 16 surface layer of each pyrite particle to a highly conductive 17 chemical in order to render the pyrite particles functionally 18 far more conductive than are the coal particles; that is, to 19 enhance the pre-existing difference in the electrical conductivities of the two materials.
21 In theory, the enhanced-conductivity surface layer on 22 each pyrite particle need be only a molecule or so in depth.
23 This means that a reaction can take place nearly instantaneously, 24 and it is within the scope of this invention to effect such a reaction at any convenient time after the coal/pyrite mixture 26 leaves the pulverizer.
27 According to the invention, the electrical conductivity 28 of pyrite particles can be enhanced through electrical means 29 combined with chemical means, by passing the pyrite in the form of finely-divided particles, preferably carried in a reactant _g_ R~jn~
,'2/79 i~44~05 1 gas or vapor, between electrodes at least one of which is 2 insulated by a suitable dielectric, and applying between the 3 electrodes an A.C. voltage sufficiently high to cause a 4 silent corona discharge, and thereby create both positive and negative ions in the carrier gas (See Fig. 3). Recombinations 6 of ions on the surface of the pyrite particles result in high 7 local temperatures which if effected in the presence of a 8 reactant carrier gas or vapor will in turn promote or 9 accelerate desired reaction or reactions with such gas or vapor. The recombinations of ions will take place on the 11 surfaces of both the pyrite particles and the coal particles, 12 and intense local heating of these surfaces will result in 13 accelerated chemical reactions between the carrier gas and 14 one or both materials -- the pyrite and/or the coal. The carrier gas or vapor ought therefore to be chosen so as to 16 favor the desired reaction with the pyrite and to avoid or 17 minimize a reaction with the coal.
18 The surfaces of the pyrite particles can be converted 19 into an electrically more conductive compound by reacting the coal/pyrite mixture with chlorine gas, for example just after 21 the mixture leaves the pulverizer, so as to transform the 22 surface layer into ferrous and/or ferric chloride.
23 I have found in working with coal pulverized to minus 200 24 mesh that the coal particles tend to agglomerate, and form clumps. This tends to frustrate any following process step 26 which requires access to the surface of the particles (e.g.:
27 surface conductivity enhancement in the pyrite particles by 28 chemical means, or particle separation in apparatus which 29 depends upon charging the particles by ion bombardment). I
have found, further, that the particles of a -200 mesh mixture ~45/~ ~44~
IR/jnl_ 1 of coal and pyrite are de-agglomerated by passing the mixture 2 through an A.C. silent discharge following the pulverizing step 3 (Step 1). This step of de-agglomerating the particles of the 4 mixture provides access to the surfaces of substantially all the particles, and greatly increases the opportunity to enhance 6 the pre-existing electrical and/or magnetic difference between 7 pyrite and coal, and hence the opportunity to succeed in 8 separating the sulfur-bearing pyrite particles from coal particles.
9 Thus, Step 2 of the process of this invention simultaneously de-agglomerates the mixture of pyrite and coal particles and 11 more greatly enhances a pre-existing difference in their relative 12 electrical conductivity properties and/or their relative magnetic 13 susceptibility properties. Step 3 of the process, which can 14 be performed in any of a variety of known ways, is thereby rendered more effective, and improved.
16 Referring to Figure 2, the bond between pyrite particles 17 and coal matrix is weakened chemically in a preliminary step, 18 block 10, taken prior to Step 1 of the process as described 19 with reference to Figure 1. This preliminary step has been found effective to enhance the subsequent physical separation 21 of the pyrite component from the coal component of a bituminous 22 coal sample in which the pyrite exists in sizes down to about 23 50 micrometers. As an example, a quantity of coal containing 24 3.11% pyritic sulfur was treated with a chemical comminutant, in this example an aqueous solution of 29% ammonia at atmospheric 26 pressure and ambient temperature for a few hours, and then dried, 27 after which it was pulverized in a hammer mill to minus 200 mesh.
28 The pulverized sample was then treated with Step 2 and electro-29 statically separated in Step 3. The coal recovered after Step 3 had a sulfur content of 0.95%. The pyrite sulfur content was ~45/
/2/79 1~4410S
1 reduced 75~.
