GB2197226A - The use of collector mixtures as aids in the flotation of non-sulfidic ores, more especially cassiterite - Google Patents

Abstract

In the froth flotation of non-sulfidic, e.g. tin, ores, use is made of a collector mixture containing (a) alkyl and/or alkenyl glycosides and (b) monoalkylstannoates, the ratio of (a) to (b) being adjusted to a value of from 4:1 to 1:4. The monoalkylstannoate have the general formula RSn(O)OMe in which Me is sodium, potassium or hydrogen and R is preferably a linear saturated alkyl radical containing 2 to 10 carbon atoms.

Description

SPECIFICATION The use of collector mixtures as aids in the flotation of non-sulfidic ores, more especially cassiterite This invention relates to the use of alkyl glycosides in combination with monoalkyltin compounds as flotation collectors for non-sulfidic ores, more especially cassiterite.

Flotation is a separation technique commonly used in the dressing of mineral raw materials for separating valuable minerals from the gangue minerals. Non-sulfidic minerals are, for example, apatite, fluorite, scheelite and other salt-containing minerals, cassiterite and other metal oxides, for example oxides of titanium and zirconium, and also certain silicates and alumosilicates. For flotation, the ore is subjected to preliminary size reduction, dry-ground, but preferably wetground and suspended in water. Collectors are normally added to the ores, frequently in conjunction with frothers and, optionally, other auxiliary reagents, such as regulators, depressors (deactivators) and/or activators, in order to facilitate separation of the valuable minerals from the gangue constituents of the ore in the subsequent flotation process.These reagents are normally allowed to act on the finely ground ore for a certain time (conditioning) before air is blown into the suspension (flotation) to produce a froth at its surface. The collector acts as a hydrophobicizing agent on the surface of the minerals, causing the minerals to adhere to the gas bubbles formed during the aeration step. The mineral constituents are selectively hydrophobicized so that the unwanted constituents of the ore do not adhere to the gas bubbles. The mineralcontaining froth is stripped off and further processed. The object of flotation is to recover the valuable mineral of the ores in as high a yield as possible whilst, at the same time, obtaining a high enrichment level.

It is known that cassiterite can be separated off from gangue minerals by flotation, for which purpose various collectors are used due to the type of ore. For ores containing gangue minerals which are not hydrophobicized by anionic collectors, such as for example unsaturated and saturated fatty acids, more especially tall oil fatty acids and oleic acids, alkyl sulfates or sulfonates, it is sufficient to use these materials as collectors. Tin ores which are more difficult to float require more selective collectors, such as for example phosphonic acids (DE-PS 2 443 460 and DD-PS 76 974) or alkyl sulfosuccinamates (US-PS 3 830 366).

Suitable organic phosphonates for the flotation of cassiterite are water-soluble salts of organic phosphonic acids, for example salts of styrene phosphonic acid, as described for example in Xth Int. Mineral proc. Congress IMM, E. Topfer, pp. 626-627, London 1973 (O.S. Bogdanow).

By virtue of their surfactant character, many collectors for tin ores themselves develop a froth suitable for flotation. However, it may also be necessary to develop or suitably to modify the froth by special frothers. Known flotation frothers are C4-C10 alcohols, polypropylene glycols, polyethylene glycols or polypropylene glycol ethers, terpene alcohols (pine oils) and cresylic acids. If necessary, modifying reagents, for example pH regulators, activators for the mineral to be recovered in the froth or deactivators for the unwanted minerals in the froth, and possibly even dispersants are added to the flotation suspensions (pulps).

In contrast to anionic and cationic surfactants, nonionic surfactants are hardly used as collectors in flotation. In Trans. Inst. Met. Min. Sect. C., 84 (1975), pp. 34-39, A. Doren, D. Vargas and J. Goldfarb report on flotation tests on quartz, cassiterite and chrysocolla which were carried out with an adduct of 9 to 10 moles ethylene oxide with octyl phenol as collector.

Combinations of ionic and nonionic surfactants are also occasionally described as collectors in the relevant literature. Thus, A. Doren, A. van Lierde and J.A. de Cuyper report in Dev. Min.

Proc. 2 (1979), pp. 86-109 on flotation tests carried out on cassiterite with a combination of an adduct of 9 to 10 moles ethylene oxide with octyl phenol and an octadecyl sulfosuccinate. In A.M. Gaudin Memorial Volume, edited by M.C. Fuerstenau, AIME, New York 1976, Vol. l, pp.

597-620, P.M. Lovell describes flotation tests carried out on apatite with a combination of tall oil fatty acid and nonylphenyl tetraglycol ether.

In German patent application P 35 36 975.2, it is proposed to use alkyl glycosides in addition to anionic, cationic or ampholytic surfactants as aids in the flotation of non-sulfidic ores.

