EP0270018B1 - Use of n-alkyl and n-alkenyl-aspartic acids as co-collectors for the flotation of non-sulfidic minerals - Google Patents

Abstract

Use of N-alkyl and/or N-alkenyl aspartic acids or salts thereof as co-collectors in the flotation of non-sulfidic ores and a process for the separation of non-sulfidic ores by flotation wherein N-alkyl and/or N-alkenyl aspartic acids or salts thereof are used in collector mixtures.

Description

The invention relates to the use of N-alkyl and / or N-alkenylaspartic acids as co-collectors in the flotation of non-sulfidic ores and a process for separating non-sulfidic ores by flotation.

Flotation is a generally used sorting process for the processing of mineral raw materials to separate valuable minerals from the gangue. Non-sulfidic minerals, such as apatite, fluorite, scheelite and other salt-like minerals, cassiterite and other metal oxides, such as titanium or zirconium oxides, as well as certain silicates and aluminosilicates can be prepared by flotation processes. For the flotation, the ore is pre-crushed and dry, but preferably ground wet and suspended in water. These suspensions are usually added to collectors, often in conjunction with auxiliary reagents such as foaming agents, regulators, pushers (deactivators) and / or stimulants (activators), in order to support the separation of the valuable minerals from the gangue components of the ore during the subsequent flotation. Before air is blown into the suspension (flotation), these reagents are usually allowed to act on the finely ground ore for a certain time (conditioning). As a result, a foam is generated on the surface of the suspension, the collector ensuring that the surface of the minerals is rendered hydrophobic. The minerals adhere to the gas bubbles formed during aeration, the hydrophobicization of the mineral components being carried out selectively in such a way that the undesired ore components do not adhere to the gas bubbles. The mineral-containing foam is stripped off and worked up using known methods. The aim of the flotation is to extract the mineral of value from the ores in the highest possible yield, while at the same time maintaining the best possible enrichment.

Anionic and cationic surfactants are mainly used as collectors in the flotative processing of non-sulfidic ores. These should adsorb as selectively as possible on the valuable mineral surface in order to achieve a high concentration in the flotation concentrate. In addition, the collectors should develop a stable, but not too stable, flotation foam. For ores containing gangue minerals from anionic collectors, e.g. Unsaturated and saturated fatty acids, especially tall oil fatty acids and oleic acids, alkyl sulfates or sulfonates, are not hydrophobicized, these are sufficient as collectors. For more difficult to float ores, such as tin ore, more selective collectors, such as Phosphonic acids (DD-C-76 974) or alkylsulfosuccinamides (US-A-3 830 366) are used.

Suitable organic phosphonates are water-soluble salts of organic phosphonic acids, for example salts of styrene phosphonic acid, for the flotation of non-sulfidic ores, in particular tin ores. as for example in X. International Mineral Proc. Congress - IMM, E. Töpfer, pages 626 to 627, London 1973 (0.S. Bogandow).

Collectors frequently used in the flotation of non-sulfidic ores are, for example, alkyl monocarboxylic acids, such as unsaturated long-chain fatty acids, such as the tall oil fatty acid mentioned above. However, di- and tricarboxylic acids are also used as flotation collectors (H. Schubert, H. Baldauf, A. Serrano, XII International Mineral Proc. Congress, Sao Paulo 1977).

From Soviet Inventions Illustrated v. 24.3.82, Derwent Publications Ltd., London, abstract 11362 and GB-A-2 037 619 the use of aspartic acid or its salts as collectors in the flotation of non-sulfidic ores (alunite, cassiterite) is known.

Many collectors for non-sulfidic ores develop a foam suitable for flotation because of their surfactant character. However, it may also be necessary to develop a foam by means of special foamers or to modify the foam in a suitable manner. Known foamers for flotation are alcohols with 4 to 10 carbon atoms, propylene glycols, polyethylene glycol or polypropylene glycol ethers, terpene alcohols (pine oils) and cresyl acids. If necessary, modifying reagents are added to the suspensions (turbidity) to be floated, for example regulators for the pH value, activators for the mineral to be obtained in the foam or pusher for the minerals undesirable in the foam and optionally also dispersants.

In many cases, the anionic and nonionic collectors used for the flotation of non-sulfidic ores do not lead to a satisfactory output of the valuable minerals with economically justifiable collector quantities.

The present invention was therefore based on the object of providing improved collectors in the sense of a more economical design of the flotation processes, with which larger yields of valuable minerals can be achieved either with constant collector quantities and constant selectivity, or constant mineral mineral yields with reduced collector quantities.

It has surprisingly been found that N-alkyl and / or N-alkenylaspartic acids can advantageously be used as co-collectors in the flotation of non-sulfidic ores.

