GB2181448A - Improvements in coal cleaning - Google Patents
Improvements in coal cleaning Download PDFInfo
- Publication number
- GB2181448A GB2181448A GB08608321A GB8608321A GB2181448A GB 2181448 A GB2181448 A GB 2181448A GB 08608321 A GB08608321 A GB 08608321A GB 8608321 A GB8608321 A GB 8608321A GB 2181448 A GB2181448 A GB 2181448A
- Authority
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- United Kingdom
- Prior art keywords
- coal
- liquor
- microbiological
- pyrites
- protein
- 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.)
- Granted
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- 239000003245 coal Substances 0.000 title claims abstract description 56
- 238000004140 cleaning Methods 0.000 title claims description 10
- 244000005700 microbiome Species 0.000 claims abstract description 25
- 108090000623 proteins and genes Proteins 0.000 claims abstract description 13
- 102000004169 proteins and genes Human genes 0.000 claims abstract description 13
- 230000002906 microbiologic effect Effects 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 claims description 42
- 238000009291 froth flotation Methods 0.000 claims description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 22
- 238000011282 treatment Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 229910052742 iron Inorganic materials 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 11
- 241000894006 Bacteria Species 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 7
- 239000008267 milk Substances 0.000 claims description 5
- 210000004080 milk Anatomy 0.000 claims description 5
- 235000013336 milk Nutrition 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 5
- 239000000725 suspension Substances 0.000 claims description 5
- 241000605222 Acidithiobacillus ferrooxidans Species 0.000 claims description 4
- 239000006185 dispersion Substances 0.000 claims description 4
- 239000000284 extract Substances 0.000 claims description 4
- 240000004808 Saccharomyces cerevisiae Species 0.000 claims description 3
- 235000014680 Saccharomyces cerevisiae Nutrition 0.000 claims description 3
- 238000000855 fermentation Methods 0.000 claims description 3
- 230000004151 fermentation Effects 0.000 claims description 3
- 241000605272 Acidithiobacillus thiooxidans Species 0.000 claims description 2
- 230000005660 hydrophilic surface Effects 0.000 claims description 2
- 239000012460 protein solution Substances 0.000 claims description 2
- 210000000170 cell membrane Anatomy 0.000 claims 1
- 150000002632 lipids Chemical class 0.000 claims 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 16
- 239000005864 Sulphur Substances 0.000 description 16
- 210000004027 cell Anatomy 0.000 description 12
- 239000000203 mixture Substances 0.000 description 9
- 230000003750 conditioning effect Effects 0.000 description 7
- 239000012153 distilled water Substances 0.000 description 7
- 239000012528 membrane Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000003153 chemical reaction reagent Substances 0.000 description 6
- 239000003039 volatile agent Substances 0.000 description 6
- 241000605118 Thiobacillus Species 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000001629 suppression Effects 0.000 description 4
- 230000001580 bacterial effect Effects 0.000 description 3
- 238000012258 culturing Methods 0.000 description 3
- 238000005188 flotation Methods 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 238000002386 leaching Methods 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 235000015097 nutrients Nutrition 0.000 description 3
- 241000588724 Escherichia coli Species 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000003250 coal slurry Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 210000003743 erythrocyte Anatomy 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- 230000007420 reactivation Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000013049 sediment Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- 239000001117 sulphuric acid Substances 0.000 description 2
- 241000228212 Aspergillus Species 0.000 description 1
- 241000228245 Aspergillus niger Species 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- 229910004861 K2 HPO4 Inorganic materials 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 241000589516 Pseudomonas Species 0.000 description 1
- 241000122973 Stenotrophomonas maltophilia Species 0.000 description 1
- FJWGYAHXMCUOOM-QHOUIDNNSA-N [(2s,3r,4s,5r,6r)-2-[(2r,3r,4s,5r,6s)-4,5-dinitrooxy-2-(nitrooxymethyl)-6-[(2r,3r,4s,5r,6s)-4,5,6-trinitrooxy-2-(nitrooxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-3,5-dinitrooxy-6-(nitrooxymethyl)oxan-4-yl] nitrate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O)O[C@H]1[C@@H]([C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@@H](CO[N+]([O-])=O)O1)O[N+]([O-])=O)CO[N+](=O)[O-])[C@@H]1[C@@H](CO[N+]([O-])=O)O[C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O FJWGYAHXMCUOOM-QHOUIDNNSA-N 0.000 description 1