Monoalkyltin compounds have been described in principle as flotation collectors for cassiterite (Int. Tin Research Council, Annual Report 1984, Greenford, England 1985).

In many cases, the anionic and ampholytic collectors used for the flotation of tin ores do not lead to satisfactory recovery of the valuable minerals when used in economically reasonable quantities. Accordingly, the object of the present invention is to make flotation processes more economical by the provision of improved collectors with which it is possible to obtain either greater yields of valuable mineralsfor the same quantities of collector or the same yields of valuable minerals for reduced quantities of collector.

It has been found that alkyl and/or alkenyl glycosides in conjunction with monoalkyltin compounds are very effective collector systems for the flotation of tin ores. It has surprisingly been found that, where the two types of reagent mentioned are combined, a distinct synergistic enhancement of effect is observed in the flotation of tin ores.

Accordingly, the present invention relates to the use of alkyl and/or alkenyl glycosides in combination with mono-alkyltin compounds as collectors in the flotation of non-sulfidic ores, more especially cassiterite.

The alkyl or alkenyl radicals of the glycosides used in accordance with the invention may be linear or branched, may contain from 2 to 18 carbon atoms and may optionally contain a hydroxyl group and/or instead of a -CH2-group an ether bridge. Alkyl and/or alkenyl monoglycosides and/or polyglycosides containing from 2 to 8 glycoside residues are suitable for use in accordance with the invention, alkyl and alkenyl glycosides containing from 1 to 3 glycoside residues being preferred.

The alkyl and alkenyl glycosides used in accordance with the invention are a known class of compounds and may be produced by conventional methods of organic synthesis. In this connection, reference is made to US patents 3 547 828, 3 707 535 and 3 839 318, to DE-OS nos. 1 905 523, 1 943 689, 2 036 472 and 3 001 064 and also to published European patent application 0 077 167 and to P 35 36 975.2.

So far as the saccharide residue of the alkyl glycosides is concerned, both alkyl and/or alkenyl monoglycosides in which a cyclic sugar residue is attached to the alcohol and corresponding oligomers containing from 2 to 8 glycosidebonded glucose or maltose residues are suitable.

Alkyl and alkenyl glycosides containing from 1 to 3 glycoside residues are preferably used. The number of sugar residues is a statistical mean value based on the distribution normally occurring in these products. Alkyl and/or alkenyl glycosides based on C12-C14 fatty alcohols and one to two glycoside residues may be particularly suitable.

The monoalkylstannoates used in accordance with the invention correspond to the following general formula RSn(O)OMe in which Me is sodium, potassium, hydrogen and R is a preferably linear saturated alkyl radical containing from 2 to 10 and preferably from 2 to 8 carbon atoms.

The sodium salts of monobutylstannoate are preferably used.

In the mixtures of alkyl glycosides (a) and monoalkyltin compounds (b) used in accordance with the invention, the ratio by weight of component (a) to component (b) is in the range form 4:1 to 1:4.

The quantities in which the collector mixtures employed in accordance with the invention are used are determined by the type of ores to be flotated and by their content of valuable mineral.

Accordingly, the particular quantities necessary may vary within wide limits. In general, the collector mixtures according to the invention are used in quantities of from 100 to 1500 g per metric tonne of crude ore.

In practice, the alkyl and/or alkenyl glycosides used in accordance with the invention in combination with monoalkyl tin compounds are used instead of the known collectors in the known flotation processes for tin ores. Accordingly, the particular reagents commonly used, such as frothers, regulators, activators, deactivators, etc. are again added to the aqueous suspensions of the ground ores in addition to the collector mixtures. Flotation is carried out under the same conditions as state-of-the-art processes.

In this connection, reference is made to the following literature on ore preparation technology: H. Schubert, Aufbereitung fester mineralischer Rohstoffe, Leipzig 1967; B. Wills, Mineral Processing Technology, New York 1978; D.B. Purchas (ed.), Solid/Liquid Separation Equipment Scale-up, Croydon 1977; E.S. Perry, C.J. van Oss, E. Grushka (ed.), Separation and Purification Methods, New York, 1973-1978.

The collector mixtures used in accordance with the invention may be used, for example, in the separation of cassiterite by flotation from quartz and silicates.

The present invention also relates to a process for the separation of cassiterite from tin ores by flotation, in which ground ore is mixed with water to form an ore suspension, air is introduced into the resulting suspension and the froth formed is stripped together with the mineral therein. This process is characterized in that alkyl and/or alkenyl glycosides in combination with monoalkyltin compounds are used as collectors.

