MXPA05003708A

MXPA05003708A - Process for the beneficiation of sulfide minerals.

Info

Publication number: MXPA05003708A
Application number: MXPA05003708A
Authority: MX
Inventors: G Magliocco Lino
Original assignee: Cytec Tech Corp
Priority date: 2002-10-15
Filing date: 2003-10-01
Publication date: 2005-07-28
Also published as: DE60312541D1; OA12943A; AP2005003271A0; PL375072A1; AR041586A1; EP1556170A1; BR0315150B1; RU2318607C2; AP1920A; PL202110B1; BR0315150A; PE20040429A1; EP1556170B1; ATE356670T1; WO2004035218A1; PT1556170E; AU2003279843A1; CA2501079C; AU2003279843B2; RU2005114538A

Abstract

Froth flotation processes, useful for beneficiating base metal m ineral values from metal sulfide ore, utilize a collector comprising an N-butoxycarbonyl-O-alkylthionocarbamate selected from the group consisting of N-butoxycarbonyl-O-methylthionocarbamate, N-butoxycarbonyl-O-etkylthionocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-O-buylthionocarbamate, N-butoxycarbonyl-O-pentylthionocarbamate, and N-butoxycarbonyl-O-hexylthionocarbamate.

Description

PROCESS FOR THE BENEFIT OF SULFIDE MINERALS FIELD OF THE INVENTION This invention relates to foam flotation processes for the recovery of metal values of base metal sulfide ores. More particularly, it relates to processes employing sulfide ore collectors comprising certain N-butoxycarbonyl-O-alkylthiocarbamate compounds which exhibit excellent metallurgical development over a wide range of pH values. BACKGROUND OF THE INVENTION Foam flotation is a process widely used for the benefit of minerals containing valuable minerals. A common foam flotation process involves intermixing an aqueous slurry containing finely ground mineral particles with a foam or foaming agent to produce a foam. The mineral particles containing the desired mineral are preferably adhered to the foam due to an affinity between the foam and the mineral exposed on the surfaces of the mineral particles. The resulting beneficiated minerals are then collected by separating them from the foam. Chemical reagents known as "harvesters" are commonly added to the slurry to increase the selectivity and efficiency of the separation process, see U.S. Patent No. 4, 584, 097, which is incorporated herein by reference.

Ref. : 162875 Foam flotation is especially useful for separating valuable finely ground minerals from their associated gangue or for separating valuable minerals from one another. Because of the large scale at which extraction operations are commonly conducted and the large difference in value between the desired ore and the associated gangue, even relatively small increases in separation efficiency provide substantial gains in productivity.