- SOYDOYJQANMIEY-UHFFFAOYSA-N [As].[Ag]=S Chemical compound [As].[Ag]=S SOYDOYJQANMIEY-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 238000003321 atomic absorption spectrophotometry Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 210000000601 blood cell Anatomy 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 230000009089 cytolysis Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000003306 harvesting Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000005661 hydrophobic surface Effects 0.000 description 1
- 238000013101 initial test Methods 0.000 description 1
- 238000011081 inoculation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000002503 metabolic effect Effects 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001717 pathogenic effect Effects 0.000 description 1
- 150000003904 phospholipids Chemical class 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 210000005253 yeast cell Anatomy 0.000 description 1
Classifications
-
- 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
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D1/00—Flotation
- B03D1/001—Flotation agents
- B03D1/004—Organic compounds
-
- 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
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/005—General arrangement of separating plant, e.g. flow sheets specially adapted for coal
-
- 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
-
- 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
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D2203/00—Specified materials treated by the flotation agents; Specified applications
- B03D2203/02—Ores
- B03D2203/04—Non-sulfide ores
- B03D2203/08—Coal ores, fly ash or soot
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Physical Water Treatments (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
Abstract
Fine coal is treated using a microbiological liquor containing or derived from a microorganisms or a liquor containing protein, for a length of time, e.g. 0.1-5 minutes, sufficient to alter the surface. The treated fine coal is suitably froth floated, and the coal recovered has a reduced pyrites content. <IMAGE>
Description
SPECIFICATION
Improvements in coal cleaning
This invention concerns improvements in coal cleaning, more especially it concerns the reduction of pyritic sulphur in fine coal. Modern coal mining and processing methods produce a considerable amount of fine coal, which may be considered as coal of less than 0.5 mm., and an especially favoured method of recovery of coal from suspension, while at the same time reducing dirt content to some extent, is froth flotation. The principles, equipment and methods involved are well known to the coal preparation engineer. It is usual to add a froth flotation reagent to the coal slurry in order to form a stable bubble which will form the froth and also to assist the coal particles to attach to the bubbles and be carried upwards for recovery, while wetting the dirt particles so that they sink and are removed in tailings.
Considerable interest is currently directed to the sulphur contaminents of coal, since the sulphurous oxidation products from power stations have been put forward as a contributor to "acid rain" or other environmental problems. Inorganic sulphur in coal may be regarded as being almost solely iron pyrites, present in very small particles; unfortunately, these have similar hydrophobic surface properties to coal and tend to be concentrated in the recovered coal product of froth flotation. It is known that certain microorganisms, including especially Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans, are effective in leaching more than 80% of pyrites in coal and other minerals, but the leaching process takes several days since it involves culturing the bacteria and often has to be carried out under very acid conditions of the order of pH 1-2.In a case of a high volume mineral like coal, processing times and conditions of this order are not acceptable.
The present invention provides a coal cleaning process effective to reduce inorganic sulphur in coal which requires only minor changes in existing plant and methods, and offers substantial economic advantages compared with other methods of sulphur reduction before or after combustion.
The present invention provides a method of coal treatment comprising the contacting of fine coal with liquor selected from a microbiological liquor or an extract therefrom, and protein solutions or dispersions for a length of time sufficient to alter the surface properties of particles of iron pyrites such that they possess a substantially hydrophilic surface.
