WO1993007110A1

WO1993007110A1 - Method of concentrating and or cleaning coal and minerals by flotation using hydroxyimone ethers

Info

Publication number: WO1993007110A1
Application number: PCT/EP1992/002260
Authority: WO
Inventors: Manfred Biermann; Holger Tesmann; Rita Köster
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1991-10-09
Filing date: 1992-09-30
Publication date: 1993-04-15
Also published as: DE4133388A1

Abstract

The invention enables minerals and coal to be concentrated and/or cleaned using a flotation process in which hydroxyimone ethers of the formula (Ia) and/or (Ib), in which R1 is a straight-chain or branched-chain alkyl group with 1 to 12 carbon atoms, a hydroxyethyl group or a hydroxypropyl group, are used as foaming agents, optionally mixed with other customarily used foaming agents and/or collecting agents.

Description

METHOD FOR ENLARGING AND / OR PURIFYING COAL AND MINERALS BY FLOTATION USING HYDROXYLLIMONE ETHER

Field of the Invention

The invention relates to a process for the enrichment and / or purification of coal and minerals by flotation, in which hydroxylimone ether is used as a foamer, hydroxylimone ether and a process for their preparation.

State of the art

Raw coal from mining in coal mining is processed to a large extent using the density differences. The raw coal is mechanically separated into coal fractions and a so-called recovery fraction. For the fine grain fraction (particle size smaller than 0.5 mm), flotation is preferred as a sorting process, with the fine grain coal being separated from the ash fraction due to the different surface properties of coal particles and rock particles. This takes advantage of the natural, water-repellent character of the surface of the carbon particles and reinforces it by adsorbing hydrophobic reagents. In suitable media The separation of fine grain coal and ash is possible using a flotation process and has also proven itself as an industrially used process. During the flotation, the fine carbon particles are bound to foam bubbles of a sufficiently stable foam produced by adding a foamer and thus removed from the slurry. The aim is to bring out the highest possible coal, but the ash content in the floated coal should be as low as possible, since this reduces the calorific value of the coal.

However, the effect of a so-called foamer is not limited to the simple generation of the foam. The type and amount of foaming agents can be used to control important foam characteristics, such as bubble size, bubble strength and cohesion of the bubbles. In the ore flotation, an influence of the foamer on the other components of the flotation slurry is usually observed. An influence of the foamer is undesirable if it acts unselectively on the collectors used in ore flotation, which change the hydrophilicity of the particle surface and should ensure better adhesion of the particles to the foam bubbles. It has therefore previously been desired to use only those foams whose properties only affect the stability and strength of the foam and also allow minimal consumption, but do not influence other process parameters [Ullmanns Encyclopedia of Industrial Chemistry, 4th edition, Verlag Chemie , Weinheim (1972), Volume 2, page 110 ff]. The minerals can be enriched through the successive application of individual flotation steps. For this purpose, the ore is crushed, preferably ground wet, and floated after adding the reagents necessary for the flotation. Appropriate adjustment of the slurry with regard to pH value, type and concentration of the collector, pusher and foamer enables a selective separation of valuable mineral and gait with high yield. In this context, it should be mentioned that an increase in the yield or selectivity by a few percentage points through appropriately selected reagent systems or improved flotation equipment can already be seen as a successful improvement with great economic importance, since the throughputs in coal and ore processing in the technical field are often in on the order of tens of thousands of tons of ore every day. A value mineral yield of several tons in a large-scale flotation process can therefore be regarded as very advantageous.

As part of the flotative enrichment of minerals or coal, it is advisable to use foams where there is no parallel orientation of the individual molecules. For this reason, substances with branched chains and asymmetrically arranged hydrocarbon groups are preferred. The optimal use of the foamer mentioned depends not only on the separation problem to be solved, but also - as stated above - on the other components present in the slurry, such as collectors, activators etc.

In German Offenlegaungsschrift DE-OS 19 30 671, for example, a method based on flotation is used Separation of minerals from ore is described in aqueous slurry, in which air is fed to the slurry containing a foamer and with the help of the resulting air bubbles, the removal of the valuable minerals is made possible. An adduct of ethylene oxide or propylene oxide with alcohols or glycols or their lower alkyl monoethers is used as the foamer.

The subject of German Offenlegungsschrift DE-OS 19 30 864 is a process in which the foamer represents the reaction product of ethylene oxide, propylene oxide or their mixtures with a polyhydric alcohol having at least 3 hydroxyl groups in the molecule. The foaming agents mentioned in the two aforementioned disclosure documents can be used both for the flotation of coal and for the flotation of a large number of ores and lead to a satisfactory discharge of the fractions, the enrichment of which is desired by the flotation process. When using conventional collectors, no adverse effect of the foamer on the properties of the collector in the flotation slurry was observed. However, the selectivity of some separation processes was not completely satisfactory, so that there was still a need for selective foaming agents which also lead to a high discharge of the desired fraction.