2 In Figure 3, a dielectric tube 20 (made, for example, 3 of "Pyrex" glass) has an electrically conductive first 4 electrode 21 on its outer surface, and an electrically S conductive second electrode 22 axially located within it.
6 The second electrode can be supported by any suitable holding 7 means (not shown) presenting the smallest possible impediment 8 to flow of the gas and particle mixture. Alternatively, the 9 tube 20 can have two outer electrodes on opposing outer surfaces, in which case the tube walls covered with the 11 electrodes should preferably be flat so that the electrodes 12 will be evenly spaced along the path through which the gas 13 (or vapor) and particle mixture flows. A pair of terminals 14 23, 24 are connected one to each electrode 21, 22, respectively, and an A.C. high voltage approximately 25,000 volts at a low 16 current approximately 1 milliampere is applied across these 17 terminals to produce a silent corona discharge between the 18 electrodes. The gas (or vapor) and particle mixture is passed 19 through this A.C. siient corona discharge, thereby to ionize the gas (or vapor) so as to promote a reaction between the gas 21 (or vapor) and at least the pyrite component in the coal and 22 pyrite mixture, with the results that are described above.
23 The effect of the A.C. silent corona discharge, whether 24 or not a reactant gas or vapor is present, is to deagglomerate the particles in the coal and pyrite mixture. When a mixture 26 pulverized to 200 mesh is passed through the tube 20 and 27 suitable A.C. voltage is applied at terminals 23, 24, the 28 particles execute rapid motion back and forth between the 29 electrodes 21, 22, and transverse to the direction of their passage between the electrodes, so much so that the interior o~4~_~.k ~4~//m~ ~441~
i2/79 1 of the tube becomes clouded with moving particles and blocks 2 substantially the light that would otherwise pass through the 3 tube. The output from the tube is a deagglomerated mixture 4 of coal and pyrite. When a reactant gas is also present, the pyrite h'as been altered to enhance its electrical and/or 6 magnetic properties, as is described above. This output is 7 supplied to separating means in Step 3.
also converts a fraction of the gas molecules into nascent 11 atoms of the gas. Presence of coal and pyrite particles in 12 the ionized gas discharges any electrostatic charge on the 13 particles. If the gas is capable of reacting with coal or 14 pyrite, the ionized gas molecules react with the surfaces of the pyrite or the coal particles, converting the selected 16 substance to another compound. For example, hydrogen in the 17 gas will react with iron disulfide (pyrite) converting the 18 surface layer of this substance into iron and the sulfur into 19 a very small quantity of hydrogen sulfide gas. The iron is both electrically highly conductive, and strongly magnetic.
21 This process step alters substantially all the pyrite 22 particles to a depth of at least one molecule to a new chemical 23 form characterized by enhancement of at least one of the pre-24 existing differences in magnetic susceptibility and electrical conductivity between the pyrite and the coal components of 26 the m xture. The process thereafter, in a third step, employs 27 one or both of these enhanced property differences to improve 28 separation of said components one from the other.
29 The step of pulverizing coal containing pyrite particles in the range 50 micrometers or smaller may fail to separate ~5/
;/1/7n9- ~144105 1 enough of the pyrite component from the coal component to 2 alLow subsequent steps of the process to achieve the required 3 sulfur-content reduction. In such cases pulverizing the 4 coal to even smaller sizes than minus 200 mesh may, instead, bring about`increased difficulties in handling the smaller-6 mesh powders that will be produced. I have found that certain 7 chemicals may be used to weaken the bond between the smaller-8 size pyrite particles and the coal matrix prior to the 9 crushing or pulverizing step, after which the effect of the pulverizing step is increased so that pyrite particles as 11 small as 37 micrometers can be physically separated from the 12 coal matrix. For example, if a sample of coal of this type 13 is wetted in an aqueous solution of ammonia or potassium 14 hydroxide for a few hours at atmospheric pressure and ambient temperature, and then dried, the step of pulverizing this 16 sample to minus 200 mesh will achieve increased physical 17 separation of the pyrite component from the coal component.