The following Examples are intended to demonstrate the superiority of the collector mixtures used in accordance with the invention. The tests were carried out under laboratory conditions, in some cases with increased collector concentrations considerably higher than necessary in practice. Accordingly, the potential applications and in-use conditions are not limited to the separation exercises and test conditions described in the Examples. All percentages are percentages by weight, unless otherwise indicated. The quantities indicated for reagents are all based on active substance.

EXAMPLES COMPARISON EXAMPLE 1 The material to be floated was a South African cassiterite ore low in valuable minerals and essentially containing granite, tourmaline and magnetite as gangue. The flotation batch had the following particle size distribution: 49.5% < 25 llm 43.8% 25 - 63 llm 6.75k > 63 llm The flotation tests were carried out at room temperature in a 1 liter laboratory flotation cell.

Waterglass was used as depressor in a quantity of 2000 g/t. The pH value of the pulp was adjusted to pH 5 with sulfuric acid before addition of the collector. Flotation was carried out with a pulp density of 500 g ore per liter tapwater having a hardness of 160 Gh (German hardness). The flotation time of the rougher flotation was 4 minutes at a stirring speed of 1200 r.p.m.

Collector: Butylstannoate, prepared by addition of monobutyltin trichloride to sodium hydroxide (L.A.

Hobbs, Ph.D. Thesis, University College, London 1985), was used in the form of a 0.1 M aqueous solution. Since butyl stannoate on its own does not have a frothing effect, one drop of methyl isobutyl carbinol was added as frother.

COMPARISON EXAMPLE 2 Flotation conditions as in Comparison Example 1.

Collector: Alkylglycoside of propylene glycol glycoside reacted with a-dodecane epoxide. This alkyl glycoside generates sufficient froth in the flotation tests so that no frother has to be added.

EXAMPLE 1 Flotation conditions as in Comparison Example 1.

Collector: An alkyl glycoside of propylene glycol glycoside reacted with a-dodecane epoxide was used as co-collector (1). The results of the tests with butylstannoate alone and a 1:1 mixture of butylstannoate and alkyl glycoside and the alkyl glycoside alone are shown in Table 1. They show that the organotin compound used on its own produces an inadequate recovery for moderate selectivity. As can be seen from the flotation result, there is no enrichment of cassiterite in the flotation froth where the alkyl glycoside is used on its own. By contrast, where the collector mixture is used, a higher recovery level is obtained in conjunction with high enrichment of tinstone in the rougher concentrate.

COMPARISON EXAMPLE 3 Flotation conditions as in Comparison Example 1.

Collector: Styrenephosphonic acid The results of the test are shown in Table 2 where they are compared with the flotation results of collector mixtures according to the invention.

EXAMPLE 2 Flotation conditions as in Comparison Example 1.

Collector: Butylstannoate An alkyl glycoside of propylene glycoside reacted with a-dodecane epoxide was used as cocollector (2). The ratio of collector to co-collector in the mixture was 2:1.

The results of the test are shown in Table 2 where they are compared with the flotation results obtained where styrenephosphonic acid is used. Distinctly better flotation results in regard to recovery and selectivity can be obtained with the 2:1 mixtures of butylstannoate and alkyl glycosides than with styrenephosphonic acid.

EXAMPLE 3 Flotation conditions as in Comparison Example 1.

Collector: Butylstannoate An alkyl glycoside of propylene glycoside reacted with a-dodecane epoxide was used as cocollector (2). The ratio of collector to co-collector in the mixture was 1:2.

The results of the test are shown in Table 2 where they are compared with the flotation results obtained where styrenephosphonic acid is used. Distinctly better flotation results in regard to recovery and selectivity can be obtained with the 1:2 mixtures of butylstannoate and alkyl glycosides than with styrenephosphonic acid.

EXAMPLE 4 Flotation conditions as in Comparison Example 1.

Collector: Butylstannoate An alkyl glycoside of ethylene glycol glycoside reacted with a-dodecane epoxide was used as co-collector (3). The ratio of collector to co-collector in the mixture was 2:1. The results in Table 3 show that good flotation results can also be obtained with the ethylene glycol glycoside as cocollector (3) with butylstannoate.

COMPARISON EXAMPLE 4 Flotation conditions as in Comparison Example 1.

Collector: Butylstannoate A nonionic surfactant of an adduct of 2 moles ethylene oxide and 4 moles propylene oxide with 1 mole technical lauryl alcohol (0 to 3% C1O, 48 to 52% C12, 19 to 24% C14, 9 to 12% C16, 10 to 13% C,8, acid value 0, hydroxyl value 265-275; saponification value 1.2%, iodine value 0.5) was used as cocollector (4).

The results in Table 3 show that better flotation results are also obtained with the co-collector (3) than with the surfactant mentioned in Comparison Example 4.

