FI62006B - FOERFARANDE FOER SELEKTIV FLOTATION AV SULFIDISKA MINERALIER - Google Patents

Description

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(71) Outokumpu Oy, Outokumpu, FI; Töölönkatu U, 00100 Helsinki 10,

FIELD OF THE INVENTION This invention relates to a method for selectively foaming sulfide minerals, wherein the ore is first wet milled to flotation fineness, after which the resulting slurry is prepared and foamed.

In particular, this invention is directed to improving the flotation selectivity of sulfide minerals in a flotation process.

It is known that sulphide minerals can be foamed with good selectivity by using, for example, xanthate as a collector, the need for which is generally in the order of 50-500 g / t. The selectivity can be improved by using e.g. water glass as a silicate presser.

However, considerable difficulties arise with the above-mentioned known method in the treatment of many sulfide ores, especially nickel.

2 62006 The typical characteristics of such heavy ores are a very large specific surface area, which can be up to 10-100 times the specific surface area of a "healthy" ore ground to a corresponding fineness. This is mostly due to the strong degree of transformation or metamorphosis of the ore. As a result of metamorphosis, the particle size of the sulfide phase is often very small, which makes it necessary to grind the ore very finely in order to obtain a sufficient degree of refining. Metamorphosis often also results in a side stone, i.e. silicate material changed. Serpentine, chlorite and talc are quite common transformation results in this type of ore and are causing difficulties in the form of their softness, easy sludge and inherent hydrophobicity.

The large specific surface area, the sensitive sludge permeability of the harminer minerals, the inherent hydrophobicity and flocculability, and the small grain size of the sulfide minerals are the real causes of the problems. These result in e.g. an abnormally high collector demand, which is about ΙΟ times the above-mentioned normal consumption.

The need for other chemicals, such as HjSO 2 sn used in pH adjustment, is also very high. Despite the large amounts of chemicals and high costs, the flotation results remain weaker than with normal ore. This, of course, results in poorer profitability. In many cases, it is downright uneconomical to utilize the type of ore described by conventional methods.

It has now surprisingly been found that the above difficulties can be largely eliminated by the use of suitable additional chemicals.

The main features of the invention appear from the appended claim 1.

The invention is described in more detail below by means of examples.

Example 1

The first example of the results obtained by this method is the laboratory-scale results obtained at Malmi in a Ni mine.

3 62006

Test 1

Malini Rich Waste

% By weight 100 13.6 86.4

Ni% 0.61 3.0 0.23

Ni yield% 100.0 67.3 32.7

Test 2

Ore Rich Waste

Weight% 100.0 22.2 77.8

Ni% 0.62 2.5 0.10

Ni yield% 100.0 87.6 12.4

In Experiment 1, which has been carried out by a known conventional method, the following reagents have been used: I ^ SO ^ in (training and flotation, pH = 4) 24 kg / t K-anyyl xanthate (added to the training) 2 kg / t "Turpenso", foam (added to coaching) 300 g / t "Turpenso" is manufactured by Oy Enso-Gutzeit Ab, Finland, and has the following average composition: monoterpenes 35-55%, terpene alcohols 10-20% and sesquiterpenes 25-50%.

Experiment 2 has further used in accordance with the present invention

Polyglycol ether (added for coaching) 400 g / t

Alkylphenol ethylene oxide (added (for training) 400 g / t

In Experiment 2, the Ni yield is 20% units. better due to the chemicals added in accordance with this invention. In both of the above experiments, the grinding has been similar - ~ 70% - 74 μm and the experimental conditions are otherwise similar.

Example 2

Another example of the applicability of this method is the results obtained with a lower quality nickel ore in a nickel mine.

Test 3

Ore Rich Waste

Weight% 100 9.9 90.1

Ni% 0.40 2.5 0.17

Ni yield% 100 61.4 38.6

Experiment 4 4 62006

Ore Rich Waste

Weight% 100 19.7 80.3

Ni% 0.41 1.9 0.08

Ni yield% 100.0 85 ·, 2 14.8

Experiment 3 represents the level of result obtained by the conventional method and uses the following reagents: i ^ SOj ai (coaching + flotation, pH = 4) 29 kg / h K-amyl xanthate (added to coaching) 2 kg / h "Turpenso", foam (added to coaching) ) 300 g / t

Grinding fineness <v 70% - 74 μm

The result of Experiment 4 was obtained by the method of the present invention and in addition to the reagents of Experiment 3, the following reagents were used:

Polyglycol ether (added for coaching) 400 g / t

Dinonylphenol ethylene oxide (added for coaching) 400 g / t

Comparing these experimental results with each other, it is found that in the latter experiment 4 the Ni yield is about 24% unit due to the additional chemicals. better than in the previous experiment 3.

The increases in yield shown in Examples 1 and 2 mean a net yield of about FIM 8-15 / tonne of ore, which is of very significant economic importance in the utilization of such poor quality (average concentration / ** 0.5% Ni) ore.

Example 3

A third example of the advantages of the method of the present invention is another. an increase in Ni intake obtained with the difficult-to-use portion of nickel ore, as shown in the following table. Both Exemplary Experiments 5 and 6 were performed under otherwise similar conditions except that the latter used the additional chemicals mentioned below.

Experiment 5 5 62006

Ore Rich Waste

Weight% 100/0 10.6 89.4

Ni% 0.73 4.3 0.31

Ni yield% 100.0 63.7 36.3

Test 6

Weight% 100.0 16.9 83.1

Ni% 0.74 3.6 0.16

Ni yield% 100.0 81.2 18.8

The following conventional reagents have been used in Experiment 5: H2SO4 (coaching + flotation; pH = 4.5) 12 kg / t K-amyl xanthate (added to coaching) 300 g / t "Turpenso", foam (added to coaching) 450 g / t

In addition, the following reagents have been used in Experiment 6 according to the invention:

Polyglycol ether (added for coaching) 60 g / t

Nonylamine ethylene oxide (added for coaching) 100 g / t

Thanks to the additional chemicals, the Ni yield has increased by 17.5 percentage points, which means a net yield of about FIM 14 per tonne of ore for this type of Ore.

The above examples show very clearly that the factors mentioned in the introduction which degrade the enrichment results can be eliminated in a very simple way, with suitable additional chemicals. Additional chemicals have been added to the training in the above example experiments, but it is more preferable to add them already to grinding where the surfaces of the mineral granules are still "fresh" and the selectivity of the foaming is thus easier to maintain.

Example 4

The fourth example, in which the method according to the present invention has been tested on a factory scale, shows that it is possible to obtain a similar increase in yield on a production scale as above on a laboratory scale, which is in fact proof of the usefulness of the present invention. The figure in the accompanying drawing shows a graphical representation of the results of a factory-scale test run. The figure shows the nickel concentrations of the nickel intake and sulphide phase, concentrate, ore and waste using the method according to the invention (days 2-7) and the conventional known method (days 1 and 8-11) as a function of time, gradually switching from known method to method according to the invention and back . The measurement points are daily averages. The additives used and the degree of grinding are shown in the table below: 7 62006 rH O O ** rH (N ΓΟ ΙΠ

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It can be seen from the figure that the nickel content of the sulphide phase was over 10% during the test run (average 10.4%). This shows that it is a very difficult ore to concentrate when using the conventional method. This was also the case for the ore samples used as test materials in the first two examples; the nickel content of the sulfide phase was> 10%. Prior to the test run, the intake was at 50%. During the test run, the method according to the present invention was gradually introduced. In this way, the results improved all the time. The method according to the invention was in use for three days, with a yield of 66% (average). From this, it dropped to 47% when moving to the conventional method.

One advantage of the method according to the present invention is that the chemicals which improve the selectivity can be added as such to the process (grinding, training, etc. step) and, for example, expensive emulsifying devices are not required.

In addition, sludge density is an essential factor in the treatment of heavy sulfide ores of the type described above. So. the solids content of the sludge to be foamed, as a percentage by weight of the weight of the sludge, must be considerably lower (20-25%) than that of the corresponding ore in the case of healthy side rock (30-40% solids). This is because the side rock materials serpentine, chlorite, talc, etc., which cause the above-mentioned difficulties, easily cause flocculation and porridge of the ore slurry. This means an increase in the viscosity of the slurry, i.e. a deterioration in the flowability. This, in turn, results in the difficulty of mixing the flotation chemicals into the ore slurry, i.e. coaching time increases. Similarly, in the flotation step, dispersion of the flotation air in the slurry becomes difficult and is generally almost impossible by conventional methods if the slurry density is not reduced. The additional chemicals of this invention have the effect of improving the flow properties of the slurry, so that the slurry density does not need to be reduced as much as by conventional methods.

9 62006 At 25-30% sludge density flotation works well. This means savings / because the need for process water recycling is lower.

The addition of selectivity-enhancing chemicals to the milling step mentioned in the third example has been found in laboratory and factory-scale experiments to improve the result compared to the case where the chemicals are added to coaching. In addition, it has been found with sulphide ores that when flotation is carried out acidic, the addition of a collector (xanthate, thiophosphate, etc.) to a grinding or coaching step carried out in an alkaline or neutral environment followed by acidification of the slurry gives better results than adding an acidizer to acidification. In the factory-scale test run of the fourth example, said chemicals (including the collector) were initially added to the acid training. The result was considerably improved when the process according to the present invention was introduced and said chemicals were added to the alkaline milling, after which the slurry was only acidified.

In the above examples, reagents of the polyglycol ether-alkylphenol ethylene oxide and alkylamine ethylene oxide type have been used as selectivity-enhancing chemicals. A similar effect is obtained by using ethoxylated carboxylic acids, ethoxylated fatty alcohols and the like as a surfactant instead of the above-mentioned reagents, which removes the "collecting reagents" property of silicate surfaces while making them water-retaining so that they do not foam as much as without foaming the above-mentioned additional chemicals, thereby obtaining a much sharper distinction between desirable and undesired minerals.

Claims (3)

10 62006 A method for selectively foaming sulphurous minerals from silicates, wherein the ore is first wet milled to a flotation fineness, after which the resulting slurry is prepared and foamed in an acidic environment with a xanthate collector and an additional chemical, the anionic collector ethoxylated alkylphenol and / or ethoxylated alkylamine is used as an additional chemical, the additional chemical being added before or simultaneously with the collector to prevent the collector from adhering to the silicate surfaces and making them hydrophilic. Method according to Claim 1, characterized in that the pH of the mineral slurry is adjusted after the addition of the collector. Process according to Claim 1 or 2, characterized in that the additional chemical is used in an amount of at least 10% by weight, based on the amount of collector used, and preferably at most 40% by weight.