The invention as defined above may be considered as a "conditioning" process, and offers particular advantages when combined with conventional froth flotation. Accordingly, the invention further provides a coal cleaning method comprising a coal treatment step as defined above and the froth flotation of the treated fine coal in a subsequent or simultaneous step, whereby the coal recovered from the froth is of reduced pyrites content.
It has been found that the coal treatment method requires a contacting time of a few minutes or less; some laboratory experimental results show a beneficial effect in less than 10 seconds, and it is expected that commercial scale processes would operate on a contact time 0.1 to 5 minutes if the invention is operated as a two step froth flotation process.
The microbiological liquor may be a filtered microorganism culture liquor, a direct culture liquor containing the microorganism, a suspension of microorganisms, for example a suspension in water of a microorganism concentrate from a culture liquor or an aqueous suspension of lyophillised or lysed microorganisms or a filtered microorganism culture liquor supplemented with a microorganism concentrate or with lysed or lyophillised microorganisms. It is considered probable that the microorganisms may produce one (or more) metabolic products which is the active component in the surface property alteration of the iron pyrites, and the invention therefore includes an extracted form of any such active component from a culture liquor as well as synthetic forms thereof.Phospholipids or extracellular enzymes may be such active components, and although no active component has yet been identified, it appears probable that protein is the most likely active component.
Suitable microorganisms are the aforementioned Thiobacillus but other bacteria, fungi, lichens, yeasts etc. may be considered and tried. Effective pyrites suppression has also been found with strains of E.coli, Pseudomonas maltophila, Aspergillus niger and Saccaromyces cerevisiae, all of which are significantly more easy to culture than Thiobacillus. However, E. coli, Pseudomonas and Aspergillus are hazardous to health and hence Saccaromyces is preferred. In general, single strains of the microorganism are not believed to be essential to effective working of the invention, and mutants, whether natural or induced by known methods, may be used alone or together with strains found in nature. Thiobacillus bacteria have never been reported to be pathogenic, but conventional regular screening is advisable.Saccaromyces has been studied in detail by other researchers and is believed to be free of any significant hazard. Suitable culture liquors for use as liquors or as starting materials for liquors for the present invention may be cultured in known manner by inoculating an aqueous liquor containing sufficient nutrients, a nutrient salt solution, e.g. the "9K" solution (Journal of Bacteriology, 1959, 77, 642-647), with cells of the microorganism. The coal products may contain cells suitable for culturing without inoculation, and may also contain sufficient nutrients.In the production of Thiobacillus ferrooxidans, for example, the bacteria may be cultured in the "9K" solution supplemented with iron pyrites at an initial pH of up to 4.0, suitably 2.0 and temperature of 4 to 40"C, suitably 35"C under air agitation sufficient to gently mix and provide aerobic conditions. The bacteria may be harvested during or after the exponential growth cycle, during which time the pH will have fallen to about 1, as a result of sulphuric acid production.
Saccaromyces may be cultured in known manner, and preferably the yeast cells are lysed in known manner before, use of the resulting liquor.
We have also found that protein released by the lysis of red blood cells are effective to suppress pyrites during froth flotation.
We have further found that protein from other sources are effective. Such protein may be natural or synthetic. A particularly economic source of protein is milk; tests have shown that dilute milk also demonstrates pyrites suppression.
Although culturing of Thiobacillus, and known coal leaching processes, depend upon a low pH, tests show that the application of the method of the invention is largely unaffected by pH in the range 1 to 11. Conventional froth flotation liquors have pH values in the range 4.5 to 7.5, according to the coal being treated and, therefore, the method of the invention may be easily applied to and incorporated into a froth flotation plant. Additionally, operating temperature is not critical and the method operates satisfactorily in the temperature range 0 to 40"C.
Since the method of the invention relies upon surface effects, the surface area of the fine coal, which increases with decreasing particle size, and the concentration of the microorganisms or the concentration of active species; all these and other parameters should be considered and routine testing carried out to optimise liquor concentrations for a given fine coal feed.
