PROCESS FOR THE SELECTIVE SEPARATION OF A COPPER MOLYBDENUM ORE

Abstract: A process for separation of the mineral components of a copper/molybdenum sulfide ore by flotation including (a) crushing and grinding the ore to liberate the minerals; (b) in a primary flotation circuit, adding a molybdenum collector selected from the group of hydrocarbon oils, and a frother; (c) floating a primary (molybdenum) concentrate in the primary circuit in the absence of a copper collector; (d) directing the primary molybdenum concentrate to an upgrading separation circuit to produce a final molybdenum concentrate; and (e) directing the non-float of the primary circuit to a secondary scavenger circuit for recovery of copper and additional molybdenum with addition of a copper collector, the process being conducted at a natural pH essentially determined by the ore composition and the quality of the water used to form the pulp, without addition of substantial amounts of alkaline or acid pH modifiers sufficient to change the pH.

Description: PROCESS FOR THE SELECTIVE SEPARATION OF A COPPER MOLYBDENUM ORE Background of the Invention a) Field of the Invention The present invention relates to an improved process for the selective separation of the components of a copper molybdenum (Mo--Cu) ore by flotation. More particularly, the present invention relates to a process for such separation conducted at a natural pH (i.e. without addition of alkalies (such as lime) or.acids in amounts sufficient to substantially modify the pH) and without the addition of a copper collector in the primary flotation circuit, which leads to the recovery of a primary Mo-Cu concentrate. b) Description of the Prior Art In conventional flotation systems for copper ores with recoverable molybdenum by-product values, the ore is first crushed and ground with lime usually added to depress pyrite. The ore is then tr ated in a primary flotation circuit after copper collector and frother have been added. The copper rougher concentrate thus obtained contains most of the copper and a substantial portion of the molybdenum. This rougher copper concentrate is then subjected to several stages of cleaner flotation (usually after a regrind operation) to pro¬ duce a finished copper concentrate. This concentrate contains substantially all of the molybdenite recovered in the rougher circuit. The copper concentrate is then treated in a series of separation steps designed to separate the molybdenite, a by¬ product in many copper ores, as a high-purity concentrate. A major problem with this system is that lime which is invariably used, may depress a portion of the molybdenum, caus¬ ing a decrease in the obtainable recovery of Mo 2 S mineral. Another major problem with the conventional system is that it requires molybdenum recovery from a copper concentrate with a high reagent content. Because of this, the separation of molybdenum from the copper minerals is especially difficult. A complex secondary separation system is necessary, which is costly, requires a high level of copper depressants, and may cause lowering of molybdenum recovery. • Objects of the Invention One object of the present invention is to provide a process for the separation by flotation of the components of a copper ore (with molybdenum as a by-product) by flotation. This process affords a convenient, inexpensive, and efficient method of molybdenum recovery at an acceptable grade. Another object of this invention is to provide a pro¬ cess for such separation, which can be conducted at a natural pH and avoids use of lime and other pH modifiers. Another object of this invention is to provide a pro¬ cess for such separation which avoids use of substantial amounts of depressant for copper minerals. Another object of this invention is to provide a pro¬ cess or such separation that avoids use of a copper collector i_ * the primary flotation circuit. Another object of this invention is to achieve the recovery in the primary flotation circuit of a concentrate substantially enriched in molybdenum which, because of its enhanced molybdenum content, can be further separated into a molybdenum concentrate with less reagents and in a substantial¬ ly smaller number of cleaning stages, and which affords sub¬ stantially enhanced recovery of the molybdenum mineral initial¬ ly contained in the ore. The copper content of this primary flotation circuit, after the cleaning stages, can be diverted to the copper circuits. Hence, the overall copper recovery of the system is not jeopardized. These and other objects of this invention will be ap¬ parent to one of ordinary skill in the art in light of the present description, accompanying claims and appended drawing Summary of the Invention The present invention is directed to a process for th separation of the mineral components of an ore, said ore com¬ prising minerals selected from the group consisting of base metal sulfides, including copper and molybdenum sulfides as well as pyrite, said process comprising: (a) grinding said ore with water to form an ore pulp of appropriate particle size distribution for flotation; (b) in a primary flotation circuit, adding a molyb¬ denum collector selected from the group of hydro carbon oils along with a frσther; (c) in the absence of a copper collector, floating a primary copper molybdenum concentrate with said primary concentrate containing a portion of the copper minerals in the feed to said primary cir cuit; (d) recovering the molybdenum from the primary conc trate in a cleaner circuit, and directing the cleaner tailings to the copper circuit; directing the non-float of