BRIEF DESCRIPTION OF THE INVENTION Unexpectedly, it has now been found that the N-butoxycarbonyl-O-alkylthiocarbamates selected from the group consisting of N-butoxycarbonyl-O-methylthiocarbamate, N-butoxycarbonyl-O-ethylthiocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-O-butylthiocarbamate, N-butoxycarbonyl-O-pentylthiocarbamates, and N-butoxycarbonyl-O-hexylthiocarbamate are particularly effective in foam flotation processes. A preferred embodiment provides a foam flotation process for the benefit of a mineral, comprising: forming a sludge comprising water and particles of a mineral, the mineral containing sulphide minerals; the intermixing of sludge with effective amounts of a foaming agent and a collector to form a foam containing beneficial sulfide minerals; and that it collects the beneficiated sulfur minerals; The co-collector consists of an N-butoxycarbonyl-O-alkylthiocarbaitiate selected from the group consisting of N-butoxycarbonyl-on-thiocarbamate, N-butoxycarbonyl-O-ethylthiocarbamate, N-butoxycarbonyl-0-propylthiononocarbamate, N-butoxycarbonyl-O-butylthiocarbamate, N-butoxycarbonyl-O-pentylthiocarbamates, and N-butoxycarbonyl-O-hexylthiocarbamate. These and other modalities are described in more detail below.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In preferred embodiments, the sulfide and mineral metal values are recovered by foam flotation methods in the presence of the collector, the collector comprising at least one N-butoxycarbonyl-O-alkylthiocarbamate selected from the group consists of N-butoxycarbonyl-O-methylthiocarbamate, N-butoxycarbonyl-O-ethylthiocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-0-butylthiocarbamate, N-butoxycarbonyl-O-pentylthiocarbamate, and N-butoxycarbonyl-O-hexylthionecarbamate . The term "N-butoxycarbonyl-0-alkylthiocarbamate" is used herein to refer to the compounds in the above-mentioned group, which include isomers thereof. For example, N-isobutoxycarbonyl-O-isobutylthiocarbamate is an example of a preferred N-butoxycarbonyl-O-butylthiocarbamate. Other preferred examples of N-butoxycarbonyl-0-alkylthiocarbamate include N-isobutoxycarbonyl-O-ethylthiocarbamate, N-isobutoxycarbonyl-O-hexylthiocarbairiate, and N-butoxycarbonyl-O-isobutylthiocarbamate. Preferably, the N-butoxycarbonyl-O-alkylguidocarbamate are used as sulfide collectors in a foam flotation process that provides an improved benefit of sulfide mineral values from base metal sulfide minerals over a range of pH values and more preferably low, neutral, slightly alkaline and highly alkaline conditions. The N-butoxycarbonyl-O-alkylthiocarbamates can be produced in various forms. For example, butyl chloroformate can be reacted with a thiocyanate salt, for example, sodium thiocyanate, to form an intermediate butoxycarbonyl isothiocyanate. Thiocyanate salts and butyl chloroformate can be obtained from commercial sources; Butyl chloroformate can also be synthesized by reaction of phosgene with butanol. The intermediate butoxycarbonyl isothiocyanate can be reacted with an alcohol ROH to form the desired N-butoxycarbonyl-O-alkylthiocarbamate. The group R in the ROH represents an alkyl group having a form of six carbon atoms. Examples of ROH include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol and isohexanol.

Those skilled in the art understand that the terms "benefit", "benefit" and "benefited" refer to a mineral enrichment process in which the concentration of the desired mineral and / or metal in the ore increases as the process proceeds. . For example, a preferred foam flotation process comprises the formation of a sludge comprising water and particles from a mineral, the internal mixture of the sludge with a foaming agent and a collector to form a foam containing beneficiated minerals, and which collects the minerals benefited. The mineral particles in the slurry are preferably made by reducing the size of the ore to provide flotation-sized mineral particles, in a manner generally known to those skilled in the art. The particle size at which a particular mineral is reduced in size for the purpose of releasing the mineral of value from the associated or worthless gangue, that is, the size of release, commonly varies from mineral to mineral and may depend on countless of factors, for example, the geometry of the mineral deposits within the mineral, for example, striations, agglomerations, comatrices, etc. A determination that the particles have reduced in size to release size can be made by microscope examination using methods known to those skilled in the art. Generally, and without limitation, the appropriate particle sizes vary from about 50 mesh to about 400 mesh. Preferably, the ore is reduced in size to provide flotation size particles in the range of about +65 mesh to about mesh -200. Preferably especially for use in the present method are the base metal sulfide ores which have been reduced in size to provide from about 14% to about 30% by weight of +100 mesh particles and from about 45% by weight. % up to about 75% by weight of mesh particles -200 in size. The reduction in the size of the mineral can be carried out according to any method known to those skilled in the art. For example, the ore can be crushed to a size of -10 mesh followed by wet grinding in a steel ball mill to the desired mesh size, or flint stone grinding can be used. The sludge (also known as a pulp or slurry of pulp) can be formed in various ways known to those skilled in the art, for example, by intermixing ore particles of release size with water, by grinding the ore in the presence of water, etc. The pH of the sludge can be adjusted at any stage, for example, by adding a pH modifier (acid or base) to the slurry or grinding during size reduction, to provide the mud at any desired pH. Preferred pH modifiers include sulfuric acid and lime so, for example, a good benefit can be obtained at pulp mud pH values in the range from about 7 to about 12, and particularly in the pH range of from about 9 to about 1.5.The pH of the sludge can be adjusted at any point in the mineral flotation process for foam flotation or in the same foam flotation process. Mineral particles preferably contain from about 10% to about 60% pulp solids, more preferably from about 25% to about 50% pulp solids, more preferably from about 30% to about 40% solids of pulp, by weight based on the total weight of the sludge. According to a preferred embodiment, the flotation of copper, zinc and lead sulphides is carried out with a pH in the range of from about 6 to about 12, more preferably from 9 to about 11.5. It has been found that N-butoxycarbonyl-O-alkylthiocarbamate harvesters provide exceptionally good harvester resistance, together with excellent collector selectivity, even at reduced collector doses, when foam flotation is conducted in the aforementioned pH range. The sludge is preferably conditioned by intermixing it with effective amounts of a foaming agent and a collector comprising at least one N-butoxycarbonyl-O-alkylguidocarbamate to form a foam which. contains sulfur minerals benefited. The foaming agent, collector and sludge can be intermixed in any order. For example, the collector can be added to the slurry and / or to the milling according to conventional methods. By "effective amount" is meant any number of respective components which provide a desired level of benefit of the desired metal values. Any foaming agent known to those skilled in the art can be employed in the foam flotation process. Examples, without limitation, of suitable foaming agents include: straight or branched chain low molecular weight hydrocarbon alcohols, such as Cs to C8 alkanes, 2-ethyl hexanol and 4-methyl-2-pentanol (also known as methyl isobutyl carbinol or MIBC), in addition to pine oils, cresylic acid, glycols, and polyglycols. Mixtures of foaming agents can be used. The effective amounts of foaming agents for a particular foam flotation process can be determined by routine experimentation. Common amounts of foaming agent are often in the range of from about 0.01 to about 0.2 pounds (4.5 to 9 grams) of foaming agent per tonne of treated ore, although greater or lesser amounts of foaming agent can be effective in particular situations .