Table 1 : Flotation of a South African cassiterite ore Dosage Fraction Rtotal RSnO2 Concentrate content (g/t) (%) (%) SnO2 SiO2 Fe2O3 Batch 1.1 58.0 7.2 Comparison Example 1 300* K 1 1.4 2.3 1.8 41.0 9.3 200 K 2 3.0 5.3 2.0 50.6 9.0 500 # 4.4 7.6 1.9 47.5 10.8 Batch 1.2 57.0 7.4 Comparison Example 2 300 K 1 10.4 14 1.6 55.6 8.3 100 K 2 2.8 4 1.5 53.4 9.0 400 # 13.2 28 1.6 55.1 8.5 Batch 1.2 56.8 6.7 Example 1 400 K 1 13.3 31 2.8 49.1 9.9 100 K 2 2.3 21 10.6 37.0 11.5 100 K 3 2.5 23 10.7 38.6 11.7 600 # 18.1 75 4.8 46.1 10.0 * Addition of MIBC as frother Table 2: Flotation of a South African cassiterite ore Dosage Fraction Rtotal RSnO2 Concentrate content (g/t) (%) (%) SnO2 SiO2 Fe2O3 Batch 1.6 62.5 10.1 Example 2 300 K 1 4.5 12 4.5 53.4 12.2 150 K 2 4.6 27 9.6 39.3 23.3 150 K 3 6.0 31 8.4 42.5 20.6 150 K 4 4.6 15 5.4 49.0 18.9 750 # 19.7 85 7.1 45.8 19.1 Batch 1.6 63.1 9.4 Example 3 350 K 1 13.5 42 5.1 56.1 12.1 150 K 2 7.4 43 9.5 47.4 19.1 500 # 20.9 85 6.7 53.0 14.6 Comparison Example 3 450 # 82 5.8 40.2 13.5 Table 3: Flotation of a South African cassiterite ore Dosage Fraction Rtotal RSnO2 Concentrate content (g/t) (%) (%) SnO2 SiO2 Fe2O3 Batch 1.5 57.7 9.5 Example 4 350 K 1 6.0 13 3.4 54.0 13.2 150 K 2 3.0 17 8.5 49.0 14.8 150 K 3 3.5 25 10.8 40.3 19.9 150 K 4 3.1 23 11.0 37.2 25.0 750 # 15.6 78 7.6 46.9 17.1 Batch 1.6 60.7 9.9 Comparison Example 4 750 K 1 1.6 2 2.1 49.6 15.6

Claims (11)

1. A process for the flotation of non-sulfidic ores, more especially cassiterite, wherein there is used as collector mixture a mixture containing (a) alkyl and/or alkenyl glycosides and (b) monoalkyl stannoates, the ratio of (a) to (b) being adjusted to a value of from 4:1 to 1:4.

2. A process as claimed in claim 1, characterised in that alkyl and/or alkenyl monoglycosides and/or polyglycosides containing from 1 to 8 glycoside residues, of which the alkyl or alkenyl radicals are linear or branched, contain from 2 to 18 carbon atoms and optionally contain a hydroxyl group and/or-instead of a -CH2-group-an ether bridge, are used.

3. A process as claimed in claim 1 or claim 2 characterised in that alkyl and/or alkenyl monoglycosides and/or polyglycosides containing from 1 to 3 glycoside residues are used.

4. A process as claimed in any of claims 1 to 3 characterised in that the monoalkylstannoates correspond to the following general formula RSn(O)OMe in which Me is sodium, potassium, hydrogen and R is a preferably linear saturated C2-C1O and preferably C2-C8 alkyl radical.

5. A process as claimed in claim 4, characterised in that the monoalkylstannoate is sodium monobutylstannoate.

6. A process as claimed in any of claims 1 to 5, characterised in that the mixture is used in quantities of from 100 to 1500 g per tonne crude ore.

7. A process for the separation of cassiterite from tin ores by flotation, in which ground ore is mixed with water to form a suspension, air is introduced into the suspension in the presence of a collector system and the froth formed is stripped together with the mineral therein, characterised in that (a) alkyl and/or alkenyl glycosides of the type defined in claims 1 to 3 and (b) monoalkylstannoates of the type defined in claims 4 and 5 are used as the collector system.

8. A process as claimed in claim 7, characterised in that the collector systems are used in quantities of from 100 to 1500 g per tonne crude ore.

9. A process as claimed in claim 1 substantially as herein described with reference to the Examples.

10. Non-sulfidic ores in particular cassiterite which have been subjected to a treatment as claimed in any of claims 1 to 9.

11. The use of a collector mixture in the flotation of non-sulfidic ores, more especially cassiterite, containing (a) alkyl and/or alkenyl glycosides and (b) monoalkyl stannoates, the ratio of (a) to (b) being adjusted to a value of from 4:1 to 1:4.