Flotation processes for coal using foaming agents are also known from European patent application EP 0 113 310 AI. Reaction products of a mono- or dibasic carboxylic acid with 1 to 10 carbon atoms and a polyhydroxy compound are used as foaming agents, the resulting ester alcohols having at least one free one Have hydroxy group. Substances which have branched alkyl groups and have a total number of 6 to 19 carbon atoms are preferably used.

From US Pat. Nos. 3,595,390 and EP 0 185 732 B1 the use of aliphatic alcohols, terpene alcohols, cresols and polyglycol ethers as foaming agents for the flotation of ores is also known.

The object of the invention was therefore an improved flotation process for enrichment and / or

To develop cleaning of coal and minerals that is free from the disadvantages described.

Description of the invention

The invention relates to a process for the enrichment and / or purification of minerals and coal by flotation, in which ground ore or coal is mixed with water to form a suspension, air is introduced into the suspension in the presence of a reagent system and the resulting foam together with the foam therein contained contained floated solids, which is characterized in that hydroxylimone ethers of the formulas (Ia) and / or (Ib),

in which R ^{1 is} a linear or branched alkyl radical having 1 to 12 carbon atoms, a hydroxyethyl or a hydroxypropyl radical, optionally in admixture with other commercially available foamers and / or collectors.

Surprisingly, it was found that reaction products of limonene epoxide with monohydric alcohols or diols, so-called "hydroxylimone ethers", have excellent properties as foaming agents not only in coal flotation, but can also be used as universally usable foaming agents in ore flotation. It was also shown that the The reaction products mentioned are not only compatible with other constituents of the flotation slurry, as is required for conventional foaming agents, but also have a positive effect on the influence of the collector in the flotation slurry, ie increase the collector effect and thereby reduce the amount used for those added as collectors Connections can contribute.

It has proven to be particularly advantageous. Use foamers of the formulas (Ia) and / or (Ib) in which R ^{1 represents} a linear or branched alkyl radical having 3 or 4 carbon atoms.

The hydroxylimone ethers can be used alone or in a mixture with other commercially available foams and / or collectors. Examples include aliphatic alcohols with 5 to 8 carbon atoms, carbinols, phenols, terpene alcohols, polyalkylene glycols and / or alkyl polyalkylene glycol ethers. Mixtures of hydroxylimone ethers with 2-ethylhexanol, ortho-cresol, pine oil, alpha-terpineol, methylisobutylcarbinol, polyethylene or polypropylene glycol ethers with average molecular weights of 300 to 3000, addition products of ethylene and / or propylene oxide onto aliphatic alcohols with 1 to 4 carbon atoms, gasoline fractions or mineral oils. The mixtures can contain the hydroxylimone ethers in amounts of 5 to 99, preferably 50 to 70% by weight, based on the mixture.

To achieve economically useful results in flotation, the foamer must be in a certain minimum amount be used. However, a maximum amount of hydroxylimone ethers must not be exceeded, since otherwise the foam formation becomes too strong and the selectivity towards the valuable minerals decreases.

The amounts in which the hydroxylimone ethers to be used according to the invention or their mixtures with other commercially available foaming agents are used depend on the type of material to be floated and on its content of valuable components. As a result, the amounts required can vary within wide limits. In general, the hydroxylimone ethers to be used according to the invention or their mixtures with other commercially available foaming agents are used in amounts of 5 to 1000, preferably 100 to 500 g, per ton of crude ore or coal.

The process according to the invention includes the use of reagents customary for flotation, such as collectors, regulators, activators, deactivators, etc. The flotation is carried out under the conditions of the methods of the prior art. In this context, reference is made to the following references on the technological background of ore processing: H. Schubert, "Processing solid mineral substances", Leipzig, 1967; D.B. Puchas (Ed.), "Solid / liquid separation equipment scale-up", Croydon, 1977; E.S.Perry, C.J. VanOss, E. Grushka (Ed.), "Separation and Purification Methods", New York, 1973-1978.

A preferred application of the method is the flotation of coal and sulfidic ores. While reaction products of limonene epoxide with ethanol are known, for example, from J. Org. Chem. 31, 1937 (1966), the higher hydroxylimone ethers are new substances. Another object of the invention therefore relates to hydroxylimone ethers of the formulas (Ia) and / or (Ib)

in which R ^{1 represents} a linear or branched alkyl radical having 3 to 12 carbon atoms, a hydroxyethyl or a hydroxypropyl radical.