The N-butoxycarbonyl-O-alkylthiocarbamate collector can be used alone, in combination with another, and / or in combination with other sulfide mineral collectors such as xanthates, xanthogen, thiophosphate, thiourea, and / or thionocarbamate formats, for example. , dialkylthionecarbatonates. A collector comprising an N-butoxycarbonyl-O-alkylthiocarbamate is preferably intermixed with the foaming agent and the pulp mud in amounts ranging from about 0.005 to about 5 pounds (2.27 to 2270 grams) of harvester per tonne of ore in the mud, more preferably around 0.1 Ib (45.4 g) to about 2 Ibs / ton (900 gr / ton), on the same bases. In foam flotation processes in which it is desirable to selectively collect copper sulfide ores and selectively reject iron sulfide ores such as pyrite and pyrrhotite, in addition to other gangue sulphides, the harvester is preferably used in amounts from about 0.01 Ib / ton (4.54 g / ton) to about 5 lbs / ton (2.27 kg / ton) of ore in the mud. In the processes of flotation of sulfur foam in volume, higher levels of collector are often preferred. The actual amounts of collector for a particular foam flotation process can be determined by routine experimentation. The intermixing of sludge with an effective amount of a foaming agent and an effective amount of N-butoxycarbonyl-O-alkylthiocarbamate is preferably conducted in a manner that produces a foam containing the beneficiated sulfide minerals. The formation of the foam can be facilitated by the use of proper mixing conditions and / or injection of air into the mud. Routine experimentation according to conventional foam flotation methods can be used to determine the appropriate conditions for floating the desired sulfide mineral values in the foam concentrate and preferably, selectively reduced or rejected pyrite and other gangue sulfides. The N-butoxycarbonyl-O-alkylthiocarbamates, although virtually insoluble in water, have the distinct advantage of being easily dispersible. For example, when added to a flotation cell, these collectors provide enhanced copper recovery in the first flotation stage along with general improved copper recovery, which indicates improved flotation kinetics, as shown in the examples provided below. N-butoxycarbonyl-O-alkylthiocarbamates harvesters can be used to selectively concentrate or collect certain metal-containing sulfides, particularly those of copper, lead and zinc from other gangue sulfides, for example, pyrite and pyrrhotite, and other materials of gangue, for example, silicates, carbonates, etc.