The fine coal after treatment according to the invention is an especially favoured starting material for conventional froth flotation, using standard froth flotation cells and standard commercial phenolic or non-phenolic reagents. Over all particle sizes tested, the method of the invention resulted in decreased sulphur in floated product and increased sulphur in tailings. In a commercial froth flotation plant, raw feed coal is mixed with recycled water and metered quantities of reagents in a tank with a nominal residence time of about 2 minutes (this is generally termed "conditioning") before being passed into a battery of cells, where the mixture is agitated by an impellor and streams of bubbles passed through. The stable froth passes over a weir and is dried, for example on a vacuum drum filter.It is usual for the process water recovered from the filter and from the tailings treatment, to be recycled. In the process of the present invention, the recycled process water will contain microorganisms or active components and the raw fine coal feed may be treated in a first tank with recycled water and fresh liquor or solids from a local fermentation reactor (if microorganism-derived liquor is used) or a tank containing lysed cells or a source of protein, before being passed to the conditioning tank. Since a well-operated froth flotation plant recycles about 98% by weight of the water in the circuit, a local fermentation reactor need only be quite small.Alternatively, of course, previously produced solutions or dispersions or dispersions of microorganisms or lyophillised or lysed microorganisms, extracts etc. or natural protein sources may be dosed into the process water in the microbiological conditioning tank or the first cell of the froth flotation bank.
It will be realised that the invention will increase the quantity of iron pyrites in the tailings from froth flotation plants. The iron pyrites may be recovered from the tailings, if desired, by a reactivation step, which is effective to counteract the suppression of the surface properties of the pyrites. This may be done in a number of ways, including conditioning resuspended tailings (optionally after drying) using a standard commercial froth flotation reagent, before froth floating the pyrites. An additional treatment/conditioning step using dilute copper sulphate solution, together with reagent is also effective, and tests have shown that 75-85% by weight of the pyrites content of the tailings may be recovered by reactivation and froth flotation. The recovered iron pyrites may be a useful indigenous source of sulphur and/or sulphuric acid for industry, using known technology.
The invention will now be described by way of example only.
EXAMPLE 1
Bacterial Culture
A sample of Thiobacillus ferrooxidans in distilled water at pH 2.0 was innoculated at a density of 1x109 cells/ml. per 1% pulp density into a "9K" mineral salts medium consisting of 3.0 g (NH4)2504, 0.1 g KCI, 0.5 g K2 HPO4 and 0.01 Ca (NO3)2 in 1 litre distilled water, adjusted to pH 2.0 and supplemented with-53 micron iron pyrites to obtain a 6% pulp density. The culture was grown in a laboratory aerated fermenter at 35"C, and growth was monitored by assaying iron release into the bacterial liquor by atomic absorption spectrophotometry. Towards the end of the exponential phase of growth, samples of the liquor were taken.Some of the samples were centrifuged in order to harvest the bacteria, which were resuspended and washed twice with distilled water acidified to pH 2.0. Some samples were filtered through a cellulose nitrate membrane of 0.45 ,am pore size. Bacterial counts were established using a UV/Vis spectrophotometer.
Treatment Step
Initial tests were carried out on washed iron pyrites. Samples of212+106 micron pyrites were subjected to various pre-treatments and suspended in pH 2.0 distilled water. A laboratory
Hallimond tube flotation apparatus was used to determine what percentage of the pyrites were floated, and the results are given in Fig. 1. The best suppression of the flotation properties of pyrites was given by a membrane filtered liquor supplemented by bacteria to a density of 1.0 x 1010 cells/ml.
A coal/pyrites mix was prepared by using a coal from the Nottinghamshire High Hazles seam, at a weight ratio of 4.8:1. An analysis of each component is given in Table 1.