18 In a preferred process, the final step is performed in 19 a high tension separator, using a process heretofore generally called "electrostatic separation". The term "electrostatic 21 separation" as used in this specification is intended to have 22 the scope of meaning thatis ascribed to it in "Chemical 23 Engineers' Handbook", Robert H. Perry and Cecil H. Chilton, 24 Editorial Directors; 5th Edition 1973, in the article entitled "Electrostatic Separation" at pages 21-62 to 21-65 -- McGraw-26 Hill Book Company, l~ew York, N.Y.
~5/
i2/79 1~441~5 1 DETAILED ~ESCRIPTION OF THE INVENTION
2 The invention is further described with reference to 3 the accompanying drawings, in which:
4 FIG. 1 is a block diagram generally illustrating the invention; `
6 FIG. 2 illustrates the preliminary step of chemically 7 weakening bonds between pyrite and coal components; and 8 FIG. 3 illustrates a silent discharge device for 9 deagglomerating the pulverized mixture of pyrite and coal.
Figure 1 illustrates in a general way the process of the 11 invention. As illustrated, the process comprises three steps, 12 each of which is susceptible of being performed in a variety 13 of ways.
14 In Step 1 the coal is pulverized to -200 mesh. It is now known that pyrite is the major source of sulfur in ~oals, 16 and that pyrite can be distributed in coals on a scale finer 17 than 50 micrometers (~m). In order to separate the particles 18 of pyrite physically from the coal matrix in which they are 19 bound, the coal must be pulverized to -200 mesh or finer.
However, coal that is pulverized so fine is difficult to 21 handle. In a gaseous medium, such as air, the motions of 22 the very small particles of both coal and pyrite, many of 23 which have essentially the same effective aerodynamic diameters, 24 are governed essentially by Stokes' Law defining resistance to 25 motion, 26 R= 6~nav 27 where "n" is the fluid viscosity, "a" is the radius of the 28 particle (sphere), and "v" is the velocity of the particle.
29 Mass is not relevant at the small particle sizes that are present, with the result that th~ particles of both coal and ~45/
~I/2R/7r9 ~ 1~44~0S
1 pyrite are easily carried or scattered together throughout 2 an ambient gaseous environment and, conversely, one is not 3 separable from the other by the force of gravity alone.
4 Once the coal and pyrite are pulverized to the size range required to free a substantial percentage (i.e.: the 6 majority) all of the pyrite physically from the coal, these 7 two components can be differentiated in many ways, so as to 8 enable one component to be separated from the other in 9 subsequent process steps. More particularly, the next step in the process, Step 2, involves the conversion of pyrite ll into a form capable of either magnetic or electrostatic 12 separation from the coal. As it concerns the former, magnetic 13 separation, pyrite, an essentially non-magnetic substance, can14 be converted into a magnetic material by thermal means (some of which are known), or by chemical means. As it concerns the 16 latter, pyrite is relatively more conductive, electrically, 17 than is coal, and this difference can be enhanced by chemical 18 means, or by electrical means, or both acting together, so as 19 to render the pyrite functionally far more conductive, electrically, than is the coal, and thereby more easily capable 21 of separation from the coal by electrostatic means.
22 Magnetic separation of Pyrite from Coals is the subject 23 of a paper bearing that title by Sabri Ergun and Ernest H. Bean, 24 published by the Bureau of Mines (1968), United States Department of the Interior, Report of Investigations 7181. The 26 authors point out that some of the pyrite is converted into 27 ferromagnetic compounds of iron when heated to temperature 28 greater than 500C. Dielectric heating of coals in the Ghz 29 frequency range is suggested as the most feasible method of enhancing the paramagnetism of pyrite. Selective heating of R/~t ~4~
1 the pyrite was recognized in this report. However, the 2 heating times were such (up to 30 minutes in one example) 3 that the coal was also heated to a substantial degree, 4 requiring prohibitive total energy input. This is borne out in N.T.I.S. Report No. PB 285-880.