These collectors can also be used in situations where it is desirable to collect all the sulfides in a mineral, including sphalerite (ZnS) and iron sulfides, that is, pyrite and pyrrhotite, in addition to the copper sulfide minerals. It will be appreciated by those skilled in the art that various omissions, additions and modifications can be made to the processes described above without departing from the scope of the invention, and all modifications and changes were projected to fall within the scope of the invention, as it was defined by the appended claims. EXAMPLES 1-6 A copper ore from Sudarnérica was used in the following flotation tests. This mineral contains around 1.2% copper, 4% iron and 278 ppm molybdenum. This mineral also contains the usual silicate or silicon gangue. The ore was ground to 75% passing a 100 Tyler mesh (150 μta) using a mild steel bar mill containing 7.5 kg of mild steel bars. The crushed solids are 66% in water. The lime was added to the bar mill in an amount sufficient to provide a flotation pH of 11., similar to that used in the concentrator. The diesel fuel (10 grams per ton of ore in the pulp) is also added to the mill to promote the flotation of Mo. The pulp of ore is then discharged into a flotation cell and the volume of the pulp is adjusted to 30- 34% solids for flotation. A set of Denver D-12 flotation machine at 1000 rpm was used for the flotation tests. The pulp was stirred to ensure homogeneity. Then a collector was added as shown in Table 1 and a foaming agent to the pulp to allow the condition for 2 minutes. The foaming agent used is a mixed product containing the AEROFROTH® 7SA foam former, commercially available from Cytec Industries, Inc., West Paterson, New Jersey. The foaming dose is 15 grams per tonne of ore in the pulp (g / t) for all tests. The flotation concentrates were collected at intervals of 1, 3 and 6 minutes. The concentrates and bottoms were filtered, dried and evaluated for Cu, Fe and Mo. The results shown in Table 1 clearly show the superiority of the N-butoxycarbonyl-O-alkylthiocarbamate collectors over previous harvesters, which either produce low recovery or poor selectivity against iron (recovery of high Fe). Because of the large scale at which extraction operations are commonly conducted at the large difference in value between the desired ore and the associated gangue, these increases in separation efficiency provide substantial gains in productivity.

TABLE 1 EXAMPLES 5-10 A copper / molybdenum mineral from South America was used in the following flotation tests. This mineral contains around 1.4% copper, 5.8% iron and 113 ppm molybdenum. This mineral also contains the usual silicate or silicon gangue. The ore was milled for 80% passing a 65 mesh Tyler mesh (212 μt) using a mild steel bar mill containing 7.5 kg of mild steel bars. The crushed solids are 66% in water. The lime was added to the bar mill in an amount sufficient to provide a flotation pH of 10-10.5, similar to that used in the concentrator. A collector in the dose shown in Table 2 and a foamer (9 g / t) were added to the mill a. along with diesel fuel (6 g / t to promote the flotation of Mo). The foaming agent used is the foaming agent AEROFROTH® 70, an isobutyl carbinol metal product commercially available from Cytec Industries, Inc.-, West Paterson, New Jersey. The mineral pulp is then discharged into a flotation cell and the pulp volume is adjusted to 30-34% flotation solids. A Denver D-12 flotation machine set at 1000 rpm was used for these flotation tests. The pulp was stirred to ensure homogeneity. Additional foam (8 g / t) was then added to the pulp to allow the condition for 2 minutes. The flotation concentrates were collected at intervals of 1, 3 and 6 minutes. The concentrates and bottoms were filtered, dried and evaluated for Cu, Fe and Mo. The results shown in Table 2 clearly show the superiority of the N-butoxycarbonyl-O-alkylthiocarbamate collectors, which produce higher recoveries of copper ores and molybdenum compared to previous harvesters. Due to the large scale at which extraction operations are commonly conducted and the large difference in value between the desired ore and the associated gangue, these increases in separation efficiency provide substantial gains in productivity.

TABLE 2 EXAMPLE 11 Synthesis of isobutoxycarbonyl isothiocyanate: 136.58 grams (1 mole) of 99% isobutyl chloroformate were added to a 50% thiocyanate solution containing 81 grams (1 mole) of NaSCN, 81 grams of water, 4.36 grams of quinoline (catalyst) and 1.8 grams of Na2CO3 (base) while maintaining the reaction at a temperature of 25-30 ° C with stirring. The reaction is monitored for chloroformate consumption during the formation of a top layer of isobutoxycarbonyl isothiocyanate (approximately 4 hours).