Table 1
Material Sulphur Arsenic Silver Ash Volatiles Moisture Fixed
Content Carbon
Pyrites 47.4 0.24 1.0 - - 0.26 Coal 0.9 2 3 2.3 36.0 9.10 52.7 The mixture was treated for two minutes with the supplemented membrane filtered liquor mentioned above, at a pH of 2.0. The treated mixture was admixed with a commercial reagent at a dosage of 60 mg/l and a conditioning time of 2 mins, transferred to a laboratory froth flotation cell at a 2% pulp density and frothed for 3 minutes. The froth was recovered, filtered and dried and the tailings product treated similarly. The effect of the treatment according to the invention is compared with no such treatment, in Table 2 below.
Table 2
FROTH (% by wt). ZitTAILINGS (% by wt) treated control treated control Dry Yield 70.4 92.7 29.6 7.3 Air dried Sulphur 2.1 10.9 1 30.9 36.9 Ash 3.1 10.3 42.5 54.1 Fixed Carbon 54.7 52.6 t 26.2 1 * I Volatiles | 39.2 35.4 35.4 31.1 *insufficient sample.
Tests have also been conducted in a mechanically stirred froth flotation cell and similar results have been obtained. It is seen that the treatment according to the invention depresses the froth yield, because of an increase in tailings produced. There is a substantial decrease in the sulphur content of the coal recovered from the froth, and the treated product coal is clearly a higher value product (reduced sulphur, reduced ash, increased volatiles and fixed carbon) than the product coal without treatment. This also offers the possibility of increasing the value of other coal by blending. Alternatively, in certain situations, all the coal may be treated according to the invention; this may be particularly suitable for coal slurry combustion, e.g. in power stations.
EXAMPLE 2 1 ml red blood cells were lysed by resuspension in 3ml distilled water and were centrifuged to sediment the membrane components (which contain approximately 2096 protein, by wt). The membrane sediment was then resuspended in 4.0ml distilled water. 100 ,ul of the suspension was added to 300ml of water containing suspended -212+106 ,um pyrites in a laboratory
Hallimond tube flotation apparatus. The blood cell membrane treatment yielded a froth containing 12.25% by weight of the pyrites. A control test without the treatment according to the invention yielded a froth containing 89.7% by weight of the pyrites.
EXAMPLE 3
A synthetic coal/pyrites mix was prepared as described in Example 1, containing 7.4% by weight of sulphur. The mix was froth floated in a laboratory froth flotation cell using the procedure described in Example 1, but using, instead of the supplemented membrane filtered liquor, 200, l of a liquor prepared from commercial milk diluted with 9 times its volume of distilled water. The results of froth flotation tests are given in Table 3 below.
TABLE 3
FROTH (X by wt). I TAILINGS (% by wt) treated control treated control Dry Dry Yield 91.0 95.64 8.96 4.36 Sulphur (air dried wt) 1.25 6.35 Not analysed Not analysed Ash (dry wt) 2.21 6.89 Fixed Carbon (") 58.18 55.80 Volatiles (") 38.56 37.3 It can be seen that the invention gives a significant reductions in sulphur and ash and an increase in fixed carbon and volatiles in the product recovered from the froth.That is, a higher value product is obtained and the reduction in yield is accounted for by the loss to tailings of pyrites.
EXAMPLE 4
A synthetic coal/pyrites mix was prepared as described in Example 1, containing 10.7% sulphur by wt. The mix was froth floated in a laboratory froth floation cell using the procedure described in Example 3, but using 300 pl of the dilute milk. The results are shown in Table 4 below.
TABLE 4
FROTH (% b wt). I TAILINGS (% by wt) treated control treated control Dry Dry Yield 79.7 95.4 20.3 4. 6 Sulphur (air dried wt) 1 1.84 8.15 * 48.0 Ash (dry wt) 2.25 10.73 * 67.1 Fixed Carbon (") 59.2 53.11 * 0.15 Volatiles (") 38.7 36.16 * 32.7 * No analysis performed
Significant improvements over the control are shown, as in Example 3.
