The present invention relates to a process to treat siliceous non-sulfidic ores, such as siliceous phosphate ores, and to collector compositions that are suitably used in such processes.

Froth flotation is a physico-chemical process used to separate mineral particles considered economically valuable from those considered waste. It is based on the ability of air bubbles to attach onto those particles previously rendered hydrophobic. The particle-bubble combinations then rise to the froth phase from where it discharges the flotation cell whilst the hydrophilic particles remain in the flotation cell. Particle hydrophobicity is, in turn, induced by special chemicals called collectors. In direct flotation systems, it is the economically valuable minerals which are rendered hydrophobic by the action of the collector. Similarly, in reverse flotation systems, the collector renders hydrophobicity to those mineral particles considered waste. The efficiency of the separation process is quantified in terms of recovery and grade. Recovery refers to the percentage of valuable product contained in the ore that is removed into the concentrate stream after flotation. Grade refers to the percentage of the economically valuable product in the concentrate after flotation. A higher value of recovery or grade indicates a more advantageous flotation system. Usually for a collector to be of commercial interest in an application a minimum grade needs to be reached and for this minimum grade an as high as possible recovery. In collector compositions usually the secondary collector is primarily responsible for improvement of the recovery, efficiency, frothing characteristics, etc and the primary collector for the selectivity.

DE 4016792 discloses, like DE 4010279 and DE 4133063, a process to treat siliceous non-sulfidic ores by a flotation process. In DE 792 as collector composition mixtures of esters of dicarboxylic acid with fatty acid monoalkylamides are used, optionally in combination with further anionic or non-ionic surfactants. In DE 279 as collector composition dicarboxylic acid N alkylmonoamides are used, optionally in combination with further anionic or non-ionic surfactants. In DE Ό63 etheramines with at least one anionic or non- ionic co-collector component are used as collector composition. Following formulae XVII and XVIII in DE'792 alkylphosphates and alkyletherphosphates are one option (out of many) of compounds that can be employed as such (optional or secondary) collector component. The use of phosphate compounds as a primary collector is not disclosed or suggested in any of the documents. Neither is in any of the Examples the use of a pyrophosphate component in a collector composition demonstrated, nor is it disclosed or suggested that di- or higher alkylated phosphates lead to a benefit in a flotation process.

EP 544185 discloses a process to treat non-sulfidic siliceous ores by using a collector composition that contains as a primary collector a sulfosuccinate and optionally a further surfactant that may be chosen from a big group of possibilities and that also includes an alkyl phosphate or alkyletherphosphate. The use of phosphate compounds as a primary collector is not disclosed or suggested in EP 544185. EP 544185 furthermore does not disclose alkyldiphosphate, alkyltriphosphate or alkyltetraphosphate compounds. In none of the Examples of EP 544185 the use of a phosphate in a collector composition is demonstrated, nor is the difference between different phosphate compounds suggested.

GB 1093504 discloses a process to treat a siliceous ore by using a phosphorous atom-containing compound of the formula RaHbPcOd wherein c can be 1 or 2. The phosphate compounds can be alkylated and preferably are hypophosphates. Pyrophosphates are also suggested but not actually tested. The process to treat the ores is aimed at separating off several minerals of value from the ores. The flotation process of GB 504 wherein phosphate is the mineral of value, Example 1 1 , is a flotation process at preferably a low pH, wherein the phosphate is collected in the froth. The phosphate compound in this Example is a lauryl alcohol based hypophosphate and the results of the flotation process are - with P2O5 assay of 28% - subject to improvement

The invention now provides a process to treat siliceous non-sulfidic ores with a collector composition that comprises a phosphate compound of the formula I

wherein R is linear or branched, saturated or unsaturated hydrocarbon group containing 1 to 24 carbon atoms, A is an alkylene oxide unit; Y is H, Na, K or an ammonium or alkylated ammonium, n is 1 - 3, p is 0 - 25, X is chosen from the same groups as R-Ap or Y.

In this document the compounds of formula I wherein n is 1 -3 are also sometimes referred to as "pyrophosphates" so to distinguish them from "monophosphates" wherein n is 0.

The invention furthermore relates to a collector composition for the process to treat siliceous non-sulfidic ores wherein the collector composition comprises the above phosphate compound of the formula I as a primary collector, and a secondary collector that comprises a monophosphate compound and one or more other secondary collector compounds that can be an anionic collector compound selected from the group of fatty acids, alkylsulfosuccinates, alkylmaleates, alkylamidocarboxylat.es, esters of alkylamidocarboxylat.es, alkylbenzensulphonat.es, alkylsulfonates, sulphonated fatty acids or a nonionic collector compound of the group of ethoxylates, glycosides, ethanolamides or a mixture of two or more of these anionic and nonionic collectors. The present invention provides an improved process to treat siliceous ores and collector compositions for use therein which provide the required grade of separation of the desired product from the ore and an improved recovery and selectivity. The present invention additionally provides an improvement in that a reduced total amount of the collector composition can be employed in the flotation process.

It should be noted that US 4,287,053 discloses a phosphate depressant for treating siliceous phosphate ores. Depressants however are known to have a distinctly different function than collectors. Also US 2,424,552 discloses phosphates as a depressant, which are in this document all inorganic phosphates. In the examples hexametaphosphate is used. The document does not disclose organic phosphates, such as phosphates containing a hydrocarbon group.

When R is a group containing 1 to 12 carbon atoms, the DB is preferably between 0 and 2.2 and p is higher than 0. When R contains 1 to 12 carbon atoms preferably at least one unit A is present which is a propylene oxide unit. Even more preferably when R contains 1 to 10 carbon atoms, p is between 1 and 25, yet more preferable between 4 and 10 and most preferable between 5 and 8. When R contains 1 to 10 carbon atoms, even more preferably one or more of the A units are propylene oxide or butylene oxide, or when R contains 1 to 10 carbon atoms in another more preferable embodiment a block of propylene oxide units A is first bound to R and next a block of ethylene oxide units A.

If R is a group containing 12 to 16 carbon atoms, p is preferably higher than 0, and in a further preferred embodiment the groups A are propylene oxide, ethylene oxide or a combination of both propylene oxide and ethylene oxide. When R contains 12 - 16 carbon atoms it is preferably branched. Even more preferably, the degree of branching is between 0.2 and 3. When R contains more than 16 carbon atoms it is preferably linear and unsaturated. More preferably when p is higher than 0, and R contains more than 16 carbon atoms, one or more of the groups A are ethylene oxide. Yet even more preferably when R contains more than 16 carbon atoms the degree of unsaturation is between 0.2 - 2, most preferably 0.5 - 1 .1 .

If the alkoxylation degree (DA, the value of p) is 0 then preferably, R is a group containing 8 to 16 carbon atoms, even more preferably R is a group containing 9 to 15 carbon atoms. In another preferred embodiment R is a saturated hydrocarbon group. When R has up to and including 12 carbon atoms it is preferably linear or branched to a limited degree. When R contains more than 12 carbon atoms it is preferably branched. Even more preferably when R contains up to and including 12 carbon atoms the degree of branching is 0-2.2 and when R contains more than 12 carbon atoms the degree of branching is preferably between 1 .5 and 3.

In another preferred embodiment each A is independently a propylene oxide group or ethylene oxide group. Even more preferred A is an ethylene oxide group. The value of p is preferably 0-15, more preferably 1 -10, most preferably 2-8. If R contains more than 12 carbon atoms, the value of p is preferably chosen higher than when R contains up to and including 12 carbon atoms.

By the degree of alkoxylation (DA) as used herein is meant the total number of alkylene oxide units A between the alkyl chain R and phosphorous containing unit, which corresponds with the value of p in formula I. As understood by someone skilled in the art, a degree of alkoxylation is an average number and does not have to be an integer. The alkylene oxide units A are suitably ethylene oxide, propylene oxide or butylene oxide. By "the degree of unsaturation" (DU) as used herein is meant the total number of double bonds in the alkyl chain. It should be noted that degree of unsaturation is an average value for the R groups as present in the phosphate compound of formula I or formula II and hence does not have to be an integer.

By "the degree of branching" (DB) as used herein is meant the total number of (terminal) methyl groups present on the R alkyl chain minus one (side chains that are alkyls other than methyls being counted by their terminal methyls). It should be noted that degree of branching is an average value for the R groups as present in the phosphate compound of formula I and hence does not have to be an integer.

In yet another preferred embodiment n=1 .

In an embodiment, the process of the invention relates to the separation of apatite from non-sulfidic siliceous ores.

Siliceous ores are ores that contain silicas (SiO2). In preferred embodiments the siliceous ores contain between 5 and 80 wt% of silica. Even more preferred siliceous ores contain between 20 and 75% by weight of silica. The amount of phosphate minerals such as apatite in the siliceous ore in embodiments is between 8 and 40% by weight, preferably 10-30 wt%. In further embodiments the ores may contain other main minerals such as iron oxide minerals, further defined below. In an embodiment the process is a process for selective flotation of apatite.

In a preferred embodiment the process is a direct flotation, even more preferred it is a direct flotation process to isolate the phosphate minerals from the siliceous ores.

The pH during the process of the present invention is preferably between 8 and 1 1 . The collector composition of the present invention for use in a process to treat non-sulfidic siliceous ores contains a primary collector that comprises a phosphate of the above formula (I) wherein R, X, Y, A, p and n have the same meaning as above, a monophosphate secondary collector compound that is preferably of the formula II

and one or more other secondary collectors that may be an anionic collector selected from the group of fatty acids that are preferably of the formula RCOOY, sulphonated fatty acids that are preferably of the formula RCH(SO3Y)COOY, alkylsulfosuccinates that are preferably of the formula III

alkylmaleates that are preferably of the formula IV

alk lamidocarboxylat.es that are preferably of the formula V

V wherein in all above structures and formulae ll-V, each R, A, p, Y independently has the meaning as defined above for formula I, m is 0-7 , B is -H, -CH ₃ , - CH(CH ₃ ) ₂ , -CH ₂ CH(CH ₃ ) ₂ , -CH(CH3)CH ₂ CH _3j Z is -H, -CH ₃ or -CH ₂ CH ₃ , esters of the above alkylamidocarboxylat.es (following the formula V of the alkylamidocarboxylat.es compounds wherein Y is an alcohol derived hydrocarbon group, such as also described in US20160129456),

alkylbenzensulphonat.es that are preferably of the formula VI

alkylsulphonates that are preferably of the formula VII

VII

or a nonionic collector of the group of alkoxylates (alkoxylated fatty alcohols RO(A)H, alkoxylated fatty acids RC(O)O(A)H), alkyl glycosides R(C ₆ O ₆ Hn) _k , alkylethanolamides of the formulae VIII or IX

IX wherein each R, A and Z independently have the above-indicated meaning, f is 1 -25, preferably f is 1 -15, and most preferable 1 -10 k is 1 -5, preferably k is 1 -2, and each f is independently 1 to 25;

or a mixture of two or more of these anionic and nonionic collectors.

The monophosphate secondary collector compound can be separately and purposively added to the collector composition and can be chosen from the group of compounds as defined above with formula II but monophosphate compounds can be inherently formed in the process to prepare the primary collector phosphate compound of above formula I. If in the composition obtained when manufacturing the phosphate compound of formula I such other phosphates are not removed, a composition is obtained that inherently contains both a primary collector of the present invention and a monophosphate secondary collector.

Preferably, the primary collector is present in an amount of 5-60 wt %, more preferably 10-60 wt%, the monophosphate secondary collector in an amount of 5-75 wt%, more preferably 10-75 wt%, and any other secondary collector in an amount of 1 - 50 wt%, wherein the wt% is the wt% on total solids content of the collector composition.

In preferred embodiments the amount of monophosphate secondary collector is between 25 and 75 wt%, more preferably 30 and 65 wt%, on total solids content of the collector composition because monophosphates as explained above are often formed in processes to prepare di- and tri and tetraphosphates and for the purpose of using the higher phosphates in a collector composition it is not needed to separate off the monophosphates, as they can play a role as a secondary collector. Other secondary collectors are preferably present in an amount of 5- 50 wt%. The amount of the phosphate compound of formula I in the collector compositions and process of the present invention is preferably between 5 and 50wt% In another preferred embodiment the amount of the phosphate compound of formula I in the collector compositions and process of the present invention is between 5 and 45 wt% , even more preferred between 10 and 40 wt%, most preferred between 15 and 35 wt% on total phosphate. The collector composition can be added to the flotation in concentrated form (i.e. 5 -100 wt% solids, preferably 50 - 100wt% solids) or as 1 -5 weight % aqueous solution.

The process and collector composition of the invention may involve other additives and auxiliary materials which are typically present in a froth flotation process that can be added at the same time or, preferably, separately during the process. Further additives that may be present in the flotation process are depressants (such as starch, dextrin, quebracho), dispersants (such as water glass), frothers/froth regulators/froth modifiers/defoamers (such as MIBC, Texanol, alkoxylated low molecular weight alcohols), and pH-regulators (such as NaOH).

In another aspect, the present invention relates to a pulp comprising crushed and ground ore, a primary collector or a collector composition as defined herein, and optionally further flotation aids. This pulp can be prepared by first grounding the ore and then adding collector composition or by adding at least part of the collector composition to the ore and milling the ore to pulp in the presence of at least part of the collector composition.

The siliceous ores that can be used in the process of the invention may include further minerals than silicas and phosphates. The mineral composition of most of the siliceous ore deposits throughout the world is generally similar, differing only in percentage of each mineral present according to their origin. Further minerals present in the siliceous ores may be gneisses, granites and pegmatites and there may be mentioned in particular-ilmenite, rutile, monazite, zircon, silljmanite, kyanite, andalusite, garnet, spinel, corundum, staurolite, tourmaline and epidote. The amount of the collector used in the process of reversed flotation of the present invention will depend on the amount of impurities present in the ore and on the desired separation effect, but in some embodiments will be in the range of from 10-1000 g/ton dry ore, preferably in the range of from 20-500 g/ton dry ore, more preferably 25-200 g/ton dry ore.

The present invention is illustrated by below examples Example 1A

Synthesis of alkyl ethoxylated pyro-phosphate

Oleyl alcohol (60.0 g) ethoxylated with 4 equivalents of EO was added to a glass reactor with a flange equipped with an overhead stirrer. The reactor was flushed with nitrogen for 10 minutes. The mixture was heated with an oil bath to 55°C and methylsulfonic acid (3.69 g) was added. Phosphorus pentoxide (9.71 g) was added portion wise, keeping temperature at 55°C. Stirring at 55°C under nitrogen atmosphere was continued overnight. The final product was analyzed by ³¹ P-NMR spectroscopy. ³¹ P -NMR (CDCI ₃ ): 5 4 - -1 ppm alkylated monophosphate; δ -12 - -16ppm alkylated pyro-phosphate; δ -28 - -30ppm inorganic phosphates.

Example 1 B

Synthesis of alkylated pyro-phosphate

Isotridecanol (40 g, 200 mmol) was added to a glass reactor with a flange equipped with an overhead stirrer. The reactor was flushed with nitrogen for 15 minutes. The mixture was heated with an oil bath to 55°C and methylsulfonic acid (5.39 g, 5.39 mmol) was added. Phosphorus pentoxide (14.2 g, 100.0 mmol) was added portion wise, keeping temperature at 55°C. Stirring at 55°C under nitrogen atmosphere was continued overnight. The final product was analyzed by ³¹ P-NMR spectroscopy. ³¹ P -NMR (CDCI ₃ ): δ 4 to -1 ppm monophosphate; δ -12 to -16 ppm pyro-phosphate; δ -28 to -30 ppm polyphosphate.

Example 2 General flotation procedure

Five hundred (500) g of the phosphate ore containing 25% of apatite, and 70% of different silica minerals was placed into a 1 .4L Denver flotation cell, water was added to the marked level and the mixing started. Then 1 minute conditioning with 10.0 ml of a 1 %(w/w) aqueous starch solution was performed, keeping the pH of the flotation mixture at 9.9 with a 5% NaOH aqueous solution. Then the collector ^* was added as a 1 %(w/w) solution, and conditioning was continued for 2 minutes, keeping the pH of the flotation mixture at 9.9 with a 5% NaOH aqueous solution. The flotation was performed at RT (20±1 °C) and air supplied at 3.5 l/min speed. The rougher flotation, followed by two cleaning steps (1 .0L Denver cells), was performed. All fractions (tailings, middlings and concentrate) were collected and analyzed. Figure 1 illustrates the flotation steps performed and the different fractions collected.

The following two collector compositions were compared:

^* collector composition 1 : 67 wt% oleic fatty acid, 23 wt% monophosphate of oleyl ethoxylate(4EO), 10 wt% pyrophosphate of oleyl alcohol ethoxylate(4EO) as prepared in Example 1A- invention

^* collector composition 2: 67 wt% oleic fatty acid, 33 wt% monophosphate of oleyl ethoxylate(4EO) prepared by reacting the ethoxylated oleyl alcohol as employed in Example 1 A with polyphosphoric acid - comparison Number of cleaning steps is depending on how much solid material there are in the froth products. Flotation goes on till there are no more particles in the froth. Time above indicate how long that takes. The collectors displayed in Table 1 were used in the flotation procedure above, and the flotation results with these collectors are displayed in Table 1 . The selectivity factor is calculated according to the following equation:

„ , . . _r reduction of waste (%)

Selectivity factor = lOO-recovery of apatite (%)'

Where waste in fraction (%)

Reduction of waste (%) = — -— , * 100

waste in the feed {%)

The selectivity factor should be as high as possible.

Table 1. Flotation results presented as P205 recovery and grade

Phosphate Dosage, Fraction Amount of phosphate Selectivity collector g/t as P2O5 factor component

Grade % recovery %

Invention 130 Rougher 96.6 1 .8

Collector 1

concentrate

(oleyl

alcohol+4EO 1 cleaner 94.6 0.7 mono- and

concentrate

pyrophosphate

mix) 2 ^nd cleaner 39.00 91 .8 0.3

concentrate

Comparison Rougher 96.4 2.0

Collector 2

concentrate

Oleyl

alcohol+4EO 1 cleaner 93.5 0.6 only

concentrate

monophosphate)

2 ^nd cleaner 39.50 87.8 0.2 concentrate From the results presented in the table 1 one can see that the use of alkoxylated alkyl pyro-phosphate allows obtaining high quality apatite concentrate (grade = 39%) at higher than 90% recovery using around 12% less of total collector mixture, while using only monophosphate gives less good results.

Example 3

Example 2 was repeated but the following two collector compositions were compared (see for dosage below Table 2)

^* collector composition 3: 60 wt% of isotridecyl pyrophosphate (n=1 -3) and 40 wt% of isotridecyl monophosphate (n=0) as prepared in Example 1 B- invention ^* collector composition 4: 100% isotridecylmonophosphate (n=0) prepared by reacting isotridecanol with polyhosphoric acid - comparison

The results are summarized in below Table 2. Table 2. Flotation results presented as P205 recovery and grade

Collector Dosage, Fraction Amount of phosphate as P ₂ 0 ₅

g/t

Grade % recovery %

Invention 100 Rougher

Collector 3

concentrate

(mix of 60% 32.07 91.8

Isotridecyl 1 ^st cleaner

pyrophosphate,

40% isotridecyl concentrate

38.33 86.1

monophosphate) 2 ^nd cleaner

concentrate

39.69 80.3 Comparison 100 Rougher

Collector 4

concentrate

(100% 25.83 35.1

isotridecyl 1 cleaner

monophosphate)

concentrate

35.15 23.2

2 ^nd cleaner

concentrate

38.25 18.4

This Example demonstrates that using a monophosphate alone results in very weak collecting properties in siliceous ores.