6 According to the present invention, the paramagnetism of 7 pyrite particles is more economically enhanced by chemically 8 or electrically transforming the surfaces of the pyrite 9 particles into compounds that are more magnetic than iron disulfide (pyrite). This is done chemically, for example, in 11 a treatment of pyrite and coal with halogen gases or the 12 vapors of their acids, such as hydrochloric, hydrobromic or 13 hydroiodic, so as to transform the pyrite particle surface into 14 ferrous or ferric chloride, bromide, or iodide. These compounds, in addition to being more magnetic than iron disulfide, are 16 less expensive to produce than pyrrhotite, the compound which is 17 produced by heating of the pyrite.
18 The surface chemistry of pyrite particles can be 19 electrically altered with an A.C. silent corona discharge.
Recombinations of ions on the surfaces of the particles will 21 result in high local temperatures ~as in corona nitriding of 22 steel) which, if carried out in the presence of an appropriate 23 gas or gasses, will in turn effect a desired chemical reaction.
24 A reactive gas may be introduced along with the pulverized coal and pyrite, between Step 1 and Step 2, as is indicated in 26 Figure 1.
27 In each of these examples, it is the surface of each 28 pyrite particle that is transformed into a compound or compounds 29 that are more magnetic than iron disulfide. It is necessary only to convert a shallow surface layer of each pyrite particle ~-~5/
:i~/jm_ ~2/79 1144i~5 1 to a more magnetic chemical, and this is an energy-saving 2 feature of the invention. It is presented also in the 3 following examples of steps for converting the pyrite into a 4 form that ismore capable of electrostatic separation from S coal.
6 Electrostatic separation of one type of particle from 7 another is possible even when the resistivities are as close as 8 within two or three orders of magnitude. This is sometimes the 9 difference between the electrical resistivities of pyrite versus coal, the pyrite being inherently more electrically 11 conductive than the coal. Electrodynamic separators 12 (employing charging by ion bombardment) are commercially 13 available which can separate particles having a ratio of 14 electrical conductivities approximately five or six orders of magnitude. It is necessary only to convert a shallow 16 surface layer of each pyrite particle to a highly conductive 17 chemical in order to render the pyrite particles functionally 18 far more conductive than are the coal particles; that is, to 19 enhance the pre-existing difference in the electrical conductivities of the two materials.
21 In theory, the enhanced-conductivity surface layer on 22 each pyrite particle need be only a molecule or so in depth.
23 This means that a reaction can take place nearly instantaneously, 24 and it is within the scope of this invention to effect such a reaction at any convenient time after the coal/pyrite mixture 26 leaves the pulverizer.
27 According to the invention, the electrical conductivity 28 of pyrite particles can be enhanced through electrical means 29 combined with chemical means, by passing the pyrite in the form of finely-divided particles, preferably carried in a reactant _g_ R~jn~
,'2/79 i~44~05 1 gas or vapor, between electrodes at least one of which is 2 insulated by a suitable dielectric, and applying between the 3 electrodes an A.C. voltage sufficiently high to cause a 4 silent corona discharge, and thereby create both positive and negative ions in the carrier gas (See Fig. 3). Recombinations 6 of ions on the surface of the pyrite particles result in high 7 local temperatures which if effected in the presence of a 8 reactant carrier gas or vapor will in turn promote or 9 accelerate desired reaction or reactions with such gas or vapor. The recombinations of ions will take place on the 11 surfaces of both the pyrite particles and the coal particles, 12 and intense local heating of these surfaces will result in 13 accelerated chemical reactions between the carrier gas and 14 one or both materials -- the pyrite and/or the coal. The carrier gas or vapor ought therefore to be chosen so as to 16 favor the desired reaction with the pyrite and to avoid or 17 minimize a reaction with the coal.
18 The surfaces of the pyrite particles can be converted 19 into an electrically more conductive compound by reacting the coal/pyrite mixture with chlorine gas, for example just after 21 the mixture leaves the pulverizer, so as to transform the 22 surface layer into ferrous and/or ferric chloride.