Claims (16)
1. A method of coal treatment comprising the contacting of fine coal with a liquor selected from a microbiological liquor or an extract therefrom, and protein solutions or dispersions for a length of time sufficient to alter the surface properties of particles of iron pyrites such that they possess a substantially hydrophilic surface.
2. A method according to claim 1, wherein the contact time is from 0.1 to 5 minutes.
3. A method according to claim 1 or 2, wherein the microbiological liquor is selected from filtered microorganism culture liquors, direct culture liquors containing the microorganisms, and microorganism supplemented filtered liquors or direct culture liquors.
4. A method according to claim 1 or 2, wherein the microbiological liquor is an extract of a culture liquor.
5. A method according to any one of the preceding claims, wherein the microbiological liquor contains lysed microorganisms or a protein extracted therefrom.
6. A method according to any one of the preceding claims, wherein the microorganism is
Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans or Saccaromyces cerevisiae.
7. A method according to any one of the preceding claims, wherein the liquor comprises bacteria harvested during or after the exponential growth cycle.
8. A method according to Claim 1 or 2, wherein the treatment liquor is a solution or suspension of a natural or synthetic protein.
9. A method according to Claim 8, wherein the natural lipid is derived from lysed cell membranes.
10. A method according to claim 8, wherein the natural protein is or is derived from milk.
11. A method according to claim 1, substantially as hereinbefore described.
12. A coal cleaning method comprising a coal treatment step, according to any one of the preceding claims, and the froth flotation of the treated fine coal in a subsequent or simultaneous step, whereby the coal recovered from the froth is of reduced pyrites content.
13. A coal cleaning method according to claim 12, wherein the first step utilises recycled process water from the froth flotation step, made-up using a source of microbiological liquor, a source of microorganisms or a source of protein.
14. A coal cleaning method according to claim 9, wherein the make-up microbiological liquor is derived from an adjacent fermentation vessel.
15. A coal cleaning method according to claim 13, substantially hereinbefore described.
16. A coal cleaning method according to any one of claims 13 to 15, further comprising the step of recovering pyrites from the tailings of the froth flotation plant.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858524746A GB8524746D0 (en) | 1985-10-08 | 1985-10-08 | Coal cleaning |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8608321D0 GB8608321D0 (en) | 1986-05-08 |
| GB2181448A true GB2181448A (en) | 1987-04-23 |
| GB2181448B GB2181448B (en) | 1989-09-27 |
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Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858524746A Pending GB8524746D0 (en) | 1985-10-08 | 1985-10-08 | Coal cleaning |
| GB8608321A Expired GB2181448B (en) | 1985-10-08 | 1986-04-04 | Improvements in coal cleaning |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858524746A Pending GB8524746D0 (en) | 1985-10-08 | 1985-10-08 | Coal cleaning |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU581786B2 (en) |
| DE (1) | DE3632980A1 (en) |
| GB (2) | GB8524746D0 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109604046A (en) * | 2018-11-20 | 2019-04-12 | 朱计平 | A kind of coal preparation method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4206288A (en) * | 1978-05-05 | 1980-06-03 | Union Carbide Corporation | Microbial desulfurization of coal |
-
1985
- 1985-10-08 GB GB858524746A patent/GB8524746D0/en active Pending
-
1986
- 1986-04-04 GB GB8608321A patent/GB2181448B/en not_active Expired
- 1986-09-23 AU AU63045/86A patent/AU581786B2/en not_active Expired - Fee Related
- 1986-09-29 DE DE19863632980 patent/DE3632980A1/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4206288A (en) * | 1978-05-05 | 1980-06-03 | Union Carbide Corporation | Microbial desulfurization of coal |
Also Published As
| Publication number | Publication date |
|---|---|
| AU581786B2 (en) | 1989-03-02 |
| DE3632980A1 (en) | 1987-04-09 |
| GB8608321D0 (en) | 1986-05-08 |
| GB8524746D0 (en) | 1985-11-13 |
| GB2181448B (en) | 1989-09-27 |
| AU6304586A (en) | 1987-04-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |