EP2012929B1 - Flotation reagent for minerals containing silicate - Google Patents

Abstract

The invention relates to the use of a compound of formula R—N-[A-NH2]2  (1) wherein R represents a linear or branched alkyl group or alkenyl group having 6 to 20 carbon atoms while A represents a C2 to C4 alkylene group, as collector in silicate flotation.

Description

The present invention relates to the use of alkyltriarnines in the flotation of siliceous minerals and ores.

In reverse flotation impurities are floated out of the value mineral. In particular, iron ore, calcium carbonate, phosphate and feldspar are often processed in this way. In many cases, siliceous minerals are the main constituents of these contaminants, causing quality degradation in the final product. These include quartz, mica and feldspar, as well as muscovite and biotite. For example, a high silicate content lowers the quality of iron ore concentrate, so that it is flotatively purified in Brazil, for example, by the use of alkyletheramines and alkylether diamines in order to be able to produce high-quality steels from the low-silicate concentrate.

Calcium carbonate is purified from silicate-containing and color-providing minerals with the aid of quaternary ammonium salts based on fatty acids or fatty alkylimidazoline compounds. Since calcium carbonate is used in addition to kaolin, rutile and talc as a white pigment in paper and plastic production, the highest possible whiteness or a low concentration of coloring minerals is desired. Due to the hardness of silicate, this would also lead to increased wear on the calenders of paper machines in papermaking. Therefore, calcium carbonate is purified in addition to dry processing via the flotation process.

In general, the aim is to reduce the silicate content, which in the case of calcium carbonate is often characterized as an acid-insoluble constituent, by less than 1.0% by weight due to the reverse flotation. The content of silicate in the task can vary and in some cases be from 10 to 20% by weight.

For example, fatty amines, alkyl ether amines, alkyl ether diamines or quaternary ammonium salt compounds are used as silicate collectors. These are also known under the trade name Flotigam ^®.

Alkyl ether amines and alkyl ether diamines are mostly used in their partially neutralized forms as partial acetates, as in U.S. 4,319,987 described. The reason for this is the better solubility of the partially neutralized amine functions.

The combination of a primary amine with a nitrogen-containing compound containing an anionic group is performed by U.S. 4,830,739 disclosed.

U.S. 4,995,965 describes the use of methyl bis (2-hydroxypropyl) cocosammonium methyl sulfate as a flotation reagent to float silicate-containing impurities out of calcite.

In U.S. 5,261,539 describes the use of alkoxylated alkylguanidines and alkoxylated amines for the reverse flotation of calcite.

In U.S. 5,540,336 shows the synergistic effect of ether amines and anionic collectors for iron ore floatation.

The silicate flotation, including iron ore, with the help of Alkyloxyalkanaminen is in U.S. 5,540,337 described.

U.S. 5,720,873 describes the combination of quaternary ammonium salts with fattyoxyalkylene compounds for the purification of calcium carbonate. This combination achieved an improvement over the quaternary ammonium salts in separating acid-insoluble components.

US Pat. No. 6,076,682 describes the combined use of alkylethermonoamine with alkyletherdiamine for silicate flotation from iron ore.

In WO-A-00/62937 discloses the use of quaternary amines for flotation of iron ore.

However, the silicate flotation collectors described in the prior art show insufficient results in terms of selectivity and yield. The object of the present invention was therefore to provide an improved collector for the silicate flotation, which can be used in particular in the reverse flotation but also in the direct flotation.

The collectors used today for the flotation of silicate-containing minerals have relatively high specific amounts used, which can lead to environmental problems with regard to the residual content of amine in the concentrate or in the mountains. It is known that amines and amine derivatives have high aqua and environmental toxicity. Therefore, one strives to minimize their specific amounts. Furthermore, their residual concentration in the final product should be kept as low as possible.

Surprisingly, it has been found that the use of alkyl dipropylene triamines leads to a marked improvement in the flotation of silicate-containing minerals compared to the known flotation reagents, it being possible to significantly reduce the specific amounts used.

The invention thus relates to the use of a compound of formula 1

RN- [A-NH ₂ ] ₂ (1)

wherein R is a linear or branched alkyl group or alkenyl group having 6 to 20 carbon atoms and A is a propylene group (-C ₃ H ₆ -), as a collector in the silicate flotation.

Another object of the invention is a method for flotation of silicate mineral by bringing a compound of formula 1 with the silicate-containing mineral in contact.

Another object of the invention is a composition containing 1 to 99 wt .-% of a collector for silicate flotation, which is an alkyl ether, alkyletherdiamine, alkylamine or quaternary ammonium salt, and 1 to 99 wt .-% of a compound of formula 1.

The compound of formula 1 is also referred to below as a collector according to the invention.

The collector according to the invention can be used alone or in combination with other nitrogen-containing compounds for the flotation of silicate, in particular iron ore, phosphate or calcium carbonate. Preferred nitrogen-containing compounds are alkyl ether amines, alkyl ether diamines, alkyl amines or quaternary ammonium salts.

The ratio of alkyletheramine, alkyletherdiamine, alkylamine or quaternary ammonium salt to compound of the formula is preferably between 95: 5 and 50:50 by weight.

R is a linear or branched hydrocarbon group. It is further preferred that R comprises 8 to 18 carbon atoms. Particularly preferred are 2-ethylhexyl, isononane, isodecane and Isotridekan- and dodecane radicals.

The silicate flotation collectors, which are an alkyl ether amine, alkyl ether diamine, alkyl amine or quaternary ammonium salt, and which may be used together with a compound of formula 1, are preferably one or more of the compounds of formulas (II) to (V) ).

These connections are

R ² -OR ³ -NH ₂ (II)

wherein R ^{2 is} a hydrocarbon group of 1 to 40, preferably 8 to 32 carbon atoms and R ^{3 is} an aliphatic hydrocarbon group of 2 to 4 carbon atoms;

R ⁴ -OR ⁵ -NH-R ⁶ -NH ₂ (III)

wherein R ^{4 is} a hydrocarbon group having 1 to 40, preferably 8 to 32 carbon atoms, R ⁵ and R ^{6 are} one or more aliphatic hydrocarbon group having 2 to 4 carbon atoms;

(R ⁷ R ⁸ NR ⁹ R ¹⁰ ) ⁺ B ^- (IV)

wherein R ⁷ , R ⁸ , R ⁹ and R ¹⁰ correspond to one or more hydrocarbon groups of 1 to 22 carbon atoms and B ^- a suitable anion;

R ¹¹ -NH ₂ (V)

wherein R ¹¹ corresponds to a hydrocarbon group having 1 to 40, preferably 8 to 32 carbon atoms.

The use of the flotation reagent according to the invention can also be carried out in combination with foaming agents and pushers, as known from the prior art. In order to avoid that in the case of silicate flotation from iron ore this is carried along, it is preferable to add hydrophilic polysaccharides, such as, for example, modified starch, carboxymethylcellulose or gum arabic in dosages of from 10 to 1000 g / t as a pusher.

The silicate flotation is preferably carried out at a pH of 7 to 12, in particular 8 to 11, which is set, for example, with sodium hydroxide.

The use according to the invention can be carried out both in direct and in reverse silicate flotation. The use according to the invention is also suitable for liberating silicate sand from impurities by flotatively separating the silicate sand from the impurities using the compound of formula 1.

Examples

Laboratory flotation experiments were performed using a Denver flotation cell.

Table 1 presents the flotative results of the collector B according to the invention in comparison to the standard reagent A. The flotation experiments were carried out on a silicate-containing calcium carbonate, the acid-insoluble constituents in the task accounting for 14.9%.