23 I have found in working with coal pulverized to minus 200 24 mesh that the coal particles tend to agglomerate, and form clumps. This tends to frustrate any following process step 26 which requires access to the surface of the particles (e.g.:
27 surface conductivity enhancement in the pyrite particles by 28 chemical means, or particle separation in apparatus which 29 depends upon charging the particles by ion bombardment). I
have found, further, that the particles of a -200 mesh mixture ~45/~ ~44~
IR/jnl_ 1 of coal and pyrite are de-agglomerated by passing the mixture 2 through an A.C. silent discharge following the pulverizing step 3 (Step 1). This step of de-agglomerating the particles of the 4 mixture provides access to the surfaces of substantially all the particles, and greatly increases the opportunity to enhance 6 the pre-existing electrical and/or magnetic difference between 7 pyrite and coal, and hence the opportunity to succeed in 8 separating the sulfur-bearing pyrite particles from coal particles.
9 Thus, Step 2 of the process of this invention simultaneously de-agglomerates the mixture of pyrite and coal particles and 11 more greatly enhances a pre-existing difference in their relative 12 electrical conductivity properties and/or their relative magnetic 13 susceptibility properties. Step 3 of the process, which can 14 be performed in any of a variety of known ways, is thereby rendered more effective, and improved.
16 Referring to Figure 2, the bond between pyrite particles 17 and coal matrix is weakened chemically in a preliminary step, 18 block 10, taken prior to Step 1 of the process as described 19 with reference to Figure 1. This preliminary step has been found effective to enhance the subsequent physical separation 21 of the pyrite component from the coal component of a bituminous 22 coal sample in which the pyrite exists in sizes down to about 23 50 micrometers. As an example, a quantity of coal containing 24 3.11% pyritic sulfur was treated with a chemical comminutant, in this example an aqueous solution of 29% ammonia at atmospheric 26 pressure and ambient temperature for a few hours, and then dried, 27 after which it was pulverized in a hammer mill to minus 200 mesh.
28 The pulverized sample was then treated with Step 2 and electro-29 statically separated in Step 3. The coal recovered after Step 3 had a sulfur content of 0.95%. The pyrite sulfur content was ~45/
/2/79 1~4410S
1 reduced 75~.
2 In Figure 3, a dielectric tube 20 (made, for example, 3 of "Pyrex" glass) has an electrically conductive first 4 electrode 21 on its outer surface, and an electrically S conductive second electrode 22 axially located within it.
6 The second electrode can be supported by any suitable holding 7 means (not shown) presenting the smallest possible impediment 8 to flow of the gas and particle mixture. Alternatively, the 9 tube 20 can have two outer electrodes on opposing outer surfaces, in which case the tube walls covered with the 11 electrodes should preferably be flat so that the electrodes 12 will be evenly spaced along the path through which the gas 13 (or vapor) and particle mixture flows. A pair of terminals 14 23, 24 are connected one to each electrode 21, 22, respectively, and an A.C. high voltage approximately 25,000 volts at a low 16 current approximately 1 milliampere is applied across these 17 terminals to produce a silent corona discharge between the 18 electrodes. The gas (or vapor) and particle mixture is passed 19 through this A.C. siient corona discharge, thereby to ionize the gas (or vapor) so as to promote a reaction between the gas 21 (or vapor) and at least the pyrite component in the coal and 22 pyrite mixture, with the results that are described above.
23 The effect of the A.C. silent corona discharge, whether 24 or not a reactant gas or vapor is present, is to deagglomerate the particles in the coal and pyrite mixture. When a mixture 26 pulverized to 200 mesh is passed through the tube 20 and 27 suitable A.C. voltage is applied at terminals 23, 24, the 28 particles execute rapid motion back and forth between the 29 electrodes 21, 22, and transverse to the direction of their passage between the electrodes, so much so that the interior o~4~_~.k ~4~//m~ ~441~
i2/79 1 of the tube becomes clouded with moving particles and blocks 2 substantially the light that would otherwise pass through the 3 tube. The output from the tube is a deagglomerated mixture 4 of coal and pyrite. When a reactant gas is also present, the pyrite h'as been altered to enhance its electrical and/or 6 magnetic properties, as is described above. This output is 7 supplied to separating means in Step 3.
