DESCRIPTION

The present invention relates to fatty acids as collector for beneficiation of phosphates from phosphate containing ores, their use in flotation processes and to a method for beneficia tion of phosphates using said collector.

BACKGROUND OF THE INVENTION

A majority of phosphate fertilizer supply is produced by processing sedimentary phosphate ores. The global depletion of easily accessible high-grade phosphate deposits leads to a ris ing demand of beneficiation technologies in phosphate ore processing, in order to make low-grade phosphate rock accessible as phosphate source. In principle, the phosphate con taining ores are processed to achieve an apatite concentrate, which is further processed to phosphoric acid and then into fertilizers. Typically, flotation processes, either direct and/or reverse flotation processes are applied for the beneficiation of phosphate containing ores and often several flotation stages are required. The froth flotation as separation technology in principle makes use of differences in hydrophobicity between the valuable desired mate rial and the waste gangue impurities. For phosphate ores, the type of phosphate deposit af fects the flotation performance. For sedimentary deposits of phosphate ores, the desired phosphate concentration can be achieved by flotation of silicate impurities from the finely ground phosphate containing ores (reverse flotation) when the gangue impurities essen tially consist of siliceous materials. For sedimentary phosphates with high carbonates, how ever, beneficiation of phosphate ores by separation of carbonate from phosphate presents especial difficulties since it requires a reagent selective between two chemically similar sur faces (apatite vs. calcite) (H. Sis et al., Minerals Engineering, 16 (2003) 577 - 585).

Both, direct apatite flotation (e.g. from igneous ores) and reverse flotation (flotation of the carbonate and/or silicate impurities contained in the phosphoric rock) typically use fatty acid-based collector systems as reagents to increase the differences in hydrophobicity be tween the desired and undesired material. The main primary collectors are based on partly unsaturated fatty acids (C ₁₂ -C ₁₈ ), which are employed at pH 4-5, with phosphoric acid as depressant. Since fatty acids are badly soluble in water at that pH, secondary collectors are used, typically anionic or nonionic surfactants, to improve selectivity and recovery. With these compounds a typical P ₂ 0 ₅ grade of up to 30 wt% can be achieved by flotation pro cesses starting with a typical sedimentary ore containing approx. 15 to 20 wt% P ₂ 0 ₅ . In par ticular, in the fertilizer industry however, P ₂ 0 ₅ content larger than 30 % is often required.

A typical flotation process for e.g. sedimentary phosphates requires a maximal selectivity in order to be able to adsorb on carbonate minerals (e.g. dolomite, calcite) but not on phos phates despite a very low adsorption contrast. The fatty acids typically used as primary col lector in the flotation industry derive from plant sources (e.g. vegetable oils, tall oils and similar) or animal source. However, such fatty acids used as a base for flotation collectors have a very strong variation in carbonate/phosphate selectivity depending on the chain length and degree of saturation depending on their sources.

US 4090972 discloses that the use of a secondary alcohol or an ethoxylated secondary alco hol in conjunction with conventional fatty acids in the flotation of non-sulfidic minerals re duces requirements for fuel oil usage. The useful fatty acids derive from vegetable or animal oil.

US 8657118 discloses a collector for the separation of phosphate by flotation of carbonates contained in non-sulfurous minerals, particularly phosphoric rock, preferably apatite. The collector comprises phosphoric ester.

WO 2016041916 discloses the use of branched fatty alcohol-based compounds selected from the group of fatty alcohols with 12-16 carbon atoms having a degree of branching of 1- 3, and their alkoxylates with a degree of ethoxylation of up to 3, as secondary collector for the froth flotation of non-sulfidic ores in combination with a primary collector selected from the group of amphoteric and anionic surface-active compounds. The use for reverse flota tion is not disclosed.

EP 0270933 discloses the use of branched fatty alcohols and their alkoxylates. The de scribed compositions in EP 0270933 are only suitable to achieve a grade of less than 31 % which may cause problems because of high dosing.

WO 2017162563 discloses a secondary collector mixture containing at least one compound selected from the group of branched fatty alcohols with 12-16 carbon atoms having a de gree of branching of 1 - 3.5 and their alkoxylates with a degree of ethoxylation of up to 4, and at least one compound selected from the group of alkoxylates of nonionic hydrocarbon compounds with a degree of ethoxylation of higher than 3 and carbohydrate-based surfac tants. Only non-ionic surfactants as co-collectors are disclosed.

US 4789466 discloses a process for separating non-sulfidic minerals from an ore by flota tion in which the ore is contacted with a mixture of (a) at least one adduct of ethylene oxide and propylene oxide with a C ₈ -C ₂₂ fatty alcohol and (b) at least one anionic, cationic or am- pholytic surfactant. Only binary collector compositions are disclosed.

Our older application PCT/EP2018/060455 describes a collector composition for beneficia- tion of phosphates from phosphate containing ores, their use in flotation processes and a method for beneficiation of phosphates using said collector composition, wherein a ternary mixture comprising oleic acid, iso-tridecanol ethoxylated with 3 EO and iso-tridecanol eth oxylated with 10 EO is described. Further, a ternary mixture comprising oleic acid, iso-tride canol ethoxylated with 3 EO and dioctyl sulfosuccinate is described. SUMMARY OF THE I NVENTION

In the light of the prior art the technical problem underlying the present invention was the use of collectors that overcome the disadvantages of those collectors known in the art. The collectors used in the present invention comprise unsaturated fatty acids in trans configura tion, the collector compositions are at least binary compositions that are suitable for flota tion processes, show increased selectivity, offer the possibility of dose reduction and can be used for beneficiation of phosphate from phosphate containing ores. The process for flota tion enables short process times and overcomes the disadvantages known in the art.

The problem is solved by the features of the independent claims. Preferred embodiments of the present invention are provided by the dependent claims.

The invention therefore relates to a collector composition for beneficiation of phosphates from phosphate containing ores comprising i. at least one component A, and

ii. at least one component B, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants.

In a preferred embodiment the collector composition for beneficiation of phosphates from phosphate containing ores comprises at least one component A,

i. at least one component B, and

ii. at least one component C, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants which comprise two differ ent types of alkoxy moieties, and wherein the component C comprises alkoxylated alcohols or sulfur-containing surfactants.

In a preferred embodiment the component A comprises at least 70 % unsaturated fatty ac ids with 16 to 18 carbon atoms, which have an unsaturation degree of 0.5 to 3.

In a preferred embodiment the component A comprises at least 70% unsaturated fatty acids with 18 carbon atoms, which have an unsaturation degree of 1.

In a preferred embodiment the component A comprises at least 70 % unsaturated fatty ac ids with 16 to 18 carbon atoms and an average unsaturation degree of 0.7 to 3. In a preferred embodiment the component A comprises at least 70% unsaturated fatty acids with 18 carbon atoms and an average unsaturation degree of 0.7.

In a preferred embodiment the unsaturated fatty acids in the collector composition com prise a blend of elaidic acid in trans configuration and oleic acid in cis configuration.

In a preferred embodiment the at least 1 % of the unsaturated fatty acids in trans configura tion is elaidic acid.

In a preferred embodiment component A comprises less than 15 % saturated fatty acids and less than 15 % unsaturated fatty acids with an unsaturation degree of at least 2.

In a preferred embodiment the component B comprises two different types of alkoxy moie ties.

In a preferred embodiment alkoxylated alcohols of component B have 9 to 18 carbon atoms, have a degree of ethoxylation in the range of 2 to 10, have a degree of propoxylation in the range of 1 to 10 and are linear or branched.

In a preferred embodiment the collector composition comprises an additional component C, which comprises anionic surfactants or non-ionic surfactants, which are different to compo nent B.

In a preferred embodiment the collector composition comprises an additional component C, which comprises sulfur-containing surfactants as anionic surfactants or comprises alkox ylated alcohols as non-ionic surfactants, which are different to component B.

In a preferred embodiment the component C is selected from the group consisting of sul- fonated fatty acids, dialkyl sulfosuccinates, di- or tetraalkyl sulfosuccinamates, sodium do- decyl sulfate, dioctyl sulfosuccinate, alkyl ether sulfates, alkyl benzenesulfonates, alkyl sul fates of the formula C _n H _2n+1 0S0 ₃ with n = 12 to 22.

A further aspect of the invention relates to the use of the collector composition for benefi- ciation of phosphates from phosphate containing ores comprising i. at least one component A, and

ii. at least one component B, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants. In a preferred embodiment the collector composition of the present invention relates to the use of the collector compositions for beneficiation of phosphates from phosphate contain ing ores, wherein the collector composition comprises i. at least one component A,

ii. at least one component B, and

iii. at least one component C, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants which comprise two differ ent types of alkoxy moieties, and wherein the component C comprises alkoxylated alcohols or sulfur-containing surfactants.

In a preferred embodiment the collector composition of the present invention is used for di rect flotation of phosphates by collecting phosphate in the froth.

In a preferred embodiment the collector composition of the present invention is used for re verse flotation of phosphates by collection of impurities from phosphate containing ores in the froth.

In a preferred embodiment the collector composition is used for beneficiation of phosphates by flotation from sedimentary phosphate containing ores and/or from igneous phosphate containing ores.

The invention further relates to a flotation process for beneficiation of phosphates from phosphate containing ores comprising the collector composition according to the present invention.

In a preferred embodiment the flotation process according to the present invention is a di rect flotation of phosphates, comprising the steps

Comminution of ores,

Optionally, conditioning of ores with depressants and/or activators,

pH adjustment,

Collector addition,

Flotation,

Collection of phosphate in the froth.

In a preferred embodiment the flotation process according to the present invention is a re verse flotation of phosphates by collection of impurities from phosphate containing ores in the froth, comprising the steps Comminution of ores,

Optionally, conditioning of ores with depressants and/or activators,

pH adjustment,

Collector addition,

Flotation,

Collection of carbonate minerals and/or other impurities in the froth,

Recovering of phosphates from the cell product.

In a preferred embodiment, in the flotation process according to the present invention the phosphate containing ores are pretreated to remove silicates.

In a preferred embodiment, in the flotation process according to the present invention one or more modifiers and/or one or more frothers and/or one or more depressants are used.

DETAILED DESCRI PTION OF THE INVENTION

Specifically, it can be stated that the invention relates to a collector composition for benefi- ciation of phosphates from phosphate containing ores comprising i. at least one component A, and

ii. at least one component B, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants.

Surprisingly, it was found that unsaturated fatty acids in trans configuration are significantly more suitable to achieve high selectivity in froth flotation for beneficiation of phosphates when used as primary collector. A collector of equivalent composition using a tallow derived fatty acid has shown a better selectivity at the same dosage in comparison to various plant based fatty acids. The main difference between tallow fatty acid and plant based oleic acid materials is that about 10% of the tallow fatty acid is a trans isomer of oleic acid, called elaidic acid. The higher content of elaidic acid in the fatty acid resulted in a better selectiv ity without any penalties to other aspects of collector performance (e.g. recovery, dose effi- cency). High elaidic fatty acids are prefereably be used as main component for selective flo tation collectors for reverse flotation (collection of carbonate impurities in the froth). Elaidic acid fractions of fatty acid may derive from tallow fat (e.g. cattle or sheep fat), produced as a waste stream in meat production, or may be generated through high temperature conver sion of unsaturated fatty acids in cis configuration.

Further preferred is that the collector composition for beneficiation of phosphates from phosphate containing ores comprises i. at least one component A,

ii. at least one component B, and

iii. at least one component C, wherein the component A comprises unsaturated fatty acids having 12 to 22 carbon atoms and at least 1 % of the unsaturated fatty acids is in trans configuration, wherein the compo nent B comprises alkoxylated alcohols as non-ionic surfactants which comprise two differ ent types of alkoxy moieties, and wherein the component C comprises sulfur-containing surfactants.

As used herein, the term“phosphoric rock” or“phosphoric ore” relates to the ore sources, which in particular comprises phosphates. Phosphates are the desired or valuable material or mineral, which can be part of sedimentary phosphate deposits or igneous phosphate de posits.“Phosphate rock” or“phosphoric ore” falls under the general term of “non-sulfidic ores”.

As used herein, the term“impurities” relates to undesired material or mineral as component in phosphoric rock. The undesired material is also named gangue or waste. Impurities may comprise for example carbonates, in particular called carbonate minerals (e.g. calcite, dolo mite), silicates, and/or scheelite. Impurities can also comprise silicate minerals such as quartz, feldspar or syenite minerals, layered silicates (micas, clays) or organic materials.

The typical composition of phosphates preferably comprises different subtypes of apatite structure, such as for example fluoroapatite, hydroxoapatite, carbonatoapatite, chloroap- atite or their combinations, also known as frankolyte.

As used herein, the term“flotation” relates to the separation of minerals based on differ ences in their hydrophobicity and their different ability to adhere or attach to air bubbles. Aim of flotation as mineral processing operation is to selectively separate certain materials. In particular, the flotation is used for beneficiation of phosphates from phosphate contain ing ores. Flotation comprises froth flotation methods like for example direct flotation or re verse flotation. Direct flotation of phosphates refers to methods where in particular phos phates are collected in the froth and the impurities remain in the slurry. Reverse flotation or inverse flotation of phosphates relates to methods where the impurities as undesired mate rials are collected in the froth and the phosphates remain in the slurry as cell product. In particular, reverse flotation of phosphates is similar to direct flotation of carbonates. Cell product has the similar meaning as cell underflow or slurry and means the product remain ing in the cell in particular in reverse flotation processes. Froth product means the product obtained in the froth in particular in direct flotation processes. The term“concentrate” has the meaning of flotation product and refers to the material obtained as cell product (valua ble material) in reverse flotation processes as well as to froth product as the material ob tained in the froth (valuable material) in direct flotation processes. The term tailings or flo tation tailings is understood economically and means the undesired product, impurities which are removed in direct or reverse flotation processes. As used herein, the term“collector” relates to substances with the ability to adsorb to an ore particle and to make the ore particle hydrophobic in order to enable that the ore parti cles can attach to air bubbles during flotation. The collector may comprise for example at least one or two or three different collectors. A collector composition may comprise collec tor components which are named for example primary, secondary, ternary collector and can influence the collector composition properties. A collector composition comprises in particu lar mixtures of fatty acids and surfactants. The collectors can in particular be surface active, can have emulsification properties, can act as wetting agent, can be a solubility enhancer and/or a foam or froth regulator.

As used herein, the term“grade” relates to the content of the desired mineral or valuable or targeted material in the obtained concentrate after the enrichment via flotation. In particu lar, grade is the concentration of P ₂ 0 ₅ obtained by the phosphate flotation process. The grade in particular refers to the P ₂ 0 ₅ concentration and describes the content of P ₂ 0 ₅ in the concentrate (w/w), particularly in the froth product at direct phosphate flotation and the content of P ₂ 0 ₅ in the cell product in reverse phosphate flotation.

As used herein, the term“recovery” refers to the percentage of valuable material recovered after the enrichment via flotation. The relationship of grade (concentration) vs. recovery (amount) is a measure for the selectivity of froth flotation. The selectivity increases with in creasing values for grade and/or recovery. With the selectivity the effectiveness / perfor mance of the froth flotation can be described.

Preferably the collector comprising unsaturated fatty acids in trans configuration of this in vention is used in the mining industry for mineral processing by in particular froth flotation processes for separating desired minerals from gangue and impurities. It is an advantage that by using the collector comprising unsaturated fatty acids in trans configuration accord ing to the present invention differences in hydrophobicity between desired (valuable) min eral, in particular phosphates, and impurities (waste, gangue), in particular carbonates, are increased. When using the collector comprising unsaturated fatty acids in trans configura tion of the present invention, a selective separation of in particular the minerals phosphates and carbonates is possible. The present collector comprising unsaturated fatty acids in trans configuration makes complex ore mixtures comprising for example phosphates, sili cates, carbonates and optionally other impurities accessible for beneficiation of phosphate. By using the collector comprising unsaturated fatty acids in trans configuration of the pre sent invention, processing of complex ores, which contain impurities or undesired ores, for example carbonates in phosphate ores, becomes economically feasible. It is possible to use the collector comprising unsaturated fatty acids in trans configuration in flotation processes for the separation of large ranges of carbonates and silicates prior to further refinement.

The collector comprising unsaturated fatty acids in trans configuration can in particular be used to upgrade (purify) phosphates by flotation technology, in particular by froth flotation processes. With the use of the present collector comprising unsaturated fatty acids in trans configuration, complex processes can be avoided and the enrichment of phosphate for sub sequent use in fertilizers is possible. The collector comprising unsaturated fatty acids in trans configuration can in particular be used for phosphate containing ores which were up to now not suitable for the beneficiation of phosphates.

Preferably the collector comprising unsaturated fatty acids in trans configuration is used for direct flotation of phosphates by collecting phosphate in the froth. It is further preferred, that the collector comprising unsaturated fatty acids in trans configuration is used for re verse flotation of phosphates by collection of impurities from phosphate containing ores in the froth. Also preferred is that the collector comprising unsaturated fatty acids in trans configuration is used for flotation of phosphates from sedimentary phosphate containing ores and/or from igneous phosphate containing ores. Concentrates produced by flotation from sedimentary ores for examples comprise <1% MgO, >30% P ₂ 0 ₅ , <4% Si0 ₂ . Concen trates produced by flotation from igneous ores for example comprise <1% MgO, >35% P ₂ 0 ₅ , <2% Si0 ₂ . Preferably, sedimentary phosphate containing ores are processed by direct flota tion or by reverse flotation using for example the collector comprising unsaturated fatty ac ids in trans configuration of the present invention. It is preferred, that igneous phosphate containing ores are for example processed by direct flotation using in particular the collec tor comprising unsaturated fatty acids in trans configuration of the present invention.

Preferably, the collector comprising unsaturated fatty acids in trans configuration is in par ticularly a primary collector, presently also named component A, and may additionally com prise fatty acids or derivatives thereof, which are for example saturated and/or unsaturated fatty acids with at least 12 carbon atoms. Preferably the fatty acids or derivatives thereof comprise 12 to 22 carbon atoms, more preferably 14 to 20 carbon atoms and most prefera bly 16 to 18 carbon atoms. Also preferred is a component A, which comprises a fatty acid blend of 12 to 22 carbon atoms with more than 50 % C12 fatty acids. Further preferred is that component A comprises a fatty acid blend with 90% or more C ₁₆ to C ₁₈ fatty acids and with an average unsaturation degree of 0.5 to 3. The meaning of for example“fatty acids with 12 to 22 carbon atoms” is similar to the meaning of for example“C12 to C22 fatty ac ids”.

It is preferred, that the component A is a natural product from animal source. Also possible is that blends of fatty acids from plant or vegetable source and animal source are used as primary collector in froth flotation for beneficiation of phosphates from phosphate contain ing mineral ores. The main source of component A is tallow (animal source), which may also be used in a blend in combination with tall oil (wood pulp side product), palm oil and/or other vegetable oils. In particular, component A is a blend or mixture of fatty acids. For ex ample, a blend of saturated and unsaturated fatty acids is possible. In particular, a blend comprising unsaturated fatty acids with a certain ratio of cis- and trans-fatty acids is used for flotation.

Preferably, the amount of unsaturated fatty acids as part of component A in relation to the total amount of component A is at least 50% (wt./wt.), at least 55% (wt./wt.), at least 60% (wt./wt.), at least 65% (wt./wt.), at least 70% (wt./wt.), at least 75% (wt./wt.), at least 80% (wt./wt.), at least 85% (wt./wt.), at least 90% (wt./wt.), or at least 95% (wt./wt.). Preferably, the amount of C18 mono-unsaturated fatty acids as part of component A in rela tion to the total amount of component A is at least 50% (wt./wt.), at least 55% (wt./wt.), at least 60% (wt./wt.), at least 65% (wt./wt.), at least 70% (wt./wt.), at least 75% (wt./wt.), at least 80% (wt./wt.), at least 85% (wt./wt.), at least 90% (wt./wt.), or at least 95% (wt./wt.).

Preferably, the amount of fatty acids in trans configuration in relation to the amount of un saturated fatty acids of component A is at least 1% (wt./wt.), at least 2% (wt./wt.), at least 3% (wt./wt.), at least 4% (wt./wt.), at least 5% (wt./wt.), at least 6% (wt./wt.), at least 7% (wt./wt.), at least 8% (wt./wt.), at least 9% (wt./wt.), at least 10% (wt./wt.), at least 11% (wt./wt.), at least 12% (wt./wt.), at least 13% (wt./wt.), at least 14% (wt./wt.), at least 15%

(wt./wt.), at least 16% (wt./wt.), at least 17% (wt./wt.), at least 18% (wt./wt.), at least 19%

(wt./wt.), or at least 20% (wt./wt.).

Preferably, the amount of elaidic acid in relation to the amount of unsaturated fatty acids of component A is at least 1% (wt./wt.), at least 2% (wt./wt.), at least 3% (wt./wt.), at least 4% (wt./wt.), at least 5% (wt./wt.), at least 6% (wt./wt.), at least 7% (wt./wt.), at least 8% (wt./wt.), at least 9% (wt./wt.), at least 10% (wt./wt.), at least 11% (wt./wt.), at least 12% (wt./wt.), at least 13% (wt./wt.), at least 14% (wt./wt.), at least 15% (wt./wt.), at least 16%

(wt./wt.), at least 17% (wt./wt.), at least 18% (wt./wt.), at least 19% (wt./wt.), or at least

20% (wt./wt.).

The component A (primary collector) for example may contain different side products. Such side products may have an influence on the performance of the component A as collector in froth-flotation of non-sulfidic ores in particular during direct and/or reverse flotation of phosphates from phosphate containing ores. A blend comprising elaidic acid is a preferred substance for component A. Additional substances in the primary collector blend are exam ple tall oil fatty acids (TOFA). Tall oil can be obtained as wood pulp side product. Tall oil comprises for example a fatty acid blend of oleic acid, linoleic acid, conjugated linoleic acid, stearic acid and for example other fatty acids and/or other components. The primary collec tor may comprise rosins in addition to the fatty acids or the fatty acid blend. Component A as primary collector can also comprise fatty acid ester or fatty acid peptides. Component A can influence the hydrophobicity of foams in froth flotation for beneficiation of phosphates from phosphate containing ores. Component A in particular acts as primary collector in froth flotation processes.

It was found that alcohol alkoxylates, as secondary collector, containing linear or branched alcohol moieties are significantly more suitable to achieve high selectivity in froth flotation for beneficiation of phosphates when used as surfactant in combination with particularly unsaturated fatty acids in trans configuration. This can be achieved by using the alcohol alkoxylates (non-ionic surfactants) alone or as a blend with sulfonate emulsifiers. It is espe cially pronounced when ethoxylated and propoxylated oxo-alcohols are used as surfactant respectively as main components of surfactant (> 10% of the surfactant by weight, respec tively > 2% of the overall collector composition by weight). The use of such blends allows a significant increase in flotation selectivity, allowing concentrates with more than 30wt% P ₂ 0 ₅ for example 31-33wt% P ₂ 0 ₅ to be achieved without additional loss of apatite into the flotation slurry compared to the state of the art.

A further advantage of the present invention is that for example the use of a combination of two different components A and B in reverse phosphate flotation makes phosphate contain ing sedimentary ores accessible to phosphate beneficiation processes. Furthermore, it is an advantage that a ternary collector composition comprising at least the components A, B and C can efficiently be used for direct and/or reverse flotation of phosphate containing ores in order to increase the flotation selectivity and/or recovery. In particular surprising was that a combination of two different non-ionic surfactants as collectors (components B and C) in combination with unsaturated trans fatty acids (component A) in reverse phosphate flota tion leads to improved grades of P ₂ 0 ₅ . The combination of non-ionic surfactants (compo nents B and C) and unsaturated trans fatty acids (component A) as collector blend / collec tor composition is suitable for direct and/or reverse flotation and improves the flotation per formance with regard to improved grades and/or recoveries of P ₂ 0 ₅ . Preferred is also the use of a combination of two non-ionic surfactants (components B and C) for the flotation of igneous and/or sedimentary phosphate ores, which leads to improved grades of P ₂ 0 ₅ .

It is in particular preferred that the collector composition of the present invention is used in form of a“ready to use” composition, which means that a mixture of the component A, com ponent B and optionally component C can be prepared and optionally stored, before the col lector composition is used in a flotation process. Such mixture can be named“pre-mixture” and can act for example as self-emulsifying composition when the collector composition (pre-mixture) is added to an ore-slurry before start of the flotation. Further preferred is also that the individual components A, B and optionally C are added separately to an ore-slurry before flotation starts.

It is preferred, that the component B (secondary collector) in particular comprises non-ionic surfactants. It is preferred that component B is for example a linear or branched alkoxylated alcohol. Ethoxylated and/or propoxylated isotridecanol grades are preferred as component B. In particular, the component B can be used as secondary collector in froth flotation of non-sulfidic ores, in particular phosphoric ores.

It is preferred, that the optional component C is in particular a non-ionic surfactant or an anionic surfactant or a mixture thereof. It is further preferred that component C is a blend of non-ionic surfactants or of anionic surfactants or a mixture thereof. In particular, the com ponent C can act as secondary and/or ternary collector in froth flotation of non-sulfidic ores, in particular phosphoric ore. Preferably, component C comprises sulfonated fatty ac ids, dialkyl sulfosuccinates, di- or tetraalkyl sulfosuccinamates, sodium dodecyl sulfate, al kyl ether sulfates, alkyl benzenesulfonates, di(2-ethylhexyl)sulfosuccinate. Dioctyl sulfosuc- cinate is a preferred component C. Also preferred as component C, are for example sul fonates or sulfates like dodecylbenzene sulfonic acid or salts thereof, sodium lauryl sulfate, sodium laureth sulfate, sodium coco sulfate, alkyl sulfates, alkyl sulfonates, petroleum sul fonates. It is further preferred that component C is a linear or branched alkoxylated alcohol. Ethox- ylated isotridecanol grades are preferred as component C, wherein the ethoxylated isotride- canol grade of component C is in particular different to the ethoxylated isotridecanol grade of component B. In particular, the collector composition of the present invention comprises at least two different alkoxylated isotridecanol grades. Preferably the difference between component B and component C is in the degree of alkoxylation. Further preferred is that component B and component C have different HLB values. The average number of alkoxy groups arises from the sum of all alkoxy groups of the individual molecules divided by the number of individual molecules. In particular,“degree of alkoxylation" means the average molar ratio between the molecule which gets alkoxylated (reaction with oxiran or al- kyloxirans), and the selected respective (alkyl)oxirans.

Preferably, the collector composition according to the present invention comprises a com ponent B which comprises the alkoxylation product of linear or branched alcohols, where the alcohols have 9 to 18, preferably 10 to 17, more preferably 11 to 15 and most preferably 12 to 14 carbon atoms. It is in particular preferred that the alkoxylated alcohols have 13 car bon atoms. The component B of the collector composition can comprise only one of such alcohols, but in particular comprises a mixture of such alcohols.

Preferably, the collector composition according to the present invention comprises a com ponent C which comprises the alkoxylation product of linear or branched alcohols, where the alcohols have 6 to 20, preferably 8 to 18, more preferably 10 to 16 and most preferably 12 to 14 carbon atoms. It is in particular preferred that the alkoxylated alcohols have 13 car bon atoms. The component C of the collector composition can comprise only one of such alcohols, but in particular comprises a mixture of such alcohols.

Preferably, the degree of alkoxylation of the alcohols for the component B in the collector composition according to the present invention assumes, on average, values in the range from 0.1 to 15, preferably from 1 to 12, more preferably from 1 to 10, even more preferred from 2 to 7 and most preferably from 3 to 5. As degree of alkoxylation of the alcohols for the component B any value between these values or ranges thereof are also preferred. It is in particular preferred that the degree of alkoxylation of the alcohols for the component B is about 3, 4, 5, 6, 7, 8, 9 or 10.

It is preferred, that the component B in particular comprises non-ionic surfactants, which are alkoxylated linear or branched alcohols which comprise in particular two different types of alkoxy groups / moieties. Preferably, the linear or branched alkoxylated alcohols com prise ethoxylated and propoxylated moieties. Isotridecanol grades are preferred as alcohol moiety of component B. In particular, the component B can be used as secondary collector in froth flotation of non-sulfidic ores, in particular phosphoric ores. Further preferred is that the component B is in particular a non-ionic surfactant or a mixture thereof. It is further preferred that component B is a blend of non-ionic surfactants. Component B for example can be described as at least one adduct of two different types of alkoxy moieties with a C ₈ to C ₂₂ fatty alcohol. Preferably, component B is an adduct of ethylene oxide and propylene oxide with a C ₈ to C ₂₂ fatty alcohol. Further preferred is that the two different types of alkoxy moieties are selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, pentylene oxide, hexylene oxide, heptylene oxide, octylene oxide, nonylene oxide or decylene oxide.

In particular, component B is an alkoxylated alcohol of the formula

R'-CMCH,- CH(R ² )-0) _k -(CH ₂ - CH(R ³ )-0),-(CH ₂ - CH (R ⁴ )-0) _m -R ⁵ , wherein

R ¹ : is a linear or branched alkyl group having 9 to 18 carbon atoms,

R ² : is independently hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms,

R ³ : is independently hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms,

R ⁴ : is independently hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms,

R ⁵ : is H or methyl

k: is an integer of 1 to 10,

I: is an integer of 1 to 10,

m: is an integer of 1 to 10, and

wherein R ² and R ³ or R ³ and R ⁴ are different.

Preferably, the degree of alkoxylation of the alcohols for the component C in the collector composition according to the present invention assumes, on average, values in the range from 1 to 30, preferably from 2 to 25, more preferably from 4 to 20 and most preferably from 6 to 15. It is in particular preferred that the degree of alkoxylation of the alcohols for the component C is about 7, 8, 9, 10, 11, 12, 13, 14 or any value between these values or ranges thereof.

It is further preferred that the difference in degree of alkoxylation between component B and C in the collector composition according to the present invention assumes, on average, values in the range from 1 to 20, preferably from 1 to 16, more preferably from 2 to 14 and most preferably from 3 to 12. It is in particular preferred that the difference in degree of alkoxylation between component B and C is in the range from 4 to 10.

Preferably, the alkoxy groups are C ₂ -C ₁₀ -alkoxy groups, for example ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy and decoxy groups. However, preference is given to ethoxy, propoxy, butoxy, and pentoxy. Ethoxy, propoxy and butoxy groups are more pre ferred. More preferred still are ethoxy and propoxy groups. Particular preference is given to ethoxy groups. It is possible for the alkoxylation to take place in random distribution or blockwise, meaning that the aforementioned alkoxy groups - whether these are different - occur blockwise.

It is preferred if the alcohol mixture of component B has an average degree of branching from 0 to 5, preferably from 1.5 to 4.5, more preferably from 2 to 4 and most preferably from 2.5 to 3.5. It is in particular preferred that the degree of branching is about 3. It is preferred if the alcohol mixture of component C has an average degree of branching from 0 to 5, preferably from 1.5 to 4.5, more preferably from 2 to 4 and most preferably from 2.5 to 3.5. It is in particular preferred that the degree of branching is about 3.

Furthermore, the collector composition can have alkoxylation products, in which case alco hols do not have the number of carbon atoms stated above from these products. These are in particular alcohols having 1 to 7 carbon atoms, and also alcohols with more than 12 car bon atoms. However, it is preferred if this group of compounds has a weight fraction of at most 10% by weight, preferably of less than 5% by weight, based on the total weight of the collector composition.

If two or more alcohols are used for the component B and/or component C, in the event that the alcohol has 10 carbon atoms, it is preferred that this mixture is a CIO Guerbet alcohol mixture. Here, the main components are 2-propylheptanol and 5 methyl-2-propylhexanol. Preferably, the component B and/or component C consists to at least 90%, preferably 95%, of such mixture.

Further preferred is that during the flotation process a modifier is added in addition to the collector composition of the present invention. Such modifier can be for example a pH-mod- ifier. PH-modifier comprise for example lime, soda ash, caustic soda, sulfuric acid, hydro chloric acid, phosphoric acid. It is further preferred that for example depressants, activators and/or frothers are used during the flotation process for conditioning the ores as far as nec essary.

Preferably, the amount of component A in weight-% (wt%) in relation to the total collector composition is in the range from 50 wt% to 99.9 wt%, preferably in the range from 55 wt% to 85 wt%, more preferably in the range from 60 wt% to 80 wt% and most preferably in the range from 65 wt% to 75 wt%. It is in particular preferred that the amount of component A in weight-% in relation to the total collector composition is about 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt% or any value between these values or ranges thereof.

Preferably, the amount of component B in weight-% (wt%) in relation to the total collector composition is in the range from 0.1 wt% to 50 wt%, preferably in the range from 1 wt% to 40 wt%, more preferably in the range from 5 wt% to 35 wt% and most preferably in the range from 10 wt% to 30 wt%. It is in particular preferred that the amount of component B in weight-% in relation to the total collector composition is about 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt% or any value between these values or ranges thereof.

Preferably, the amount of component C in weight-% (wt%) in relation to the total collector composition is in the range from 0 wt% to 40 wt%, preferably in the range from 0.5 wt% to 35 wt%, more preferably in the range from 1 wt% to 30 wt% and most preferably in the range from 1.5 wt% to 25 wt%. It is in particular preferred that the amount of component C in weight-% in relation to the total collector composition is about 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt% or any value be tween these values or ranges thereof.

Preferably, the amount of further additives and/or modifier is in the range from 0% to 10%, preferably in the range from 0.2% to 8%, more preferably in the range from 0.4% to 6% and most preferably in the range from 0.5% to 5%.

In a further aspect the invention relates to a flotation process for beneficiation of phosphate from phosphate containing ores comprising the collector composition of the present inven tion. As pretreatment of the ores before direct flotation and/or reverse flotation the ores may be crushed or ground to finer particles. For the froth flotation then the targeted min eral, in particular phosphates in case of direct flotation and in particular carbonates and/or silicates or other impurities in case of reverse flotation, is rendered hydrophobic by addition of the collector composition. The targeted minerals can either be collected in the froth (di rect flotation) or remain in the slurry as cell product (reverse flotation). Flotation can be un dertaken in several stages / cycles to maximize the recovery of the desired mineral and to maximize the concentration of the desired mineral. Surprisingly, by addition of the collector composition of the present invention the number of stages / cycles can be reduce while achieving the same grade as with more stages / cycles.

It must be noted that as used herein, the singular forms“a”,“an”, and“the”, include plural references unless the context clearly indicates otherwise. Thus, for example, reference to“a reagent” includes one or more of such different reagents and reference to“the method” in cludes reference to equivalent steps and methods know to those of ordinary skill in the art that could be modified or substituted for the methods described herein.

Unless otherwise indicated, the term“at least” preceding a series of elements is to be un derstood to refer to every element in the series. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the spe cific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the present invention.

The term“and/or” wherever used herein includes the meaning of “and”,“or” and“all or any other combination of the elements connected by said term”.

The term“about” or“approximately” as used herein means within 20%, preferable within 10%, and more preferably within 5% of a given value or range. The term“about” or“approxi mately” as used herein also includes the exact respective values or ranges.

Throughout the specification and the claims which follow, unless the context requires oth erwise, the word“comprise”, and variations such as“comprises” and“comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term“comprising” can be substituted with the term“containing” or“including” or sometimes when used herein with the term“having”.

When used herein“consisting of” excludes any element, step, or ingredient not specified in the claim element. When used herein,“consisting essentially of” does not exclude material or steps that do not materially affect the basic and novel characteristics of the claim.

Although the invention has been described with respect to specific embodiments and exam ples, it should be appreciated that other embodiments utilizing the concept of the present invention are possible without departing from the scope of the invention. The present inven tion is defined by the claimed elements, and any and all modifications, variations, or equiva lents that fall within the true spirit and scope of the underlying principles.

EXAMPLES

The invention is further described by the following examples. The examples relate to practi cal and in some cases preferred embodiments of the invention that do not limit the scope of the invention.

Example 1

Reverse flotation (collection of carbonate impurities in the froth)

Methodology

The flotation experiments were performed in a 1.5 L plexiglass flotation cell in a Denver D12 flotation machine. A carbonaceous phosphate ore with ~ 60% apatite and ~ 30% calcite was subjected to grinding and desliming at 0.071 mm. A homogeneous 240 g sample of the ore was prepared. 1.2 L water at pH 5 (pre-prepared acidified tap water of Ludwigshafen, Ger many, or recovered process water from a previous test) has been placed in the cell. The ro tor was turned on at 900 rpm and the ore sample was added to the cell with a closed air supply. The slurry was subsequently conditioned per the following scheme:

Phosphoric acid 10% (3.6 mL) -> 30 s

Sulfuric acid 20% (2.4 mL) -> 30 s

Collector (neat), 500 g/t -> 60 s

Additional small amounts of sulfuric acid were added during the test constantly to maintain pH in the narrow range of 4.9-5.2. After the last conditioning step, the flotation was per formed at 300 L/h air throughput for 2.5 min. After this period the air supply was turned off. Both fractions (froth product and cell product) were dewatered by vacuum filtration (pro cess water recovered for the next water recycling stage if necessary), dried at 90° C for 2 h, homogenized thoroughly and analyzed for phosphate content (P ₂ 0 ₅ content). The experi ments have been repeated 6x each with process water recovery and re-use. The %-values for the amounts of primary and secondary collector in table 1 are weight-%.

Table 1

From table 1 it becomes obvious that with the collector composition which comprises un saturated fatty acids in trans configuration the grade of P ₂ 0 ₅ can be increased to values about 33 wt%. This is unexpected in comparison to the collector composition which com prises only fatty acids in cis configuration. Under shown conditions, the collector composi tions show preference for carbonate so that carbonate is floated and apatite remains in the cell. Furthermore, it can be observed that a ternary collector composition with in particular unsaturated fatty acids in trans configuration offer a synergistic effect with regard to P ₂ 0 ₅ grade, which is desirous for subsequent processing to e.g. fertilizer. The primary collector comprising unsaturated fatty acids only in cis configuration is oleic acid (CAS-No. 112-80-1) from vegetable source. The oleic acid may have a varying content of C ₁₆ , C ₁₈ saturated fatty acids. The primary collector comprising unsaturated fatty acids in trans configuration is from animal source (CAS-No. 67701-08-0) e.g. tallow. The tallow may have a varying con tent of elaidic acid as well as varying amounts of C ₁₆ , C ₁₈ saturated fatty acids. The second ary collector comprises alkoxylated isotridecanol, in particular, an ethoxylated and propox- ylated isotridecanol grade / mixture (CAS-No. 196823-11-7) with a degree of ethoxylation of about 6-7 and with a degree of propoxylation of about 3-4. The secondary collector in par ticular comprises dioctyl sulfosuccinate (CAS-No. 577-11-7) as further secondary collector. As shown, the present invention offers an unexpected advantage with regard to grade val ues of P ₂ 0 ₅ . With the ternary collector composition, surprisingly, phosphate containing ores which so far where not accessible for phosphate beneficiation / phosphate enrichments can now be processed using for example collector compositions of the present invention for froth flotation.