MXPA97008860A - Method for depression of ganga minerals desilicato without sulf - Google Patents

Abstract

The present invention describes a method for the depression or sedimentation of non-sulphided silicate filler or silicate gangue minerals, wherein the depressant is a polyvinyl alcohol graft polymer of an acrylamide or a mixture thereof with a polysaccharide.

Description

METHOD FOR DEPRESSION OF SULFIDE-FREE SILICATE GAS MORTARS BACKGROUND OF THE INVENTION The present invention relates to foam flotation processes for the recovery of valuable sulfide ores from basic metal sulfide ores. More particularly, this relates to a method for the depression of non-sulphided silicate gangue minerals in the benefit of valuable sulfide minerals by foam flotation processes. Some theory and practice states that the success of a sulfide flotation process depends to a greater degree on reagents called collectors that impart selective hydrophobicity to the valuable mineral, which has to be separated from other minerals. Other important reagents, such as modifiers, are also responsible for the successful flotation separation of valuable sulfur and other minerals. Modifiers include, but are not necessarily limited to, all reagents whose main function is neither to collect REF: 25892 nor to float by foam, but usually to modify the surface of the mineral, so that it does not float. In addition to attempts to manufacture more selective sulphide harvesters for valuable sulfide ores, other procedures to improve the flotation separation of valuable sulfide ores have included the use of modifiers, more particularly depressors, to knock down the non-sulphided gangue minerals, so that these can not float together with the sulfides, thereby reducing the levels of non-sulphided gangue minerals with respect to the concentrates. A depressant (chemical product used in flotation process by foam) is a modifying reagent which acts selectively on certain unwanted minerals and prevents or inhibits its flotation. In the flotation of valuable sulfide ore, certain unsulfurized silicate gangue minerals present a unique problem as they show natural buoyancy, for example they float independently of the collectors of valuable sulfide ore used. Even if very valuable selective sulfide ore collectors are used, these silicate minerals affect the sulfide concentrates. Talc and pyrophyllite, both belong to the class of magnesium silicates, and are particularly problematic in that they are naturally highly hydrophobic. Other magnesium silicate minerals that belong to the classes of olivins, pyroxenes, and serpentine show varying degrees of flotation capacity, which seems to vary from one mineral deposit to another. The presence of these unwanted minerals in the concentrates of valuable sulfide ore causes many problems, for example a) they increase the mass of the concentrates, adding in this way to the cost of handling and transportation of the concentrate, b) it competes with the space in the foam phase during the flotation stage, thereby reducing the total recovery of valuable sulfide ore, and c) diluting the sulfide concentrate with respect to the valuable content of sulfide material, which makes them less suitable, and some inappropriate cases, for the fusion of the same, because they interfere with the merger operation. The commonly used depressants in the sulfide flotation include materials such as inorganic salts (NaCN, NaHS, S02, sodium metabisulfite, etc.), and small amounts of organic compounds such as sodium thioglycolate, mercaptoethanol, etc. It is known that these depressants are capable of lowering or lowering sulphide minerals, but they are not known to be depressants for unsulfurized minerals, just as known valuable sulfide collectors, they usually are not good collectors of valuable, non-sulfided minerals. Sulfur and non-sulfur minerals have widely different surface and apparent chemical properties. Your response to different chemicals is also very different. To the date, certain polysaccharides such as guar gum and carboxymethylcellulose are used to lower silicate and non-sulphide gangue minerals during sulfide flotation. Their operation, however, is very variable and in some minerals they show unacceptable depressant activity and the effective dose per ton of ore is usually very high (as much as 0.0224 g to 4.546 kg (1 to 10 lbs / ton)). Its depressing activity is also included by its origin and is not consistent from batch to batch. In addition, these polysaccharides are also valuable sources of food, for example, their use as a depressant reduces their use as food and, the storage of them presents particular problems with respect to their attractiveness as feed for vermin. Finally, these are not easily visible or soluble in water and even where the aqueous solutions thereof can be made, they are not stable. U.S. Patent No. 4,902,764 (Rothenberg et al.) Discloses the use of synthetic copolymers based on polyacrylamide and terpolymers for use as mineral sulfur depressants in the recovery of valuable sulfide ores. U.S. Patent No. 4,720,339 (Nagaraj et al.) Describes the use of terpolymers and synthetic polyacrylamide-based copolymers as depressants for siliceous gangue minerals in the flotation benefit of valuable non-sulphided minerals, but not as depressants in the benefit of valuable sulfur minerals. The patent 339 teaches that such polymers are effective for the depression or sedimentation of the silica during the flotation of the phosphate, which also in the flotation stage uses the non-sulfided arms and collectors. The patentees do not teach that such polymers are effective depressants for unsulfurized silicate gangue minerals in the recovery of valuable sulfide minerals. In fact, such depressants do not exhibit adequate depressant activity for unsulfurized silicate minerals during the benefit of valuable sulfide minerals. US Patent No. 4,220,525 (Petrovich) teaches that polyhydroxyamines are useful as depressants for gangue minerals including silica, silates, carbonates, sulfates and phosphates in the recovery of valuable, non-sulfided minerals. Illustrative examples of the polyhydroxyamines disclosed include aminobutanetrols, aminipartites, aminoexitols, aminooptitols, aminooctitols, pentosa amines, hexose-amines, amino-tetroles, etc. U.S. Patent No. 4,360,425 (Lim et al.) Describes a method for improving the results of a foam flotation process for the recovery of valuable, non-sulfided minerals, where a synthetic depressant is added, which contains hydroxyl and carboxyl functional groups . Such depressants are added in the second stage flotation or amines of a double flotation process for the purpose of sedimenting the non-sulfided valuable minerals, such as phosphate minerals during the flotation of the silicate gangue amine from the concentrate of the second stage. This patent refers to the use of a synthetic depressant during amine flotations only. In view of the foregoing and especially in view of the teachings of U.S. Patent No. 4,902,764, which teaches the use of certain terpolymers and polyacrylamide-based copolymers for the depression or sedimentation of sulfide ores during the operation of sulfide ores valuable, it has unexpectedly been found that certain polymers, alone or in conjunction with polysaccharide, are indeed excellent depressants for non-sulphided silicate gangue minerals (such as talc, pyroxenes, olivins, serpentine, pyrophyllite, chlorites, biotites, amphibolites, etc. .). These synthetic polymeric depressants and mixtures with polysaccharides have now been found to be excellent alternatives for polysaccharides currently used alone, since these are easily miscible or soluble in water, and are non-hazardous and their solutions in water are stable. The use of these will increase the availability of polysaccharides as a valuable source of human food • and its operation is not variable. The polymers, however, can be manufactured to adhere to strict specifications and, consequently, consistency from batch to batch is guaranteed. Synthetic polymers lend themselves easily to the modification of their structure, which allows the development under design of depressors for a given application.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, a method is provided that comprises the benefit of valuable sulfide ore from minerals with selective rejection of the non-sulfided silicate gangue minerals, by: a. the provision of an aqueous suspension of ground product of finely divided mineral particles, of size adjusted for release, which contain valuable sulfide minerals and non-sulfur silicate filler or silicate gangue minerals; b. conditioning the slurry of milled product with an effective amount of depressant of the sifted ore or barrel of unsulfurized silicate, a collector of valuable sulfide ore and a foaming agent, the depressant comprises either (1) an alcohol polymer polyvinyl to which an acrylamide monomer and, optionally, a comonomer copolymerizable with the acrylamide monomer, or a mixture of polymers, or (2) a mixture of the polymer or polymers and a polysaccharide, and c. the collection of valuable sulfide ore that has a reduced content of filonian or silicate non-sulfur silicate bargain minerals by foam.

DESCRIPTION OF THE INVENTION, INCLUDING PREFERRED MODALITIES The polymeric depressants used in the present invention may comprise, like the grafted monomers, acrylamides such as acrylamide, per se, alkyl acrylamides such as methacrylamide, ethacrylamide and the like.

The comonomers may comprise any monoethylenically unsaturated monomer, or copolymerizable with the acrylamide monomer such as hydroxyalkyl acrylates and methacrylates, for example, 1,2-dihydroxypropyl acrylate or methacrylate; acrylate or hydroxethyl methacrylate; glycidyl methacrylate; acrylamido glycolic acid; hydroxyalkyl acrylamides such as N-2-hydroxyethylaclamide; N-l-hydroxypropylacrylamide; N-bis (1,2-dihydroxyethyl) acrylamide; N-bis (2-hydroxypropyl) acrylamide; and similar, acrylic acid; methacrylic acid; ammonium or alkali metal salts of acrylic and / or methacrylic acid; vinyl sulfonate; vinyl phosphonate; 2-acrylamido-2-methyl-propan-sulfonic acid; styrene sulfonic acid, maleic acid; fumaric acid; crotonic acid; 2-sulfoethyl methacrylate; 2-acrylamido-2-methyl-propan-phosphonic acid acrylonitrile; alkyl ethers of vinyl, such vinyl butyl ether, and the like. The effective weight average molecular weight range of the polyvinyl alcohols is surprisingly very high, ranging from at least about ten thousand, preferably from about thirty thousand to about millions, for example 2 million preferably up to about 1 million. Polysaccharides useful as a component in the depressant compositions used in the process of the present invention include guar gums; modified guar gums; cellulosic materials such as carboxymethylcellulose; starches and the like. Guar gums are preferred. The ratio of the polysaccharide to the grafted polymer in the depressant composition should vary in the range of about 9: 1 to about 1: 9 respectively, preferably up to about 7: 3 to about 3: 7, respectively, more preferably up to about 3: 2 to 2: 3, respectively. The dose of the depressant useful in the method of the present invention is in the range of about 4.53 g (0.01 pound) to about 4.53 kg (10 pounds) of depressant per tonne of ore, preferably from about 45.36 g (0.1 pound) to about 2.26 kg (5 pounds) per ton, more preferably from up to about 45.36 g (0.1 pound) to approximately 453.60 g (1.0 pound) per ton of ore.

When the mixtures of the polyvinyl alcohol polymers discussed above are used as depressants, these can be used in proportions of 9: 1 to 1: 9, preferably, 3: 1 to 1: 3, more preferably 3: 2 to 2: 3, respectively. The weight ratio of acrylamide to polyvinyl alcohol in the depressants used herein should be in the range of from about 99 to 1 to about 1 to 1, preferably from about 10 to 1 to about 4 to 1, respectively. The concentration of the optional copolymerizable comonomers should be less than about 50 p.sup., as a percent portion by weight, preferably from about 1 to about 30%, of the total monomers. The polyvinyl alcohol grafted with acrylamide monomer can be prepared by any method known to those skilled in the art, as taught in European Patent EPO-A-117978; Melnik et al; Dokl. Akad. Nauk Uter, SSR, Ser B; Geol Khim. Brol. Nanki (6), 48-51, Russian, 1987; Burrows et al; J. Photochem. Photobiol. A, 63 (1), 67-73, English, 1992. In general, the acrylamide monomer, alone or in conjunction with the optional comonomer, can be grafted onto the polyvinyl alcohol in the presence of a ceric ion catalyst, for example cerium ammonium nitrate, as a catalyst at a temperature in the range of about 10-50 ° with intermittent cooling for about 2-6 hours. The completion of the reaction is carried out after a constant viscosity of the solution is reached by raising the pH with dilute caustic solution to neutral or above. In general, the amount of catalyst employed should be in the range of from about 0.3 to about 5.0% by weight, based on the combined weight of the monomers to be grafted, preferably from about 0.8 to about 4.0%, on the same basis , resulting in the preferred range a grafted polymer having a more effective depressant activity. The new method for benefiting from the valuable sulfur ores using the synthetic depressants of the present invention provides excellent metallurgical recovery with improved grade. A wide range of pH and depressant dosage are permissible, and the compatibility of depressants with foamers and with collectors of valuable sulfur mine.ral is an advantage. The present invention is directed to the selective removal of non sulphided silicate filler or silicate gangue minerals that normally report to the concentrate by flotation of valuable sulfide ore, either due to natural flotation capacity or hydrophobicity, or otherwise. More particularly, the present method effects the depression or sedimentation of unulfurized magnesium silicate minerals while making possible the enhanced recovery of valuable sulfide minerals. In this way, such materials can be treated as, but are not limited to, the following: Talc Pirrofilite Pyroxene group of minerals Diopside Augite Batableblends Enstatite Hypersylte Ferrosilite Bronze Amphibolite group of minerals Tremolite Actinolite Anthophyllite Biotite group of minerals Flogopita Biotite Chlorite group of minerals Serpentine group of minerals Serpentine Cristolito Paligorskita Lizardite Anitgorite Olivine group of minerals Olivina Forsterite Hortonolite Fayalita The following examples are described for purposes of illustration only, and are not to be construed as limiting the present invention, except as described in the appended claims. All parts and percentages are by weight unless otherwise specified. In the examples, the following abbreviations designate the monomers used: AMD = acrylamide PVA = polyvinyl alcohol AA = acrylic acid MAMD = methacrylamide AN = acrylonitrile VBE = butyl vinyl ether t-BAMD = t-butylacrylamide HPM = 2-hydroxpropyl methacrylate AMPP = 2-acrylamido-2-methylpropan-phosphonic acid CMC = carboxymethylcellulose C = comparative Example Background 1 Preparation of the catalytic solution of Citrus Ammonium Nitrate 54.82 parts of ceric ammonium nitrate (0.1M) are dissolved in one liter of 1.0 N nitric acid.

Example Background 2 Graft Copolymerization To a solution of 5.0 parts of polyvinyl alcohol (molecular weight of about 10,000) in 150 parts of water, 30.9 parts of a monomeric 52% acrylamide solution are added. With good agitation, 5 parts of the aforementioned ceric catalyst solution are slowly introduced. The reaction mixture is maintained at 25-30 ° C with intermittent cooling with cold water. The graft polymerization is continued for 3 to 4 hours until a constant solution viscosity is obtained. The reaction is terminated by raising the pH of the mixture with dilute caustic solution to a neutral or slightly alkaline pH.

Examples Background 3 and 4 Following example 2 above, the graft copolymers of AMD and PVA of the higher molecular weight, for example, 20,000 and 50,000, are also prepared.

Example Background 5 A graft terpolymer is prepared by the addition of 30.9 parts of a solution of the 52% acrylamide monomer and 7.2 parts of acrylic acid monomer to a solution of 5.0 parts of PVA (molecular weight of 50,000) in 150 parts of water. A total of 10 parts of ceric catalyst solution is used for this preparation. Other copolymers are prepared in a similar manner, for example, using acrylonitrile and vinyl butyl ether.

EXAMPLES 1-10 A mineral containing approximately 3.3% Ni and 16.5% MgO (in the form of magnesium silicates) is milled in a roller mill for 5 min. to obtain a ground product with a mesh size of 81% -200%. The ground product is then transferred to a flotation cell and conditioned at natural pH (~ 8-8.5) with 150 parts / ton of copper sulphate for 2 min., 50 to 100 parts / ton of ethyl sodium xanthate per 2 min. and then with the desired amount of a depressant and an alcohol foaming agent for 2 min. The first stage flotation is then conducted through the air passage at approximately 3.5-5 1 / min., And a concentrate is collected. In the second stage, the milled product is conditioned with 10 parts / ton of ethyl sodium xanthate, and the specific amounts of the depressant and the foaming agent for 2 min. and a concentrate is collected. The conditions used in the second stage are also used in the third stage, and a concentrate is collected. All flotation products are filtered, dried, and rated. The results for the depressant activity of two AMD / PVA graft copolymers are compared with those of guar gum and polyvinyl alcohol in Table 1. In the absence of any depressant, the comparison of nickel is 96.6%, which is considered very high and desirable; MgO recovery is 61.4%, which is also very high, but considered highly undesirable. The Ni degree of 4.7% obtained is only slightly higher than that in the original feed. With guar gum at 420 and 500 parts / ton, the recovery of MgO is in the range of 28.3 to 33.5% which is considered lower than that obtained in the absence of a depressant, and Ni recovery is approximately 93% , which is lower than that obtained in the absence of the depressor. A reduction in the recovery of Ni has to be expected in the process of reducing MgO recovery, since there is invariably some mineralogical association of Ni minerals with Mg silicates and, when the latter are depressed, the minerals in the MgO are also depressed. Neither. When the graft copolymers of the present invention are also used, there is a much greater reduction in MgO recoveries compared to those with guar gums. The recoveries of Ni are also slightly diminished compared to that of guar gum, but in the grades of Ni in the concentrate they are much higher than those obtained with guar gum. These findings indicate the very strong depressant activity of the graft copolymers at all the doses used. These also suggest that much lower doses than graft copolymers can also be used; in this case Ni recoveries could improve while maintaining low MgO recoveries. The results also show that when a polyvinyl alcohol polymer is combined as such, for example, without grafting to the AMD monomer, the metallurgical performance is poor; depressant activity is very non-selective. The recovery is Ni is greatly reduced (82.9% versus 88% recovery for the graft copolymer under the identical conditions). In this way, the graft copolymer is much superior to polyvinyl alcohol as such.

Table 1 Feeding test: 3.31% Ni and 17.58% MgO EXAMPLES 11 -20 The gangue silicate minerals from the same ore as in Examples 1-10 are treated with a depressant dose of 453.6 g / ton (1.0 pound / ton) unless otherwise specified in accordance with the procedure of floating of it. The results are described in Table II, below, the lower the value under the head of the column, the higher the% recovery (gangue silicate) of the depressant.

Table II EXAMPLES 21 -24 A PVA graft copolymer is prepared according to the above Background Examples 1-5, with varying amounts of ceric iron catalyst. The results are shown in Table III, below, following the procedure of Examples 11-20.

Table III EXAMPLES 25-28 The flotation process of Examples 11-20 is again followed, except that different graft copolymers are employed. The results are described in the following table IV.

Table IV EXAMPLES 29-31 The flotation process of examples 11-20 is again followed, except that the molecular weight of the PVA is varied. The results are shown in table 5 below.

Table V EXAMPLE 38 The flotation process of Examples 1-10 is again followed, except that the depressant is a 1: 1 mixture of the depressants of Example 8 and Example 27. Similar results are achieved.