Claims (9)
1. A process for reducing the sulfur content of coal comprising the steps of pulverizing the coal so as to free a substantial percentage of the pyrite component physically from the coal component, passing a mixture of said particles of the coal and the pyrite through an A.C. silent corona discharge so as to reduce adhesion by electrostatic forces and thereby de-agglomerate substantially all the particles, and thereafter separating said components one from the other.
2. A process according to claim 1 including, simultaneously with said de-agglomerating, altering the chemistry of the pyrite to enhance the difference in electrical conductivity between the pyrite component and the coal component, and thereafter electrostatically separating said components one from the other.
3. A process according to claim 1 including, simultaneously with said de-agglomerating, increasing selectively the magnetic susceptibility of the pyrite component relative to the coal component, and thereafter magnetically separating said components one from the other.
4. A process according to claim 1 including, simultaneously with said de-agglomerating, altering the surface of substantially all the pyrite particles to a depth of at least one molecule to a new chemical form having at least one of its magnetic susceptibility and its electrical conductivity substantially enhanced relative to the coal component, and thereafter separating said components one from the other.
5. A process according to claim 4 wherein the electrical conductivity of the pyrite particles is enhanced, including the step of electrostatically separating said components.
6. A process according to claim 4 wherein the magnetic susceptibility of the pyrite particles is enhanced, including the step of magnetically separating said components.
7. A process according to claim 1 in which the coal is pulverized to at least minus 200 mesh particle size.
8. A process according to claim 1 including the preliminary step of treating the coal with a suitable chemical so as to weaken bonds between the coal matrix and pyrite particles, and thereafter pulverizing the coal to physically separate the pyrite component from the coal component.
9. A process according to claim 8 wherein the chemical is 29% ammonia in water, and the coal is wetted in that solution in and therafter the coal is pulverized.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/064,726 US4260394A (en) | 1979-08-08 | 1979-08-08 | Process for reducing the sulfur content of coal |
| US064,726 | 1979-08-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1144105A true CA1144105A (en) | 1983-04-05 |
Family
ID=22057899
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000357855A Expired CA1144105A (en) | 1979-08-08 | 1980-08-08 | Process for reducing the sulphur content of coal |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4260394A (en) |
| EP (1) | EP0033342B1 (en) |
| JP (1) | JPS56500967A (en) |
| BE (1) | BE884649A (en) |
| CA (1) | CA1144105A (en) |
| DE (1) | DE3069665D1 (en) |
| FR (1) | FR2463179A1 (en) |
| NL (1) | NL8020305A (en) |
| WO (1) | WO1981000416A1 (en) |
| ZA (1) | ZA804718B (en) |
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| US4743271A (en) * | 1983-02-17 | 1988-05-10 | Williams Technologies, Inc. | Process for producing a clean hydrocarbon fuel |
| US4695290A (en) * | 1983-07-26 | 1987-09-22 | Integrated Carbons Corporation | Integrated coal cleaning process with mixed acid regeneration |
| US4543104A (en) * | 1984-06-12 | 1985-09-24 | Brown Coal Corporation | Coal treatment method and product produced therefrom |
| WO1986001820A1 (en) * | 1984-09-18 | 1986-03-27 | Lambda Group, Inc. | Microbiological method for the removal of contaminants from coal |
| WO1986002663A1 (en) * | 1984-10-30 | 1986-05-09 | Brown Coal Corporation | Coal treatment method and product produced therefrom |
| US4753033A (en) * | 1985-03-24 | 1988-06-28 | Williams Technologies, Inc. | Process for producing a clean hydrocarbon fuel from high calcium coal |
| US4661118A (en) * | 1985-04-15 | 1987-04-28 | The United States Of America, As Represented By The Secretary Of The Interior | Method for oxidation of pyrite in coal to magnetite and low field magnetic separation thereof |
| US5702244A (en) * | 1994-06-15 | 1997-12-30 | Thermal Energy Systems, Incorporated | Apparatus and method for reducing particulate emissions from combustion processes |
| US6467630B1 (en) * | 1999-09-03 | 2002-10-22 | The Cleveland Clinic Foundation | Continuous particle and molecule separation with an annular flow channel |
| US6467706B1 (en) * | 1999-11-29 | 2002-10-22 | Xerox Corporation | Method for recycling expanded polymers |
| WO2003070862A1 (en) * | 2002-02-15 | 2003-08-28 | Hazen Research, Inc. | Dry dust control materials |
| US8177963B2 (en) * | 2007-12-20 | 2012-05-15 | Exxonmobil Research And Engineering Company | Partial electro-hydrogenation of sulfur containing feedstreams followed by sulfur removal |
| US20090159503A1 (en) * | 2007-12-20 | 2009-06-25 | Greaney Mark A | Electrochemical treatment of heavy oil streams followed by caustic extraction or thermal treatment |
| US8557101B2 (en) | 2007-12-20 | 2013-10-15 | Exxonmobil Research And Engineering Company | Electrochemical treatment of heavy oil streams followed by caustic extraction |
| US8075762B2 (en) * | 2007-12-20 | 2011-12-13 | Exxonmobil Reseach And Engineering Company | Electrodesulfurization of heavy oils |
| US7985332B2 (en) * | 2007-12-20 | 2011-07-26 | Exxonmobil Research And Engineering Company | Electrodesulfurization of heavy oils using a divided electrochemical cell |
| US8486251B2 (en) * | 2008-08-05 | 2013-07-16 | Exxonmobil Research And Engineering Company | Process for regenerating alkali metal hydroxides by electrochemical means |
| MX341339B (en) | 2008-10-31 | 2016-08-17 | Cytec Tech Corp * | Process for enhancing electrostatic separation in the beneficiation of ores. |
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| US20110078948A1 (en) * | 2009-10-01 | 2011-04-07 | Chandrashekhar Ganpatrao Sonwane | Ash removal from coal: process to avoid large quantities of hydrogen fluoride on-site |
| KR20120129907A (en) * | 2010-01-13 | 2012-11-28 | 클리어사인 컨버스천 코포레이션 | Method and apparatus for elecrical control of heat transfer |
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| CN104136850B (en) | 2011-12-30 | 2016-09-28 | 克利尔赛恩燃烧公司 | For the method and apparatus strengthening Fire Radiation |
| US9377195B2 (en) | 2012-03-01 | 2016-06-28 | Clearsign Combustion Corporation | Inertial electrode and system configured for electrodynamic interaction with a voltage-biased flame |
| US9879858B2 (en) | 2012-03-01 | 2018-01-30 | Clearsign Combustion Corporation | Inertial electrode and system configured for electrodynamic interaction with a flame |
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| US9289780B2 (en) | 2012-03-27 | 2016-03-22 | Clearsign Combustion Corporation | Electrically-driven particulate agglomeration in a combustion system |
| CN104334970A (en) | 2012-05-31 | 2015-02-04 | 克利尔赛恩燃烧公司 | Burner with flame position electrode array |
| US9702550B2 (en) | 2012-07-24 | 2017-07-11 | Clearsign Combustion Corporation | Electrically stabilized burner |
| US9310077B2 (en) | 2012-07-31 | 2016-04-12 | Clearsign Combustion Corporation | Acoustic control of an electrodynamic combustion system |
| US8911699B2 (en) | 2012-08-14 | 2014-12-16 | Clearsign Combustion Corporation | Charge-induced selective reduction of nitrogen |
| US9513006B2 (en) | 2012-11-27 | 2016-12-06 | Clearsign Combustion Corporation | Electrodynamic burner with a flame ionizer |
| US9746180B2 (en) | 2012-11-27 | 2017-08-29 | Clearsign Combustion Corporation | Multijet burner with charge interaction |
| WO2014085696A1 (en) | 2012-11-27 | 2014-06-05 | Clearsign Combustion Corporation | Precombustion ionization |
| US9562681B2 (en) | 2012-12-11 | 2017-02-07 | Clearsign Combustion Corporation | Burner having a cast dielectric electrode holder |
| US20140170576A1 (en) * | 2012-12-12 | 2014-06-19 | Clearsign Combustion Corporation | Contained flame flare stack |
| US20140170575A1 (en) * | 2012-12-14 | 2014-06-19 | Clearsign Combustion Corporation | Ionizer for a combustion system, including foam electrode structure |
| US9441834B2 (en) | 2012-12-28 | 2016-09-13 | Clearsign Combustion Corporation | Wirelessly powered electrodynamic combustion control system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US614927A (en) * | 1898-11-29 | Process of and apparatus for separating metals and by-products from ores by electricity | ||
| US502431A (en) * | 1893-08-01 | Process of desulphurizing metallic ores | ||
| US1366457A (en) * | 1919-05-20 | 1921-01-25 | Aluminum Co Of America | Apparatus for calcining carbon for electrodes |
| US1731473A (en) * | 1923-04-21 | 1929-10-15 | John J Naugle | Method of treating carbonaceous material in an electric furnace or the like |
| GB819588A (en) * | 1956-08-02 | 1959-09-09 | Aluminium Lab Ltd | Improvements in or relating to the production of purified carbonaceous material |
| GB851502A (en) * | 1958-01-15 | 1960-10-19 | Kloeckner Huettenwerk Haspe A | Improvements in or relating to methods and apparatus for caking fine and super-fine ores |
| GB854729A (en) * | 1958-07-15 | 1960-11-23 | Klockner Huttenwerk Haspe Ag | Sintering of fine ores |
| FR1579577A (en) * | 1967-05-19 | 1969-08-29 | ||
| US4081251A (en) * | 1976-07-06 | 1978-03-28 | The United States Of America As Represented By The Secretary Of The Navy | Process to remove iron sulfide from coal to reduce pollution |
| US4052170A (en) * | 1976-07-09 | 1977-10-04 | Mobil Oil Corporation | Magnetic desulfurization of airborne pulverized coal |
| US4155715A (en) * | 1977-09-06 | 1979-05-22 | Occidental Petroleum Corporation | Process for reducing the organic sulfur content of char |
| DE2754468A1 (en) * | 1977-12-07 | 1979-06-13 | Kloeckner Humboldt Deutz Ag | PROCESS FOR DESULFURIZATION OF COAL, PREFERABLY POWER COAL |
| US4152120A (en) * | 1978-02-06 | 1979-05-01 | General Electric Company | Coal desulfurization using alkali metal or alkaline earth compounds and electromagnetic irradiation |
| US4169710A (en) * | 1978-03-29 | 1979-10-02 | Chevron Research Company | Process for comminuting and reducing the sulfur and ash content of coal |
-
1979
- 1979-08-08 US US06/064,726 patent/US4260394A/en not_active Expired - Lifetime
-
1980
- 1980-08-01 WO PCT/US1980/000976 patent/WO1981000416A1/en active IP Right Grant
- 1980-08-01 DE DE8080901683T patent/DE3069665D1/en not_active Expired
- 1980-08-01 NL NL8020305A patent/NL8020305A/en not_active Application Discontinuation
- 1980-08-01 JP JP50194180A patent/JPS56500967A/ja active Pending
- 1980-08-04 ZA ZA00804718A patent/ZA804718B/en unknown
- 1980-08-06 BE BE0/201663A patent/BE884649A/en not_active IP Right Cessation
- 1980-08-08 FR FR8017611A patent/FR2463179A1/en active Granted
- 1980-08-08 CA CA000357855A patent/CA1144105A/en not_active Expired
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1981
- 1981-02-24 EP EP80901683A patent/EP0033342B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0033342A4 (en) | 1982-01-08 |
| DE3069665D1 (en) | 1985-01-03 |
| WO1981000416A1 (en) | 1981-02-19 |
| EP0033342A1 (en) | 1981-08-12 |
| EP0033342B1 (en) | 1984-11-21 |
| US4260394A (en) | 1981-04-07 |
| JPS56500967A (en) | 1981-07-16 |
| FR2463179B1 (en) | 1984-03-16 |
| FR2463179A1 (en) | 1981-02-20 |
| NL8020305A (en) | 1981-07-01 |
| BE884649A (en) | 1980-12-01 |
| ZA804718B (en) | 1981-09-30 |
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