Another object of the invention finally relates to a process for the preparation of hydroxylimone ethers of the formulas (Ia) and / or (Ib)

in which R ^{1 represents} a linear or branched alkyl radical having 3 to 12 carbon atoms, a hydroxyethyl or a hydroxypropyl radical, which is characterized in that limonene epoxide in the presence of linear or branched aliphatic alcohols having 3 to 12 carbon atoms, ethylene glycol or propylene glycol in subject to a ring opening reaction known per se.

The preparation of the hydroxylimone ethers to be used according to the invention is based on limonene epoxide, which is reacted at elevated temperature with the nucleophile - that is to say the alcohol or glycol. Typical examples of nucleophiles which are suitable for ring opening are n-propanol, isopropyl alcohol, n-butanol, i-butanol, sec-butanol, tert-butanol, pentanol, hexanol, heptanol, n-octanol, 2- Ethyl hexyl alcohol, decanol, dodecanol, ethylene glycol or propylene glycol. When the oxirane ring of limonene epoxide is opened, the two positionally isomeric vicinal hydroxyethers (la) and (Ib) are formed, the ratio of which is approximately 1: 1. The ring opening can be carried out at temperatures from 80 to 130, preferably 100 to 110 ° C and preferably in the presence of acidic catalysts, such as sulfuric acid or phosphoric acid; neutralization of the acid with a base, preferably sodium methylate, is then recommended. The reaction can take place in the presence of an inert organic solvent. However, it has proven to be optimal to use the nucleophile in excess instead of a solvent and then to remove unreacted starting material by distillation. With regard to the known ring opening of epoxides For example, reference is made to EP 0 361 080 AI.

The following examples are intended to explain the subject matter of the invention in more detail without restricting it.

Examples

Yes. Foamers of the formulas (la) and (Ib) according to the invention

Ib. Comparative foamers

X) methyl isobutyl carbinol (MIBC)

Y) Pine Oil

Z) 2-ethylhexanol Ic. General manufacturing instructions for foamers A to H

In a 1-1 three neck flask with dropping funnel. A stirrer and distillation attachment were placed in a mixture of 357 g (2.35 mol) of limonene epoxide (cis / trans mixture, 97% purity, from Alrich) and 7.5 mol of alcohol or alkylene glycol each and 0.3 g of concentrated sulfuric acid transferred. The reaction mixture was heated to 100 to 110 ° C. over a period of 40 to 60 minutes and, after cooling, neutralized by adding 2 g of sodium methylate. Excess alcohol or unreacted alkylene glycol was then distilled off in vacuo at 130 ° C. The hydroxylimone ethers were obtained in a compact, quantitative yield in the form of yellow-brownish, clear to slightly cloudy liquids.

Id. List of abbreviations used in the flotation examples (alphabetical)

AG = ash content of the floating material

AMX = amylxanthate (collector)

Bg = mountains

CUS = cupfer sulfate (modifier)

FS = flotation level

GA = total spread

IMX = isopropyl xanthate (collector)

Conc. = Concentrate

M = modifier

MAB = spread metal

MD = modifier dosage

MÖ = mineral oil

NAC = sodium cyanide (modifier)

S = sum (cumulative)

SA = collector

SAD = collector dosage

SCH = foamer

SD = foamer dosage

SGA = float

SNG = Snθ2 content

WAB = Apply mineral value

wf = anhydrous

Rpm = revolutions per minute

CNS = zinc sulfate (modifier) II. Coal flotation

The coal flotation was carried out in accordance with the working specification DIN 22 017. Of the six flotation levels prescribed in the regulation, three levels were carried out, since in particular the first flotation levels provide information about the effectiveness of the foamer to be examined; all foaming agents were added gradually and undiluted. The ash content was determined in accordance with DIN 51 719.

Fine grain coal (32% by weight ash, approx. 1.5% by weight total sulfur) with the following particle size distribution was used for the flotation tests:

Grain size distribution;

<25 by 21.9% by weight

25 to 100 μm 10.6% by weight

100 to 200 μm 14.7% by weight

200 to 315 μm 11.8% by weight

> 315 μm 41.0% by weight

Ash content of the flotation feed: approx. 31% by weight

The flotation was carried out in a KHD laboratory flotation cell MN 935/4 (volume: 2 l) with a solids concentration of 150 g / l water (16 ° d). From the 1st flotation stage, the material to be flotated was conditioned over a period of 1 min at a speed of 2000 rpm; from the second and third stages there was no conditioning carried out. The flotation was carried out in all three stages over a period of 1 min each at a speed of 2000 rpm. In addition to testing the pure foamer, combinations of the foamer with a naphthenic mineral oil (MÖ) were also tested, which are also used in coal preparation. The weight ratio of foamer / mineral oil is 1: 1 in all flotation examples. The results of the flotation are summarized in Table 1:

III. Flotation of non-sulfidic ores

The flotation task consisted of a cassiterite ore, which had the following composition:

1.0% by weight of SnO ₂

58.8% by weight SiO ₂

7.1% by weight of Fe ₂ O ₃

Wet sieving gave the following grain size distribution:

<25 μm: 49.5% by weight

25 to 63 μm: 43.8% by weight

63 to 80 μm: 4.9% by weight

> 80 μm: 0.9% by weight

The flotation was carried out in a Denver laboratory flotation cell, type Dl (volume: 1 1) with turbidity densities of approx. 400 g / 1 tap water (16 ° d); styrene phosphonic acid was used as a collector. The slurry was added at pH 7 to 8 as a pusher glass in a dosage of 2200 g / t. The preconditioning was carried out over a period of 15 minutes at a speed of 1500 rpm. The slurry was then adjusted to pH 5 with sulfuric acid, the collector and, if appropriate, the undiluted foamer were metered in and finally conditioned at 1500 rpm for a further 10 min. The flotation was carried out in two stages (6 min each, 1200 rpm) without a subsequent cleaning stage. The results are summarized in Table 2.

IV. Flotation of sulfidic ores

The flotation task consisted of a finely overgrown sulfide ore, which, in addition to sphalerite, pyrite, galena and chalcogenite, contained barite, carbonates and shale as the secondary rock. The composition was determined by X-ray fluorescence (average analysis):

8.5 wt% PbO

11.6% by weight Fe ₂ O ₃

21.0 wt% ZnO

2.7 wt% CuO

15.5 wt% BaO

The ore was ground to a flotation fineness in a simulated circular grinding in the bar mill. The following values were then obtained in the grain size analysis:

<25 μm 35.1% by weight

25 to 63 μm 13.9% by weight

63 to 100 μm 11.5% by weight

100 to 200 μm 29.5% by weight

> 200 μm 10.0% by weight

The laboratory flotations carried out for the foamer tests were carried out in a 1-1 Denver cell (cloud density approx. 500 g / l) with an ore feeder which was ground only to such an extent that the coarser overgrown minerals were sufficiently digested. In order to obtain salable concentrates during operational processing, post-grinding with further flotation levels is used there. Information on how to carry out the flotation is summarized in Table 3:

Pyrite was not separated. The foaming agents were added to the slurries undiluted. The composition of the flotation turbidity and the results of the flotation tests are summarized in Tables 4 and 5; the share of the mountains (Bg) results from the difference of the sum of the volumes applied in flotation stages I and II to 100% by volume.

Claims

Process for the enrichment and / or purification of minerals and coal by flotation, in which ground ore or coal is mixed with water to form a suspension, air is introduced into the suspension in the presence of a reagent system and the resulting foam is separated off together with the floated solids contained therein, characterized in that the foaming agent is hydroxylimone ether of the formulas (la) and / or (Ib),

in which R ^{1 is} a linear or branched alkyl radical having 1 to 12 carbon atoms, a hydroxyethyl or a hydroxypropyl radical, optionally in admixture with other commercially available foams and / or collectors.

Process according to Claim 1, characterized in that hydroxylimone ethers of the formulas (la) and / or (Ib) are used, in which R ^{1 represents} a linear or branched alkyl radical having 3 or 4 carbon atoms.

3. Process according to claims 1 and 2, characterized in that aliphatic alcohols having 5 to 8 carbon atoms, carbinols, phenols, terpene alcohols, polyalkylene glycols, alkylpolyalkylene glycol ethers, gasoline fractions and / or mineral oils are used as further commercially available foamers and / or collectors.

4. The method according to at least one of claims 1 to 3, characterized in that the foamer is used in amounts of 5 to 1000 g / t of crude ore or coal.

5. Hydroxylimone ethers of the formulas (Ia) and / or (Ib)

6. Process for the preparation of hydroxylimone ethers of the formulas (Ia) and / or (Ib)

in which R ^{1 represents} a linear or branched alkyl radical having 3 to 12 carbon atoms, a hydroxyethyl or a hydroxypropyl radical, characterized in that limonene epoxide in the presence of linear or branched aliphatic alcohols having 3 to 12 carbon atoms, ethylene glycol or propylene glycol per se subject to a known ring opening reaction.