EP0108914B1 - Flotation adjuvant and method for the flotation of non-sulphidic ores - Google Patents

Abstract

Flotation aids and a process for the flotation of non-sulfidic minerals. The flotation aids have the formula <IMAGE> I wherein R repesents an aliphatic, cyclic, or alicyclic C7-C23 radical, optionally substituted with one or more hydroxyl, sulfhydryl, carbonyl, ether, or thioether groups; Xn+ is hydrogen or a water-solubilizing, salt-forming cation; and n is the valence of X. The invention also relates to ore suspensions and mineral concentrates in association with the above flotation aids.

Description

Numerous processes are known for the enrichment of non-sulfidic valuable minerals from ground raw ores by flotation. Such valuable minerals are, for example, apatite, fluorite, scheelite and other salt-like minerals, cassiterite and other heavy metal oxides, e.g. B. of titanium and zirconium, as well as certain silicates and aluminum silicates, the z. B. float in the presence of so-called collectors. Fatty acids, in particular unsaturated fatty acids such as oleic acid, are often used as collectors. Other suitable collectors are e.g. Sulfonate surfactants such as alkyl aryl sulfonates, sulfosuccinic acid monoalkyl esters or alkyl or aryl phosphonates.

However, such collectors based on fatty acids or sulfonates are known to be comparatively unselective, since they are also suitable for flotation of silicate and carbonate minerals and are therefore only of limited use if it is necessary to separate such accompanying minerals from other valuable minerals. It is therefore necessary to add further aids or complex reagent mixtures in order to suppress the undesirable gaits. In particular, selective flotation in the presence of calcite as a gangue therefore represents a technical problem for which collectors containing fatty acids or sulfo groups have disadvantages in practice.

The problems outlined are solved by the invention.

in der R einen aliphatischen, cyclischen oder alicyclischen Rest mit 7 bis 23 Kohlenstoffatomen und X⁺ ein Wasserstoffion oder ein wasserlöslich machendes, salzbildendes Kation bedeuten, als Sammler bei der Flotation nichtsulfidischer Minerale.The invention relates to the use of acyl lactylates of the formula

in which R is an aliphatic, cyclic or alicyclic radical having 7 to 23 carbon atoms and X ^{+ is} a hydrogen ion or a water-solubilizing, salt-forming cation, as a collector in the flotation of non-sulfidic minerals.

The preparation of acyl lactylates of the formula (I) is known; see Chemical Abstracts 55, 14 740i (1961); 60, 13803e (1964); 65, 619c (1966) and 80, 107951q (1974). Thereafter carboxylic acids or their functional derivatives such as acyl halides are mixed with lactic acid or salts of lactic acid, e.g. Sodium lactate, implemented at elevated temperatures. The removal of the water of reaction formed or other volatile reaction products such as hydrogen halide can be accelerated by working under reduced pressure, introducing inert gases or using solvents which form azeotropes. The use of suitable esterification catalysts can also be expedient. Processes are also useful in which acyl esters and lactic acid esters derived from lower alcohols, such as methanol, are transesterified with removal of the lower alcohol in the presence of transesterification catalysts. Depending on the composition of the starting mixture and reaction regime, oligomeric lactyl lactylates and esters of oligomeric lactyl lactylates are formed in addition to the acyl lactylates.

The reaction mixture can also contain minor amounts of unreacted starting material. These accompanying substances do not interfere with the use of the products according to the invention as flotation agents and can therefore remain in the product.

Suitable carboxylic acids which are esterified with lactic acid are aliphatic, cycloaliphatic, aromatic and alkylaromatic carboxylic acids with up to 24 carbon atoms. The carboxylic acids can contain linear or branched radicals and can also be substituted, for example by hydroxyl, sulfhydryl, carbonyl, ether or thioether groups. They are preferably derived from aliphatic, straight-chain, saturated or unsaturated carboxylic acids. Examples include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, undecenic acid, lauroleic acid, palmitoleic acid, oleic acid, elaidic acid, ricinoleic acid, linoleic acid, arachidonic acid, erucic acid, brassidic acid and clupanodonic acid. Mixtures of such fatty acids as are obtainable from naturally occurring fats of native or synthetic origin are usually used. Examples of native fatty acid mixtures are those obtained from tall oil, soybean oil, cottonseed oil, palm oil, coconut oil, sunflower oil, rapeseed oil, fish oil, tallow or castor oil.

Lactylates of unsaturated fatty acids and of mixtures of saturated and unsaturated fatty acids which have at least 25% by weight, preferably more than 50% by weight of mono- and / or di-unsaturated fatty acids, in particular oleic acid, have proven to be particularly suitable. Such oleic acid-rich mixtures can be obtained by known technical separation processes from native fatty acid mixtures, e.g. from sebum fatty acids in the desired technical purity.

Depending on the adjustment of the pH during flotation, the acyl lactylates can be present as free acids or as water-soluble salts. Suitable are salts of sodium, potassium, lithium and magnesium, further salts of ammonium and organic ammonium bases, e.g. B. salts of mono-, di- or triethanolamine, morpholine or guanidine. They are expediently used as sodium salts.

The lactylates derived from oleic acid-rich fatty acid mixtures which are preferably to be used are viscous liquids with very low pour points, that is to say below -10 ° to -20 ° C. This is compared to the known fatty acid collectors based on technical oleic acids, which are viscous to pasty Products act as an additional advantage, since - unlike pasty agents - they can be dosed much faster or more precisely even at low temperatures and can be homogeneously distributed in the mineral slurry. They also develop an intensive, load-bearing foam in the presence of alkaline earth metal ions, ie even when using hard water, which is why in many cases it is not necessary to add additional foamers or additional collectors.

The amounts of acyl lactylates to be used in the flotation are - depending on the nature of the ore to be flotated and the desired separation success - between 100 and 1000 g / t (grams per ton of ore). These amounts can also be exceeded, but the selectivity can decrease in the case of overdoses.

In addition to the acyl lactylates, other common collectors, frothers and other flotation aids can be used in the flotation, which in certain cases can improve the results even further. These include known anionic surfactants, such as fatty acids and other carboxylic acid derivatives, sulfonation products of fatty oils or fatty acids, mineral oil sulfonates, alkylbenzenesulfonates, alkane sulfonates, sulfosuccinic acid esters or half-esters, sulfosuccinic acid amides or half-amides, alkyl sulfates, alkyl ether sulfates, alkyl or alkyl dialkyl phosphates Dialkyl ether phosphates and alkylphenol ether sulfates. Known nonionic regulators, such as long-chain alcohols, alkylphenols and their ethoxylation products, can also be present. In order to maintain the high selectivity of the acyl lactylates, their proportion, based on the total amount of collectors and foaming agents present, should preferably be at least 25% by weight, in particular at least 40% by weight.

Furthermore, depending on the location of the processing problems and the plant technology, pH regulators may be present, as well as inorganic or organic depressants such as water glass, starch and starch derivatives, lignin-based reagents such as lignin sulfonates, dextrins, tannic acids and tannic acid extracts, cellulose derivatives such as carboxymethyl cellulose , Hydroxyethyl cellulose or methyl cellulose or other known protective colloids. The amounts used of these additives are within the ranges customary in flotation technology.

The invention furthermore relates to a process for separating non-sulfidic minerals from an ore by flotation with mixing ground ore with water to form an ore suspension, characterized in that air is added to the suspension in the presence of an amount of a compound of the formula (I) which is effective as a collector initiates and separates the desired minerals from the resulting foam.

The following examples are intended to show the superiority of the fatty acid lactylates to be used according to the invention over known collectors. It was worked under laboratory conditions with partly increased collector concentrations, which of course can be considerably undercut in practice. The possible uses and conditions of use are therefore not limited to the separation problems and test conditions given in the examples.

example 1

• Typ I: destillierte, aus Talgfettsäuren durch Phasentrennung gewonnene Ölsäure (Gehalt an gesättigten C_14-18-Fettsäuren ca. 15 Gew.-%).
• Typ 11: destillierte, von Harzsäuren weitgehend freie Tallölfettsäure (Harzgehalt unter 5%).

The following fatty acids were used to prepare the acyl lactylates:

• Type I: distilled oleic acid obtained from tallow fatty acids by phase separation (content of saturated C _14-18 fatty acids approx. 15% by weight).
• Type 11: distilled tall oil fatty acid largely free of resin acids (resin content below 5%).

Mixtures of the fatty acids with lactic acid in a molar ratio of 1: 1 were heated for 5 hours to temperatures of 150-160 ° C. while introducing pure nitrogen. The lactylates obtained had the following physical properties and analytical parameters (SZ = acid number, VZ = saponification number, JZ = iodine number):

The arrangement used for the flotation experiments consisted of a modified "Hallimond tube" according to B. DOBIAS in "Colloid & Polymer Sci. 259, 775-776 (1981), which had a volume of 160 ml. The apparatus was charged with 1.5 g of a ground phosphorite ore and a solution of the collector (type II) in a concentration of 28 mg / I corresponding to 3000 g / t. A concentrate was discharged while passing a nitrogen stream of 9.8 ml / min and stirring, which was analyzed as a function of time.

In a second series of experiments, the amount of collector used was reduced to 21 mg / l (2000 g / t).

Mineral used: phosphorite from a sedimentary deposit with a high calcite content, in which the following components were quantified:

The grain size distribution after desludging was:

The pH of the flotation solution was 9.5, the lactylate being in the form of the sodium salt. The results are summarized in Table I.

In the first column, the amount of the collector in g / t, in column 2, the flotation time in minutes, in column 3, the yield in percent by weight, based on the amount of P ₂ 0 ₅ submitted, and in column 4, the P ₂ 0 ₅ - reproduced the content of the applied concentrate.

After a short flotation time, a high proportion of the phosphate ore is released, the phosphate content of the ore sample becoming poorer as the test time progresses, so that the phosphate content of the ore applied also drops towards the end of the test period. Lowering the collector concentration increases the selectivity in favor of a higher phosphate content in the floated concentrate (2nd series of tests).

Table 2 shows the results of comparative tests. In experiment V ₁ sodium oleate, in experiment V2 sodium dodecylbenzenesulfonate, in experiment V ₃ a sodium sulfosuccinic acid monoalkyl ester (alkyl radical C _12-18 ) was used, each in a concentration of 3000 g / t ore. The collectors in experiments V ₁ and V ₂ are considerably less efficient than the compounds to be used according to the invention. In the comparative experiment V ₃ , the application rate is approximately less at approximately the same P ₂ 0 ₅ content in the concentrate or the required flotation time is considerably longer than in the experiment according to the invention, ie an application rate of m = 65% at a concentration content of c = 25% is only achieved after about 12 minutes, in the experiment according to the invention already after 2 minutes. After a 12-minute flotation time in comparative experiment V _3, the phosphate content of the raw ore used is not yet substantially depleted, which is why the content c in the concentrate is still relatively high at this point in time. This must be taken into account when comparing the test results.

Example 2

• 16,0% P₂0₅
• 6,2% CO₂
• 10,4% Si0₂
• 11,6% Mg0

An apatite ore was floated at 20 ° C. in a laboratory flotation cell (model D-1 from Denver Equipment) with a capacity of 1 liter. The raw ore contained carbonate, olivine and magnetite as the gait. After magnetic separation of the main amount of magnetite, the following contents were determined:

• 16.0% P ₂ 0 ₅
• 6.2% CO ₂
• 10.4% Si0 ₂
• 11.6% Mg0

The determination of the grain size distribution gave (in% by weight):

The flotation was carried out in one stage at a turbidity of 200 g / l, a speed of rotation of the mixing device of 1200 per minute, a pH of 11 and with the addition of water glass in an amount of 2000 g / t. 300 g / t fatty acid lactylate (Na salt, type II) were used as collectors. The flotation time was 4 minutes.