EXAMPLES 39-42 A mineral containing approximately 3.3% Ni and 16.5% MgO (in the form of magnesium silicates) is milled in a roller mill for 5 min. to obtain a ground product with a mesh size of 81% -200. The ground product is then transferred to a flotation cell and conditioned at natural pH (~ 8-8.5) with 150 parts / ton of copper sulphate for 2 min., 50 to 100 parts / ton of ethyl sodium xanthate per 2 min. and then with the desired amount of a depressant and an alcohol foaming agent for 2 min. The first stage flotation is then conducted through the air passage approximately 3.5-5 1 / min., And a concentrate is collected. In the second stage, the milled product is conditioned with 10 parts / ton of ethyl sodium xanthate, and the specific amounts of the depressant and the foaming agent for 2 min. and a concentrate is collected. The conditions used in the second stage are also used in the third stage, and a concentrate is collected. All flotation products are filtered, dried, and rated. The results for the depressant activity of a 1: 1 mixture of the AMD / PVA graft copolymer with guar gum are compared with those of the guar gum alone and the graft copolymer only at the same dose in Table VI. In the absence of any depressant, the comparison of Ni is 96.6%, which is considered very high and desirable; MgO recovery is 61.4%, which is also very high, but considered highly undesirable. The Ni degree of 4.7% obtained is only slightly higher than that in the original feed. With guar gum at 500 parts / ton, the recovery of MgO is in the range of 28.3% which is considered lower than that obtained in the absence of a depressant, and the recovery of Ni is approximately 93%, which is also less than that obtained in the absence of the depressant. A reduction in the recovery of Ni has to be expected in the process of reducing MgO recovery, since there is invariably some mineralogical association of Ni minerals with Mg silicates and, when the latter are depressed, some minerals are also depressed of Ni. With the AMD / PVA graft copolymer at the same dose, there is a significant reduction in MgO recovery compared to those with guar gums. In the case of the mixture of guar gum and the synthetic polymer at the same dose, however, there is additional increase in depressant activity compared to that of the two individual components. The degree of Ni in the concentrate is also increased. The results also suggest that higher doses of the mixture can be used; in this case, Ni recoveries could improve, while keeping MgO recoveries low.

Table VI Feeding Test: 3.31% Ni and 17.58% MgO Examples 43-53 When the procedure of Examples 39-42 is again followed, except that the depressant components are varied, as are their concentrations, as described in Table VII below, similar results are achieved.

Table VII * Produced with 2.6% Ce catalyst It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (11)

1. A method comprising the benefit of valuable sulfur ores, from ores or minerals, with selective rejections of non-sulphided silicate barge or silicate gangue minerals, characterized in that it comprises: a) the provision of an aqueous suspension of ground product of finely divided mineral particles, sized for release, which contain valuable sulphide minerals and non-sulphide, non-sulphide, and fillenian minerals; b) conditioning the slurry of milled product with an effective amount of depressant of the sifted mineral or non-sulphided silicate gangue, a valuable sulfide ore collector and a foaming agent, the depressant comprises either (1) a polymer of polyvinyl alcohol to which an acrylamide is grafted and, optionally, a comonomer copolymerizable with the acrylamide, or (2) a mixture of the polymer and a polysaccharide, and c. the collection of valuable sulfide ore that has a reduced content of non-sulphided silicate fillers or silicate gangue by foam flotation.

2. A method according to claim 1, characterized in that the weight ratio of the acrylamide to the polymeric alcohol is in the range of about 99 to 1 to about 1 to 1, respectively.

3. A method according to claim 1, characterized in that the graft polymer contains less than about 50 weight percent of said comonomer.

4. A method according to claim 1, characterized in that the molecular weight of the polyvinyl alcohol is at least about 10,000.

5. A method according to claim 1, characterized in that the comonomer, when present, is selected from the group consisting of acrylonitrile, (meth) acrylic acid and a vinyl alkyl ether.

6. A method according to claim 1, characterized in that the weight ratio of the acrylamide to the polyvinyl alcohol ranges from about 10 to 1 to about 4 to 1.

7. A method according to claim 1, characterized in that the graft polymer contains from about 1 to about 30 weight percent of said comonomer.

8. A method according to claim 1, characterized in that the molecular weight of the polyvinyl alcohol is at least 30,000.

9. A method according to claim 1, characterized in that the polysaccharide is guar gum.

10. A method according to claim 1, characterized in that the polysaccharide is carboxymethylcellulose.

11. A method according to claim 1, characterized in that the polysaccharide is starch.