FR2501072A1 - Froth flotation of minerals, esp. coal - using plant oil, esp. sunflower oil - Google Patents

Abstract

A mineral is purified by flotation using at least one oil from a plant source. Specifically the mineral is crushed coal and the oil is sunflower oil. Specifically the mineral is crushed, slurried with water, the plant oil added and the mixt. agitated. A frothing agent may be added. Concentrate from the first flotation may be further separated in a second flotation, opt. with addition of more oil. Shale etc. is removed. Coal with ash content about 10% can be used in a steelworks and coal with 15-20% ash content can be burnt in power stations. The plant oil can be produced locally and is not subject to restrictions which may be applied to kerosine or fuel oil.

Description

 The invention relates to a flotation method.

 It is known to use flotation processes to separate coal from a mineral matrix such as shale and pyrite. Generally, one begins by crushing the coal, then it is sieved and, then, the fine sieved coal is sent to a flotation tank after having treated it with a foaming agent and generally a collector. Examples of foaming agents used are alcohols. It is known to use kerosene and fuel oil as collectors.

 The invention relates to the use, in the flotation of minerals, of an oil extracted from plants. More particularly, the invention provides a mineral flotation process which consists in carrying out the flotation using at least one oil extracted from plants.

 A particular example of oil extracted from plants and which can be used is sunflower oil, extracted from the seeds of Helianthus annuusO Other oils are, for example, corn, soybean and cottonseed oils.

 The mineral to be subjected to flotation can advantageously be crushed coal. For example, one can crush the mineral such as coal, convert it into an aqueous slurry (for example having a concentration of 5 to 20% by weight) and add vegetable oil and also a foaming agent. Then, air can be injected through the slurry while stirring. The hydrophobic particles of carbon attach to the air bubbles formed in the slurry and are entrained on the surface, where they are removed by skimming. which has a high mineral content (i.e. ash) is practically unaffected by chemical reagents and, being heavier, sinks to the bottom of the slurry where it is removed. Generally, a carbon concentrate can be obtained having an ash content of only 5 to 10% by weight.

 The advantage of vegetable oil is that it can be produced locally and is therefore not subject to the restrictions that occasionally apply to mineral oils such as kerosene and fuel oil.

 The charcoal process can be applied to separate it into two float parts, one of which is suitable for the supply of a steelworks and has a low ash content, about 10%, and the other suitable for the supply of 'a power station and has an ash content of 15 to 20% O Coal can be subjected to a first flotation to obtain a concentrate (roughing foam) which can be subjected to flotation again. The concentrate subjected to the second flotation (called purifier float) can give a second foam concentrate (purifier foam) suitable for use in steelworks. The releases from the second concentrate (scrubber releases) can be used in the power plant.

 This double flotation is represented schematically by the appended drawing, which illustrates an embodiment of the invention.

 In the figure, raw coal is washed and the coarse coal is brought to a power plant and a steelworks. The washed fines obtained are subjected to the first flotation and the rejections from the first flotation are effectively waste. The first foam concentrate obtained is subjected to a second flotation. The second foam concentrate can be used for the steelworks, while the waste can be brought to the power plant.

In order to illustrate the invention, various experiments were carried out using two different methods. The methods of Examples 1 to 5 are set out below.
PROCESS I
We start by sieving a carbon with a 0.8 me sieve to remove coarse particles. 200 g are placed in a cell of a laboratory flotation machine
Denver and add water to obtain a total volume of slurry of 200 mlO The mechanical stirrer of the machine is lowered into the slurry, it is started and it is operated at a speed of about 1800 revolutions / min. Add a prescribed amount of collector and foaming agent and continue agitation for exactly 3 minutes (conditioning time).

At the end of this time, air is forced back into the slurry through the agitator blades. The bubbles formed then entrain the carbon particles on the surface.

where they are removed by skimming and collected in a flat container. The flotation time is 1 to 3 minutes. The coarse foam collected is diluted with additional water to obtain 4 to 7% of solids and the whole is placed in the same Denver flotation cell.

The agitator is placed in the slurry, it is started, then air is immediately forced back into the slurry, the foam formed is skimmed off and it is collected. The second flotation is also carried out for 1 to 3 minutes. The scum of the purifier is collected, the rejects remaining in the cell are filtered, they are dried, they are weighed and their ash content is determined.

PROCESS II
Process I is followed, except that a small amount of the same collecting system / foaming agent is added to the purifier 0.5 minutes before the introduction of air.

Following these processes, various experiments are carried out with
(a) a mixture of 90% by weight of sunflower oil and 10% by weight of methyl-isobutylcarbinol (hereinafter
MIBC), and
(b) 100% by weight of sunflower oil (therefore without addition of foaming agent).

 The experiments carried out and the results obtained are as follows: Examples 1, 2 and 3 are flotation experiments using sunflower oil.

Examples 4 and 5 use kerosene plus MIBC (controls). The comparison of the two series of tests shows that the vegetable oil gives results similar to those obtained with the petroleum product.

EXAMPLE 1
90% sunflower oil and 10%
MIBC, according to method I. Take 600 g of fine charcoal containing 33% ash and a size entirely less than 0.8 uit, which is divided into 3 equal portions of 200 g each; flotation is carried out respectively with 0.06 g, 0.08 g and 0.10 g of reagent (ie the equivalent of 0.3 kg / t 0.4 kg / t and 0.5 kg / t). The results below show that the products contain significantly less ash.

Addition of reagents l Flotation 0.06 g 0.08 g 0.10 g 2nd flotation None None None None
Yields
% in Ashes% in Ashes% in Ashes
weight, 'weight% weight%
Coal in 1st foam, coarser 37.9 11.4 46.5 12.1 58.5 13.4
Coal not floated in the scrubber 25.3 13.3 26.7 14.9 27.8 18.8
2nd floating coal 12.6 7.6 19.8 8.2 30.7 9.4
EXAMPLE 2
90% sunflower oil and 10% MIBC are used, according to method II.

 Take 600 g of fine charcoal containing 33% ash and a thickness entirely less than 0.8 mm, which is divided into 3 equal portions of 200 g each and the flotation is carried out respectively with 0.06 g, 0, 08 g and 0.10 g of reagent. For the second flotation of the scum, 0.02 g (0.10 kg / t) of additional reagent is added. This is done for each test. The results given below show a greater production of coal poor in ash in the foam from the 2nd flotation than in Example 1.

Addition of reagents 1st flotation 0.06 g 0.08 g 0.10 g 2nd flotation 0.02 g 0.02 g 0.02 g
Yields
in Ashes X in Ashes X in Ashes
weight% weight% weight%
Coal in floating ler, coarser 41.0 11.9 41.8 11.6 56.3 14.0
Coal not floated in the purifier float 15.4 17.3 12.8 17.2 17.9 21.3
Coal in the second foam 25.6 8.7 29.0 9.1 38.4 10.6
EXAMPLE 3
Process I is followed using 100% sunflower oil. Take 600 g of fine charcoal containing 33 X of ash and entirely lower than 0.8 a, which is divided into 4 equal portions of 200 g each and the flotation is carried out respectively with 0.10 g, 0.12 g , 0.14 g and 0.16 g (equivalent to 0.5 kg / t, 0.6 kg / t, 0.7 kg / t and 0.8 kg / t). after demonstrate that sunflower oil, while being a collector, also behaves as an effective foaming agent. The yield and the ash content are similar to those of Example 2, when an additional reagent is added in the 2nd flotation.

Addition of reagents
For the 1st flotation 0.10 g 0.12 g 0.14 g 0.16 g
For the 2nd flotation None None None None
Yields
% ashes% ashes% ashes% ashes weight% weight% weight% weight%
Coal in the 1st foam, coarser 41.4 12.4 41.3 12.6 45.8 13.2 50.5 13.9
Coal not floated in the purifier float 17.9 17.1 17.8 17.4 18.7 18.2 18.7 19.6
Coal in the second foam 23.5 8.8 23.8 9.0 27.1 9.8 31.8 10.5 EXAMPLE 4
90% kerosene and 10% MIBC are used according to method I. 600 g of fine charcoal containing 33 X of ash and a size entirely less than 0.8 mm is taken, which is divided into 3 equal portions of 200 g each and the flotation is carried out respectively with 0.10 g, 0.12 g and 0.14 g of reagent. The results are as follows t
Addition of reagents 1st flotation 0.1 g 0.12 g 0.14 g 2nd flotation None None None None
Yields
X in Ashes% in Ashes% in Ashes
weight% weight X weight%
Coal in the 1st foam, coarser 53.8 14.4 66.3 16.2 70.2 16.4
Coal not floated in the scrubber 49.3 14.9 52.4 18.2 48.8 19.6
Coal in the 2nd float 4.5 8.8 13.9 8.8 21.4 9.1
EXAMPLE 5
Process II is followed using 90% kerosene and 10% MIRO. Take 600 g of fine charcoal containing 33% ash and a size entirely less than 0.8 mm, divide into 3 equal portions of 200 g each and flotation is carried out respectively with 0.10 g, 0.12 g and 0.14 g of reagent. For the second flotation of the foam, an additional 0.02 g of reagent is added. The results are given below.
Addition of reagents 1st flotation 0.1 g 0.12 g 0.14 g 2nd flotation 0.02 g 0.02 g 0.02 g
Yields
% in Ashes% in Ashes% in Ashes
weight% weight% weight X
Coal in the 1st foam, coarser 53.0 13.5 67.0 16.9 71.0 16.7
Coal not floated in the scrubber 37.0 15.6 41.4 20.1 37.2 22.6
Coal in the 2nd float 16.0 8.6 25.6 9.3 33.8 10.3
EXAMPLE 6 - OPERATION IN A PILOT PLANT
Comparison of sunflower oil, with and without MIRO,
and a mixture of kerosene and MIBC (control),
as a coal flotation reagent.

 Fine coal (0.5 mm) from mine A is diluted in water, in a tank, to a solids content of 10% by mass.

 The coal slurry is pumped at a rate of 15 l / min to a conditioning tank with a volume of 85 liters, which gives a nominal residence time of 6 minutes. The flotation reagent is continuously pumped to the conditioning tank. The porridge then goes to a series of 8 flotation cells with a volume of 11 liters each. The foam from each cell is continuously scraped and collected separately from the rejects.

The reagents used are as follows:
(I) Lamp oil with methyl-isobutylcarbinol,
(MIBC), 10% mixture (comparison),
(II) Sunflower oil with MIRO, mixture at 10 s
(III) Sunflower oil alone.

 The reagent flow rate is adjusted so as to obtain a foam concentrate containing 9 to 12% ash.

The results of three roughing flotation are as follows:
Addition of foam concentrate
reagent,
Kg / t operation
n0 Rendering - Ash Reagent I
1 Tower oil - 0.32 54.5 9.5
2 nesol + MIBC 0.40 56.6 10.5
3 0.48 59.0 11.5
4 Tower oil - 0.62 37.0 9.5
5 nesol 0.72 47.2 10.5
6 0.86 61.5 11.5
7 Oil lam- 0.39 44.0 9.5
8 pant + MIBC, 0.46 47.0 10.5
9 witness 0.54 52.0 11.5
These results show a better yield, when using sunflower oil more MIBC, than kerosene oil more MIBC. With a larger addition of sunflower oil alone, the yield is greater than with lamp oil plus MIRO, the ash content being the same.

Claims (3)

 i o Flotation process for a mineral, characterized in that, for flotation, an oil consisting at least partially of sunflower oil is used.  2.- Method according to claim 1, characterized in that the mineral is a crushed coal.  3.- Method according to one of claims 1 and 2, characterized in that the mineral is crushed, it is diluted with water, the oil is added and optionally a foaming agent and carried out restlessness.