The present invention relates to the use of N-alkyl and / or N-alkenylaspartic acids, the alkyl and / or alkenyl radicals of which are straight-chain or branched, have 8 to 18 carbon atoms and optionally a hydroxyl group and / or an ether bridge instead of a CH₂ group own, or their salts as co-collectors in the flotation of non-sulfidic ores.

In addition to the free acids of N-alkyl and N-alkenylaspartic acids, their alkali or ammonium salts can also be used advantageously. The corresponding potassium salts and preferably the corresponding sodium salts of N-alkyl and / or N-alkenylaspartic acids are advantageously used.

The preparation of N-alkyl and / or N-alkenyl amino acids and their alkali or ammonium salts is generally known from the literature. It takes place on the one hand by means of the various alkylation reactions on the nitrogen of the amino acid, as described for example in Houben-Weyl Volume 11/2, and on the other hand by the addition of primary or secondary amines to unsaturated carboxylic acids (J. March "Advanced Organic Chemistry: Reactions, Mechanism and Structure ", McGraw-Hill, 1977).

The latter process, starting from maleic acid esters, is used to prepare the N-alkyl and / or N-alkenylaspartic acids and salts referred to here. The maleic acid esters with the corresponding amine component can either be in a solvent (US Pat. No. 2,438,092) or solvent-free, optionally with the addition of a catalyst such as, for example, acetic acid, alkali metal thiocyanates or O, N-dialkylphosphocarbamates (SU-A-77 10 87) be implemented.

According to the invention, in addition to N-alkyl and / or N-alkenylaspartic acids in a ratio of 20: 1 to 1:20, anionic and / or nonionic collectors can also be used.

According to a preferred embodiment of the present invention, in addition to N-alkyl and / or N-alkenyl aspartic acids used as anionic collector tallow alkyl sulfosuccinamides and / or oleic acid.

A reaction product of propylene glycol glucoside with α-dodecane epoxide, for example, can advantageously be used as the nonionic collector.

The amounts in which the co-collectors to be used according to the invention are used depend in each case on the type of non-sulfidic ores to be floated and on their content of valuable mineral. As a result, the amounts required can vary within wide limits. In general, the co-collectors according to the invention are used in collector mixtures in amounts of 50 to 2000 g / t crude ore.

In practice, the N-alkyl and / or N-alkenylaspartic acids to be used according to the invention are used in combination with anionic, cationic and / or nonionic collectors in the known flotation processes for non-sulfidic ores instead of the known collectors. Accordingly, in addition to the collector mixtures, the customary reagents such as foaming agents, regulators, activators, deactivators, etc. are also added to the aqueous slurries of the ground ores. 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 ore processing technology: A. Schubert, Processing of Solid Mineral Raw Materials, Leipzig 1967; B. Wills, Mineral Processing Technology, New York, 1978; DB Purchas (ed.), Solid / Liquid Separation Equipment Scale-Up, Croydon 1977; ES Perry, CJ van Oss, E. Grushka (ed.), Separation and Purification Methods, New York 1973-1978.

The N-alkyl and / or N-alkenylaspartic acids to be used according to the invention can be used, for example, as co-collectors in the flotative processing of Scheelite ore, Cassiterite ore and Fluorite ore.

Another object of the invention is a process for the separation of non-sulfidic ores by flotation, in which ground ore is mixed with water to form an ore suspension, air is introduced into the suspension in the presence of the collector mixture and the resulting foam is separated off together with the mineral contained therein. This process is characterized in that N-alkyl and / or N-alkenylaspartic acids are used as co-collectors.

The following examples show the superiority of the co-collectors to be used according to the invention. Under laboratory conditions, increased collector concentrations were used in some cases, which in practice can sometimes be significantly lower. The possible uses and conditions of use are therefore not limited to the separation tasks and test conditions described in the examples. Unless otherwise stated, all percentages relate to percent by weight. The amounts of reagents are based on the active substance.

Manufacturing example

172 g of diethyl maleate were added dropwise to 259 g of technical tallow amine (16 to 18 carbon atoms) and 6 g of glacial acetic acid at 60 ° C., the internal temperature not exceeding 70 ° C. The reaction solution was 5 hours at 70 ° C leave and then heated to 90 ° C. 80 g of NaOH, dissolved in 970 ml of water, were added and the temperature was kept at 85 to 90 ° C. for 1 h.

Flotation attempts Examples 1 and 2 and Comparative Example 1

A Scheelite ore from Austria with the following chemical composition, based on the main components, was used as the flotation task: WO₃ 0.3% CaO 8.8% SiO₂ 55.8%

The ore sample has the following grain size distribution: 28% - 25 µm 43% 25-100 µm 29% 100-200 µm

Combinations of a sulfosuccinamide derived from a tallow amine with sodium salts of N-alkylaspartic acids in a weight ratio of 2: 1 were used as collector mixtures according to the invention. The chain length of the N-alkylaspartic acids was C _16/18 (example 1) and C _12/14 (example 2). The above-mentioned tallow alkyl sulfosuccinamide (Comparative Example 1) was used as a comparative collector.

The flotation experiments were carried out using a Humbold-Wedag laboratory flotation machine from KHD Industrieanlagen AG, Humbold-Wedag, Cologne (see Seifen-Fette-Wwachs 105) (1979), p. 248) in a 1 l flotation cell. Deionized water was used to make the slurry. The cloud density was 400 g / l. Water glass with a dosage of 2,000 g / t was used as the pusher. The conditioning time of the pusher was 10 min at a stirring speed of 2,000 l / min.

It was floated at the pH value of approximately 9.5 resulting from the addition of water glass. The type of collector dosage is shown in Table 1. The conditioning time of the collector was 3 minutes.

The results in Table 1 show that the collector combinations according to the invention achieve a significantly higher concentration and better yield than the alkylsulfosuccinamide of Comparative Example 1 alone.

Example 3 and Comparative Example 2

A valuable South African cassiterite ore was floated, which essentially contains granite, tourmaline and magnetite as a gait. The flotation task had the following grain size distribution: 49.5% - 25 µm 43.8% 25-63 µm 6.7% + 63 µm

The flotation experiments were carried out in a 1 1 laboratory flotation cell at room temperature. Water glass with a dosage of 2,000 g / t was used as the pusher, the pH of the slurry was adjusted to pH 5 with sulfuric acid before the addition of the collector. Flotation was carried out with a turbidity of 500 g ore per liter of tap water with a hardness of 16 ° dH. The flotation time of the pre-flotation was 4 min at a stirring speed of 1200 l / min.

The Na salt of N-tallow alkyl aspartic acid with a chain length of 16 to 18 carbon atoms was used as the co-collector according to the invention. A propylene glycol glucoside, reacted with α-dodecane epoxide, served as the collector. The mixing ratio of collector to co-collector was 1: 2 (example 3). Technical styrenephosphonic acid was used for comparative example 2.

Compared to styrene phosphonic acid, a higher SnO₂ content in the concentrate can be achieved with the co-collector according to the invention in combination with the alkyl glucoside, the metal output remaining the same despite lower collector dosing (Table 2).

Example 4 and Comparative Example 3

A Mexican fluorite ore was floated with predominantly silicates as gait. The flotation task had the following grain size distribution: 35% - 25 µm 50% 25 - 80 µm 15% + 80 µm

The pre-flotation concentrate was further ground before the subsequent cleaning stages. The grain size was then: 98% - 44 µm

The flotation experiments were carried out in a 1 1 Denver cell using extremely hard water (350 ° dH). The trigger was alkaline-digested starch with a dosage of 1,000 g / t.

The Na salt of N-tallow alkyl aspartic acid with a chain length of 16 to 18 carbon atoms in combination with oleic acid in a ratio of 1: 9 was used as the co-collector according to the invention (example 4). The standard collector was oleic acid (Comparative Example 3).

It can be seen from the results in Table 3 that the combination of the co-collector according to the invention with oleic acid results in better fluorite yield and a higher concentrate content with reduced dosage.

Claims (6)

1. The use of N-alkyl and/or N-alkenyl aspartic acids, in which the alkyl and/or alkenyl groups may be linear or branched, contain 8 to 18 carbon atoms and optionally bear a hydroxyl group and/or -instead of a CH₂ group - an ether bridge, or salts thereof as co-collectors in the flotation of non-sulfidic ores.
2. The use claimed in claim 1, characterized in that the potassium salts, ammonium salts and preferably the sodium salts of N-alkyl and/or N-alkenyl aspartic acids are used.
3. The use claimed in claims 1 and 2, characterized in that anionic and/or nonionic collectors are used in addition to the N-alkyl and/or N-alkenyl aspartic acids in a ratio of from 20:1 to 1:20.
4. The use claimed in claim 3, characterized in that tallow alkyl succinamides and/or oleic acid are used as anionic collectors in addition to N-alkyl and/or N-alkenyl aspartic acids.
5. The use claimed in claim 3, characterized in that a reaction product of propylene glycol glucoside with α-dodecane epoxide is used as nonionic collector in addition to N-alkyl and/or N-alkenyl aspartic acids.
6. The use claimed in claims 1 to 5, characterized in that the alkyl and/or alkenyl aspartic acids are used in collector mixtures in quantities of 50 to 2,000 g/t crude ore.