As standard reagent A, a dicocoalkyl dimethyl ammonium chloride was used. Table 1: Effectiveness of the collector B according to the invention in comparison with the standard collector A = dicocoalkyldimethylammonium chloride example collector Dosage in g / t Acid-insoluble components in calcite in% Whiteness in% 1 A 305 6.4 90.4 2 A 355 4.2 91.2 3 A 404 3.1 91.4 4 A 488 2.3 92.3 5 A 728 1.1 92.0 6 B 121 2.8 92.0

Notably, the reagent according to the invention in Example 6 already at a low dosage of only 121 g / t shows a much lower proportion of acid-insoluble constituents in the purified concentrate, which the standard reagent only reaches above 400 g / t. The reagent according to the invention behaves analogously with regard to the degree of whiteness. This is already at the low dosage 92.0, which is achieved with the standard reagent only with three to four times the amount used. Table 2: Effectiveness of a mixture of the collector B according to the invention and the standard collector A. example Collector A in g / t Collector B in g / t Acid-insoluble components in calcite in% Whiteness in% 7 222 25 4.45 92.0 8th 261 29 2.98 93.8 9 324 36 1.34 94.0 10 369 41 0.85 94.1 11 176 70 1.86 93.3 12 236 94 0.82 93.3 13 272 109 0.60 93.8 14 286 114 0.40 94.1 15 317 127 0.33 93.7 16 365 146 0.28 93.5

Examples 7 to 10 represent mixtures containing 10% of the collector B according to the invention and 90% of the standard collector A. Examples 11 to 16 show mixtures containing about 29% of the collector B according to the invention and about 71% of the standard collector A, represents.

The results in Examples 7 to 10 and 11 to 16 show a consistently lower proportion of acid-insoluble constituents and a higher degree of whiteness in the concentrate over the standard reagent in Examples 1 to 5.

The flotation reagent according to the invention can be used in a wide pH range, for example 6 to 12, preferably 6 to 8, and is added to the aqueous slurry in a concentration of preferably between 0.001 and 1.0 kg / ton of crude mineral.

With the flotation reagent according to the invention, a significant improvement in spreading and selectivity is achieved compared to the collectors of the prior art. Tables 1 to 2 show a significantly increased whiteness and a lower acid-insoluble content in calcite compared to the corresponding standard reagent.

Claims (13)

1. The use of a compound of the formula
   
           R-N-[A-NH₂]₂     (1)
   
   where R is a linear or branched alkyl group or alkenyl group having 6 to 20 carbon atoms and A is a propylene group (-C₃H₆-), as collector in silicate flotation.
2. The use as claimed in claim 1, wherein R is a linear aliphatic hydrocarbon moiety having 8 to 18 carbon atoms.
3. The use as claimed in claim 1 and/or 2, wherein R is a 2-ethylhexane, isononane, isodecane, decane, dodecane or isotridecane moiety.
4. The use as claimed in one or more of claims 1 to 3, for reverse flotation of silicaceous minerals from iron ore, phosphate ore or calcium carbonate.
5. The use as claimed in one or more of claims 1 to 4 for purifying silicate sand.
6. The use as claimed in one or more of claims 1 to 4 in the flotation of quartz, mica, feldspar or muscovite from iron ore, calcium carbonate or phosphate ore.
7. The use as claimed in one or more of claims 1 to 6 in the flotation of silicaceous minerals, wherein the ore contains between 0.1 and 50% by weight silicate.
8. The use as claimed in one or more of claims 1 to 7 in combination with frothers and depressants.
9. The use as claimed in one or more of claims 1 to 8 in a pH range of 7 to 12.
10. The use as claimed in one or more of claims 1 to 9 in amounts of 0.001 to 1.0 kg per tonne of crude ore.
11. The use as claimed in one or more of claims 1 to 10, wherein, in addition to the compound of formula 1, at least one further nitrogenous silicate collector selected from the group of alkyl ether amines, alkyl ether diamines, alkylamines and quaternary ammonium salts is present.
12. A composition containing 1 to 99% by weight of a collector for silicate flotation, which collector is an alkyl ether amine, alkyl ether diamine, alkylamine or quaternary ammonium salt, and also 1 to 99% by weight of a compound of the formula 1
    
            R-N-[A-NH₂]₂     (1)
    
    where R is a linear or branched alkyl group or alkenyl group having 6 to 20 carbon atoms and A is a propylene group (-C₃H₆-).
13. A process for the flotation of silicaceous mineral, which comprises bringing the silicaceous material into contact with at least one flotation reagent according to formula 1
    
            R-N-[A-NH₂]₂     (1)
    
    where R is a linear or branched alkyl group or alkenyl group having 6 to 20 carbon atoms and A is a propylene group (-C₃H₆-).