The same amount of sodium oleate was used in comparative experiment V ₄ . The higher selectivity of the lactylate over the oleate can be seen from the results listed in Table III.

Example 3

• 23,6% F^-
• 13,0% BaO
• 20,5% Si0₂

In the flotation apparatus used in Example 2, a fluorite ore was floated, which is predominantly grown together with barite, quartz and silicates as gait. The following contents were determined by analysis:

• 23.6% F ^-
• 13.0% BaO
• 20.5% Si0 ₂

At a turbidity of 350 g / l and a mixer speed of 1200 per minute, the flotation was carried out for 4 minutes. 500 g / t water glass, 200 g / t dextrin and 750 g / t lignin sulfonate were added as pusher. As a collector, oleic acid lactylate (Na salt, type I) was used as a comparison sample, sodium oleate (V _s ) and sodium alkyl ether phosphate (V ₆ ). The amount of use S of the collector in g / t, the pH of the solution and the test results (m based on weight percent fluorine) can be found in Table IV.

In the present case, too, the application rate m is significantly higher compared to the known means.

Example 4

• 1,0% Sn0₂
• 62,2% Si0₂
• 6,8% Fe₂0₃

As described in Example 2, a low-value cassiterite ore containing essentially granite, tourmaline and magnetite as gait was floated for 4 minutes at a turbidity density of 300 g / l. The following contents were determined by analysis.

• 1.0% Sn0 ₂
• 62.2% Si0 ₂
• 6.8% Fe ₂ 0 ₃

Grain size distribution:

Water glass was added as a pusher in an amount of 2200 g / t and the pH of the slurry was then adjusted to 5 using sulfuric acid. Oleic acid lactylate (Na salt, type I) was used as the collector, and oleic acid (V ₇ ), styrylphosphonic acid (V ₈ ) and the Na salt of a sulfosuccinic acid monoalkyl amide (Vg) were used as reference substances.

In this case too, the use of fatty acid lactylate with the same or only slightly reduced cassiterite content in the concentrate leads to a higher yield.

Claims (7)

1. The use of acyl lactylates corresponding to the following formula

in which R is an aliphatic, cyclic or alicyclic 6₇-0₂₃ radical and X⁺ is a hydrogen ion or a water- solubilizing, salt-forming cation, as collectors in the flotation of non-sulfidic minerals.

2. The use of the compound of formula (I) as a flotation aid as claimed in claim 1, characterized in that R is an aliphatic, linear or branched, saturated, mono- or polyunsaturated hydrocarbon radical optionally containing hydroxyl groups.

3. The use of the compounds of formula (I) as a flotation aid as claimed in claim 1, characterized in that the acyl radical RCOO is derived from linear fatty acids of which at least 25% by weight consists of mono- and/or polyunsaturated radicals.

4. The use of the compounds of formula (I) as flotation aids as claimed in claim 1, characterized in that X⁺ is an alkali metal, Mg or ammonium cation or the cation of an organic ammonium base.

5. A process for the separation of non-sulfidic minerals from an ore by flotation in which ground ore is mixed with water to form an ore suspension, characterized in that air is introduced into the suspension in the presence of a quantity of a compound of formula (I) active as collector and the desired minerals are separated off from the froth formed.

6. A process as claimed in claim 5, characterized in that the compound of formula (I) is used in a quantity of 100 to 2000 g/t ore.

7. A process as claimed in claims 5 and 6, characterized in that flotation is carried out in the presence of other standard collectors, frothers and depressors.