GB2136015A - Collector for flotation of coal and other carbonaceous material - Google Patents

Abstract

The invention concerns a collector for the flotation of coal or carbonaceous materials comprising a halogenated hydrocarbon or a mixture of halogenated hydrocarbons the molecular mass or mean molecular mass (in the case of a mixture) being in excess of 150 so that at least some of the halogenated hydrocarbon does not evaporate under flotation conditions.

Description

SPECIFICATION Collector for flotation of coal and other carbonaceous material This invention relates to a collectorforflotation of coal and other carbonaceous material.

Generally, the reagents useful in beneficiation of coal by froth flotation comprise a frother, for example pine oil or 4-methyl 2-pentanol, and a hydrophobic oil as collector or conditioner, for example paraffin, kerosineorcreosote. Certain commercial products contain components providing both ofthesefunc- tions, for example crude cresylic acid or waste liquors from coke production.

Those materials known to be usefulas coal collectors comprise compounds of carbon and hydrogen, that is aliphatic and aromatic hydrocarbons generally containing 8 or more carbon atoms, and compounds of carbon, hydrogen and oxygen,such as alkylphenols and related products derived from pyrolysis of coal. The addition of detergents, for example esters of sulphosuccinic acid to hydrocarbon collectors is known, but the purposeofthis isto improve the dispersion of the hydro-carbon in the coal suspension ratherthan contribute directlyto the collector properties ofthe hydrocarbon.

A process related to coal flotation is the recovery by flotation ofcarbonaceous material, in particular activated carbon, from an ore suspension or pulp in which the carbonaceous material contains a valuable metal such as gold or silver.

According to the present invention, a collectorfor coal or other carbonaceous material, comprises a halogenated hydrocarbon in a dispersible form and of sufficient molecular mass to preclude substantial loss by evaporation during the collecting step.

In the preferred form of the invention the halogenated hydrocarbon or hydrocarbons chosen are in the liquid state. However, those which exist as solids or viscous liquids may be applied as solutions in suitable solvents. Such solvents should be inert or may themselves have frothing for coal or other carbonaceous material collecting properties.

In one form ofthe invention an admixture of one or more halogenated hydrocarbons with liquid hydrocarbons is provided, and, in particular,those liquid hydrocarbons which are known to be useful in coal flotation.

In general the molecular mass ofthe halogenated hydrocarbons should exceed about 150, preferably lies in the range 170 to 105, and more particularly 200 to 2000.

The halogenated hydrocarbons are conveniently the chlorinated hydrocarbons, that is compounds of carbon, hydrogen and chlorine conveniently prepared by reaction of a chlorinating agent with aliphatic, cycloaliphatic or aromatic hydrocarbons.

The chlorine contentofthe product by mass may range from the higher of 5% or one chlorine atom per molecule to 85%, is preferably 10% to 75%, and more particularly 15% to 60%.

The invention is illustrated bythefollowing examples, in which the amounts of reagents used are stated on grams pertonneofdrycoal (g/t).

Example 1 A chlorinated paraffin manufactured by Klipfontein Organic Products Limited containing 48% m/m chlorine and of molecular mass about 370 (sold as P48LM PLASTICLOR) was mixed with 1/5 of its mass of acetone to form the collector mixture. Coal fines essentiallysmallerthan 0,5 mm, and containing 33% m/m ash were obtained from a coal plant treating an Eastern Transvaal coal. A pulp containing 10% by mass ofthesefines was made up in a Denver D-1 2 laboratory flotation machine, and treated with a 100 g/t proprietory frother and 350 g/t ofthe collector mixture. Coal was recovered by flotation for 2 minutes, and the mass recovery of dry coal determined to be 34,3%.

Example2 The same chlorinated paraffin used in Example 1 was mixed with twice its mass of commercial power paraffin, and the same test procedure used. Mass recovery of dry coal was 56,6%.

Example 3 Three different chlorinated paraffinswere each mixed with twice their mass of power paraffin as in Example 2, and compared by the same test proce dupe, except that the proprietory frother TEB manufactured by NCP (Natal) Limited was used at 200 g/t.