The contents of the reaction vessel are filtered to remove the solid sodium chloride and isobutoxycarbonyl isothiocyanate is isolated in the form of a layer which is separated from the aqueous layer. EXAMPLE 12 Synthesis of N-isobutoxycarbonyl-O-isobutylthiocarbamate: A process initiated as described in Example 11 was continued by returning the isolated isobutoxycarbonyl isothiocyanate layer to the reaction vessel and adding 1.3 moles of isobutyl alcohol. The reaction temperature was maintained around 20-25 ° C for about 4 hours. The resulting thionocarbamate / isobutyl alcohol mixture was run in vacuum at 23-25 inches (584-635 mm) of Hg and 50 ° C to remove water and some excess alcohol, followed by filtration to remove precipitated salt . About 215 grams of the final product were obtained in the form of a mixture of about 190 grams of N-isobutyloxycarbonyl-O-isobutylthiocarbamate and about 25 grams of isobutyl alcohol. EXAMPLE 13 Synthesis of N-isobutoxycarbonyl-O-isobutylthiocarbamate: A process initiated as described in Example 11 was continued by returning the isolated isobutoxycarbonyl isothiocyanate layer to the reaction vessel and adding 1.3 moles of hexyl alcohol. The reaction temperature was maintained around 20-25 ° C for about 4 hours. The resulting thionocarbamate / hexyl alcohol mixture was depleted in vacuo at 23-25 inches of Hg and 50 ° C to remove water and some excess alcohol, followed by filtration to remove the precipitated salt. About 215 grams of the final product were obtained in the form of a mixture of about 190 grams of N-isobutyloxycarbonyl-O-hexylthiocarbamate and about 25 grams of hexyl alcohol. 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.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property. A foam flotation process for the benefit of a mineral, characterized in that it comprises: formation of a sludge comprising water and particles of a mineral, the mineral contains sulfur minerals; intermixing the sludge with effective amounts of a foaming agent and a harvester to form a foam containing beneficial sulfide minerals; and collect the beneficiated sulfur minerals; the collector consists of an N-butoxycarbonyl-O-alkylthiocarbamate selected from the group consisting of N-butoxycarbonyl-O-methylthiocarbamate, N-butoxycarbonyl-O-ethylthiocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-O-butylthiocarbamate, N-butoxycarbonyl-O-pentylthiocarbamate and N-butoxycarbonyl-O-hexylthiocarbamate. 2. The process according to claim 1, characterized in that the collector is intermixed with the sludge in an amount ranging from about 0.005 (2.27 grams) to about 5 pounds (
2.270 grams) per ton of ore in the slurry .
3. The process according to claim 1, characterized in that the collector is intermixed with the sludge in an amount ranging from about 0.1 (45.4 grams) to about 2 lbs (900 grams) per ton of ore in the slurry .
4. The process according to claim 1, characterized in that the sludge has a pH in the range of from about 6 to about 12. The process according to claim 1, characterized in that the sludge has a pH in the interval from about 9 to about 11.
5.
6. The process according to claim 1, characterized in that the N-butoxycarbonyl-O-allylthiocarbamate is N-butoxycarbonyl-O-ethylthiocarbamate.
7. The process according to claim 1, characterized in that the N-butoxycarbonyl-O-alkylthiocarbamate is N-butoxycarbonyl-O-butylthiocarbamate.
8. The process according to claim 7, characterized in that the N-butoxycarbonyl-O-butylthiocarbamate is selected from the group consisting of N-isobutoxycarbonyl-O-isobutyl-thiocarbamate and N-butoxycarbonyl-1-O-isobutylcarbamate.
9. The process according to claim 1, characterized in that the N-butoxycarbonyl-O-alkylthiocarbamate is N-butoxycarbonyl-O-hexylthiocarbamate.
10. The process according to claim 1, characterized in that the ore comprises a metal selected from the group consisting of copper, lead and zinc.
11. The process according to claim 10, characterized in that the N-butoxycarbonyl-O-alkylthiocarbamate is selected from the group consisting of N-isobutoxycarbonyl-O-ethylthiocarbamate, N-butoxycarbonyl-O-sobutylthiocarbamate, N-isobutoxycarbonyl-O- isobutylthiocarbamate and N-isobutoxycarbonyl-O-hexylthiocarbamate.