said primary circuit a secondary copper molybdenum flotation circuit and recovering a scavenger copper concentrate w a small proportion of the molybdenite; said process being conducted at a natural pH essentially det mined by the ore composition and the quality of the water us to form said pulp, without addition of substantial amounts o alkaline or acid pH modifiers sufficient to change the pH. Brief Description of the Drawings Fig. 1 is a flowsheet of a copper-molybdenum ore sep ration scheme by flotation in accordance with the present in vention. Fig. 2 is a water-balance flowsheet for a copper- molybdenum flotation process, as it is typically practiced in the Southwestern United States where water is in short supply. Detailed Description of the Invention In accordance with the present invention, copper ore with associated molybdenum values, from a mine is crushed and ground to the required particle size to form the flotation fee and ore pulp. Preflotation conditioning of the ore, if any, may be conducted during or after the wet grinding stage and is comple ted before the first flotation stage. Preconditioning is marked as 1 in Fig. 1. According to the present invention, t only preconditioning that may be necessary at this stage woul require addition of very small amounts of redox agents, such a sodium sulfide, hydrogen peroxide, etc. , or aeration. Combine contributions from ore mineralization, degree of surface oj .da tion and water chemistry (unless modified) can result in vary¬ ing degrees of copper and iron sulfide mineral recovery along with the molybdenite, in the primary molybdenum rougher stage. Preflotation conditioning of the ore, with specific reagents, conducted during or after the grinding stage, may be necessar to prevent or minimize this recovery of copper and iron sul¬ fides. The reagents used may be of reducing characteristics, such as hypochlorites, peroxides or atmospheric air. The amounts required are just sufficient to prevent or minimi _ ** t aforesaid recovery of copper and iron sulfides along with' he molybdenite during the primary molybdenite flotation stage. ' other words, the amount of the redox reagent, or the extei-t o aeration, is preferably just sufficient to prevent or minimiz copper sulfide and pyrite flotation, without affecting molyb¬ denite flotation, and does not affect the pH. In the vast majority of the cases, no lime or other pH modifiers are adde (or, if added, lime is in extremely small amounts compared wi the conventional lime circuits and only for protective alkali nity, i.e. to prevent equipment corrosion) . No copper collector is added in the primary molybdenite flotation circuit. However, a small amount of a hydrocarbon oil is added as a moly-collector, at 2 in Fig. 1, along with a frother. Suitable hydrocarbon oils include vapor oil, diesel oil, fuel oil, etc. Preferably, the hydrocarbon will contain as little wax fraction as possible. The primary flotation circuit produces a rougher molyb¬ denum concentrate containing some copper and a non-float. This concentrate, which is substantially enriched in moly as compared to conventional circuits, is then reground if necessary and directed to cleaner stages which lead to the production of a final molybdenum concentrate. The cleaner stage simplification and cost savings achieved by the present invention are also substantial. The non-float of the primary circuit is directed to a copper flotation circuit. The non-float contains some of the copper and the remaining non-floating minerals. Copper col¬ lector is added at 3 in Fig. 1. Whether an oxidation/reduction agent is added or not (either before primary flotation at 1, or before the scavenger flotation at 4 in Fig. 1) depends in large measure on the natu¬ ral oxidation/reduction conditions of the ore and the water used in the flotation process. The copper rougher concentrate is typically directed to regrind and cleaner operations, resulting in production of a final copper concentrate, a final tailings product, and possi¬ bly a secondary molybdenum concentr?te. This latter concen¬ trate, when produced, represents a small proportion of the total moly content of the original ore, because of the effi¬ ciency of the present primary flotation circuit in recovering molybdenite. This secondary molybdenum concentrate may be recycled to the primary molybdenum circuit, or to the molyb¬ denum cleaner circuit, depending on the molybdenum assay. Further separation of the scavenger concentrate may require addition of a small amount of an oxidation/reduction agent sufficient to minimize pyrite flotation. The process of the present invention does not need to employ cyanide. Aeration is advantageously used instead of (or in addi tion to) a redox additive to control the redox potential of th pulp. Aeration can be used at 1 in the primary flotation cir¬ cuit, or at 4 in the first scavenger circuit. Advantages of the present process include simplifica¬ tion of the flotation scheme and savings in all reagents, in¬ cluding those resulting from the omission of lime and the mini mal — if any — addition of a redox agent, and also in frothe and collector consumption. Other advantages stem from the improvement in moly recovery and/or grade. . Suitable molybdenum-copper ores for practice of the present process include-copper-molybdenum sulfide ores which contain chalcopyrite and chalcocite. The present process is particularly suited for ore separation in plants where the water is recycled. In fact, t present process can be advantageously introduced in separatio plants where a major portion of the water is reclaimed as il¬ lustrated in Fig. 2 (Prio ' r Art) . This is so because the addi tion of reagents (including- collector and redox reagent, if any) is so minimal the? ■ ■"-_they do not accumulate in the reclaim water. In Fig. 2, app oximately 60% of the water in the syst is reclaimed after flotation of a rougher concentrate, 4. Additional water is reclaimed from the non-float scavenger circuit, 2. All reclaimed water is combined at 3. The invention is further illustrated below by referen to specific examples. However, the scope of the present inve tion is not limited to these examples. Example 1 Ore: 500 g of copper-moly ore from Chino Mines Divi¬ sion, Kennecott Copper Company containing mostly chalcopyrite. Water: 350 ml process H 2 0 (from stage 1 of Fig. 2) . After grinding (for 6 min.) Na 2 S was added to the pul (the equivalent of 50g/ton of ore) in a conditioning step (1 min.). The pulp was aerated for about 2 minutes with mixing and then the air was turned off. Fuel oil, 2 drops, was adde to the pulp together with 6 drops of MIBC, a frother. After flotation of the rougher concentrate (3 min.), 2 drops of 269 a copper collector were added in a conditioning stage (2 min. and the first scavenger concentrate was floated (4 min.). Subsequently, one more drop of the copper collector was added (2 min.) and the second scavenger concentrate was floated. T electrochemical potential was measured and found to be +40 in the first conditioning stage, during aeration, and in the rougher concentrate flotation step, and +50 in the first sca¬ venger flotation step. The pH was 7.5 during aeration, 7.8 during conditioning, 8.0 during flotation of the primary con¬ centrate and 8.2 during flotation of the secondary concentrat The results were as follows: Analysis Distribution Product Weight MO CU Mo CU Rougher Cone. 2.7 0.338 17.75 60.75 34.1 1-Scavenger Cone. 3.62 0.032 18.06 9.59 57.8 Primary Cone. 5.79 0.147 17.94 70.35 91.9 Non-float 94.21 0.0038 0.096 29.65 8.0 Calculated Head 100.00 0.121 1.129 Example 2 Ore: 500 g of the same copper- oly ore as in Example Water: 350 ml Process H 2 0 (from stage 1 of Fig. 2) . The ore was ground for 6 min. and only frother (2 dro of MIBC) was added. Fuel oil (6 drops) was added in a first conditioning stage (1 min.) and the pulp was aerated for two min. No sodium sulfide or other redox reagent was added. T rougher concentrate was floated (3 min.) and the non-float w conditioned (2 min.) with the addition of 2 drops of copper collector. The first scavenger concentrate was floated (4 min.) and the non-float was conditioned for 2 minutes with 1 . additional drop of copper collector (2694) after which the second scavenger concentrate was floated. The results were as follows: Analysis Distribution Product Weight MO _____ Mo Cu Rougher Cone. 0.72 0.878 8.11 54.36 5.13 1-Scavenger Cone. 3.88 0.036 24.42 12.01 83.29 Primary Cone. 4.60 0.168 21.87 66.37 88.43 Non-float 95.40 0.0041 0.138 33.63 11.57 Calculated Head 100.00 0.0116 1.137

Claims: What is claimed is: 1. A process for the separation of the mineral comp nents of an ore, said ore comprising minerals selected from t group consisting of base metal sulfides, including copper and molybdenum sulfides, as well as pyrite, said process compris¬ ing: (a) crushing and grinding said ore to liberate said minerals; (b) in a primary flotation circuit, adding a molybde num collector selected from the group of hydroca bon oils, and a frother; (c) floating a primary (molybdenum) concentrate in said primary circuit in the absence of a copper collector; (d) directing the primary molybdenum concentrate to upgrading separation circuit to produce a final molybdenite concentrate; and (e) directing the non-float of said primary circuit a secondary scavenger circuit for recovery of copper and additional molybdenum with addition o a copper collector; said process being conducted at a natural pH essentially dete mined by the ore composition and the quality of the water use to form said pulp, without addition of substantial amounts^ of alkaline or acid pH modifiers sufficient to change the pH. 2.. The process of claim 1, wherein the pulp is sub¬ jected to aeration for a period of time sufficient to at le s minimize flotation of copper and iron sulfides in the primary molybdenite circuit. 3. The process of claim 1, wherein an oxidizing or reducing agent is added to said ore at a point before the add tion of the molybdenum collector in an amount sufficient to a least minimize the flotation of copper and iron sulfides alon with molybdenite. 4. The process of claim 2, wherein an oxidation or reduction agent is added to said ore at a point before the addition of the molybdenum collector in an amount ranging be¬ tween about 0 to 50 g/ton of ore. 5. The process of claim 1, said process being con- ducted without any addition of said pH modifiers. 6. The process of claim 1 further comprising additio of a copper collector to said non-float and floating a copper concentrate. 7. The process of claim 6 comprising the addition of an oxidation/reduction agent to maximize pyrite non-floatabi- lity at the natural pH of the system, in order to float a rougher copper concentrate for further up-grading to a final copper concentrate. 8. The process of claim 4 wherein said agent is sul¬ fide ion. 9. The process of claim 7 wherein said agent is adde in an amount ranging between about 0 and 50 g/ton of ore.

Inventors: ARBITER NATHANIEL, VARGAS ALFREDO P, ARBITER, NATHANIEL, VARGAS, ALFREDO, P.
Applicants: PHLOTEC SERVICES INC, PHLOTEC SERVICES, INC.
Application year: 1986
Main classification: B03B1
IPC codes: B03B1, B03D1