The dried concentrates and tailings were analysed for ash, and the recovery of combustible matter (DAF coal) calculated.

lean Concentrate Recovery PLASTICLO 9 Chlorine Mean Ilasa Ash 9 s/n DAF Coal 9 P4BLM 49 560 13.6 76 P52L 51 390 12.6 73 P40L 41 540 13.1 72 Example 4 The chlorinated paraffin tested in Example 3 containing 49% chlorine was mixed with power paraffin to form two collector mixtures, in the mass properties 50 : 50 and 20 : 89 respectively.These and the power paraffin used were compared using the method of Example 3, but at levels of 310, 390 and 470 g/t respectively.

Level Concentrate Recovery Mixture g/t Ash 9 m/m OAF Coal 9 50:50 310 13.6 73 20:80 390 14.2 75 0:100 470 13.2 70 The effectiveness of the combination of chlorinated hydrocarbon and paraffin is shown.

Example 5 The 50 50 mixture of Example 4was used as collector, and a frother mixture made of TEB and the collector mixture in mass proportion of 4:1. These reagents were tested using the method of Example 3 at 390 g/t and 180 g/t respectively. A concentrate containing 13.5% ash and representing a recovery of DAF coal of 75% was obtained. The effectiveness of the chlorinated hydrocarbon in combination with a frotheris shown.

Example 6 Asample oftailings from a plant treating a Western Transvaal gold ore was made into a pulp containing 25% by mass ofthetailingsand 0.12% by mass of an activated charcoal. This was treated with 180 g/t of the proprietoryfrother Senfroth 9000 manufactured by NCP (Natal) Ltd, and 150 git of the collector mixture of Example 4. Concentrate was removed for 2 minutes.

The recovery of charcoal was calculated from combustion of the dry concentrate to be 69% by mass.

Additional examples were carried out with a variety of halogenated hydrocarbons. In all oftheexamplesa sample of coal finer was obtained from the North Western Transvaal. Thiswas made into a pulp containing 131/2% solids and su bjected to flotation using as collector 300 glt of each example, and as frothed 40 glut of Senfroth TEB. Dry ash-free coal in products was determined using ASTM Method D271.

The results of the examples are embodied in the following table:

Collector Mass Conc. Tail Recovery Grade Grade Recovery Halogen Type Compound z % DAT t-DAF DAF z Fluorine Alkyl Fluorohexadecane 22,7 87,2 59,5 30,1 Aryl 3-Fluoroxylène 16,1 81,3 62,5 20,3 Chlorine Alkyl 1-Chlorodecane 44,7 83,4 52,6 56,2 dichiorononane 28,1 84,8 56,8 36,8 Aryl za-dichiorobensene 13,0 81,8 62,7 16,2 1,2,4-trichloro- benzene 16,8 83,5 61,0 21,6 1,3,5-trichloro- benzene 41,0 81,6 53,8 51,3 Bromine Alkyl 1-bromodecane 21,2 85,9 60,1 27,7 1,8-dibromodecane 44,7 83,4 52,6 56,2 1,2-dibromocyclo- hexane 16,0 83,0 60,8 20,6 Aralkyl ss-broxDisopropyl- benzene 26,0 81,8 56,5 33,7 Iodine Alkyl 1-iodohexane 34,1 82,4 54,5 43,8 Aryl o-iodotoluene 18,3 82,9 62,5 22,9 paraffin 44,8 83,7 50,0 57,7

Claims (6)

1. Acollectorforcoal or other carbonaceous material comprising one or more halogenated hydrocarbons in a dispersible form and having a molecular mass or mean molecular mass exceeding 150.

2. Acollectorforcoal or other carbonaceous material comprising a mixture of one or more halogenated hydrocarbons having a molecular mass above 150, with a liquid hydrocarbon known to be useful in coal flotation.

3. Acollectoraccording to claim 1 in which the halogen is chlorine and is presenttothe extent of between 5 and 85 percent per molecule.

4. Amethodofflotation ofcoal orothercarbo- naceous material including the step of adding to the material required to be treated, an amount of a collector according to any of claims 1 to 3.

5. A collector substantially as described in any of the examples.

6. A method offlotation substantially as described in any of the examples.