With the Dexing copper mine production capacity continues to increase, the amount of molybdenum metal selected ore reached 1000t / a or more, the average copper concentrate containing more than 0.2% Mo, by taking certain measures in 1998, produced more than 200 t of molybdenum Concentrate. However, due to many reasons, the production technology economic indicators have not yet reached an acceptable level. Therefore, the new copper-molybdenum separation technology and its application in production are discussed in order to reduce the cost of molybdenum selection or increase the recovery rate and improve the economic benefits of enterprises. Dexing Copper Mine, but also has a positive significance for other similar mines.
There are two methods for separating copper and molybdenum: one is copper-suppressing molybdenum; the other is molybdenum-free copper floating. Currently, there is only two copper and molybdenum processing plant (US Bingham and silver bell) is the use of the second, most of the copper and molybdenum processing plant is using the first method, the first method is discussed below.
The copper-molybdenum mixed concentrate is first dehydrated and dehydrated by a thickener. The strengthening measures are deactivated activated carbon, aerated oxidation, steam digestion, etc., followed by the addition of copper inhibitors such as Na 2 S, NaHS, NaCN, Knox. The intensive measures for reducing the amount of inhibitors are steam flotation, nitrogen flotation, acid addition, flotation column flotation, etc., followed by removal of molybdenum concentrate by addition of hydrochloric acid or chloride to remove copper, lead , calcium. Etc. Finally, HF or (NH 4 )HF is leached with sulfuric acid to remove SiO 2 . Many of the above measures have been applied abroad for more than 10 years or more, and are still in the experimental stage in China. Dexing Copper Mine has carried out many experimental research work around reducing the amount of Na 2 S in molybdenum operation, and has achieved certain results, providing a scientific basis for future industrial production.
I. New technology for copper and molybdenum separation
(1) Passivation of copper-molybdenum mixed concentrate
The passivation of copper-molybdenum mixed concentrate refers to the reduction of the activity of copper minerals by means of aeration, steaming and the like. The thickener dehydrates and removes the drug, only removes the remaining xanthate from a part of the pulp. By introducing air into the slurry, steaming, adding Na 2 S, activated carbon, etc., the xanthate is oxidatively decomposed or desorbed, so that the subsequent operation Na 2 The amount of copper inhibitor such as S is decreased.
In addition, the storage of copper-molybdenum mixed concentrate has a significant effect on the separation of copper and molybdenum. This is due to the strong oxidation of the surface of the chalcopyrite during storage, which is easily suppressed and the amount of inhibitor is greatly reduced. This has been practiced by Dexing Copper Mine. Proved.
The United States' Serat plant has a design capacity of 90,000 t/d. The original ore grade: containing 0.32% of Cu and 0.03% of Mo. The grade of copper-molybdenum mixed concentrate: containing 25% Cu, containing Mo2% to 3%, After concentration, the pump was pumped to a stirred tank, then into a steam generator and steamed at 82.2 ° C for 15 min.
The Kueqiong plant in Peru has a processing capacity of 46,000 t/d. The ore grade: containing 1.169% Cu and 0.026% Mo. The copper-molybdenum mixed concentrate is concentrated into a row of 4 sets of 1.4m×1.4m. The Denver scrubber scrubs at high concentration and high speed to make the surface of the molybdenum mine clean, which is beneficial to interact with the fuel oil. Before being selected, it is diluted with the cooling water (hot water) of the nitrogen plant.
Mexico's La Caledade plant has a processing capacity of 90,000 t / d, the original ore grade: containing 0.6% to 0.8% of Cu, containing Mo 0.02% to 0.04%, the design process contains copper and molybdenum mixed concentrate storage and Passivation, scrubbing, high-energy scrubbing found no significant effect in the production, so the scrubbing operation was cancelled. The copper-molybdenum mixed concentrate is concentrated, and the bottom stream is sent to one of three 9.2m×9.2m stirred storage tanks, each of which is full, ie 8h loading, 8h passivation and 8h unloading, pulp passivation At 24h, the slurry is aerated at the time of passivation to lower its pH to better inhibit the uplift of copper minerals during molybdenum flotation.
Canada's Nelocks and Gibraltar plant, after the copper-molybdenum mixed concentrate is concentrated, using multiple stirring, the mixing time is longer, the yellow medicine is destroyed, and the slurry is uniform and the ore grade is stable, which is beneficial to the flotation operation.
(2) Adding acid to adjust pulp
The inhibition of copper minerals by sodium sulfide is related to HS-ions, and the hydrolysis of sodium sulfide is related to the pH of the medium.
The following reactions occur when sodium sulfide is hydrolyzed:
Na 2 S+2H 2 O 2 Na + +2OH - +H 2 S↑
H 2 SH + +HS - , K 1 = 3.0 × 10 -7 ;
HS - H + + S 2 - , K 2 = 2.0 × 10 -15 .
When pH is less than 7, the hydrolysis of sodium sulfide will produce a large amount of hydrogen sulfide gas, at a pH of about 9, a solution of sodium sulfide in 99% or more based on anionic HS - in the form, the pH value is too high, [HS - drop] Moreover, luminance also affected floatability of molybdenite, in fact, mixed copper-molybdenum concentrate most of the pulp pH value greater than 12 (due to the large amount of lime added to the job to inhibit pyrite), dehydration and drug alone (Thicker), new water slurry, can not reduce the pH of the pulp to a suitable level, therefore, acid addition technology has emerged.
La. Caledad plant, adding sulfuric acid to control the pH value of rough selection, if the copper mineral is mainly chalcopyrite, the pH is adjusted within the range of 8-9, if the copper mineral is dominated by chalcopyrite, pH The value is adjusted between 7.5 and 8.0.
The bottom stream of the copper and molybdenum mixer was pumped into the mixer (3 sets in series), and sulfuric acid was added to the first mixer to reduce the pH of the slurry to 8.5.
The bottom of the copper and molybdenum blending machine of the Gibraltar plant was stirred by two stages. The first stage was stirred for 6 hours, and the second stage was added with sulfuric acid for 15 minutes to reduce the pH of the slurry to 8. The plant uses a combustion-type nitrogen generator for nitrogen for nitrogen-flotation flotation, and CO 2 , a by-product of the nitrogen generator, is used for slurrying (instead of sulfuric acid) to reduce the cost of acid.
(3) Nitrogen-filled flotation
Sodium hydrosulfide reacts with oxygen in the slurry and oxidizes to sulfite, thiosulfate and sulfate, thereby losing the inhibitory effect. Therefore, the actual consumption of sodium hydrosulfide is much larger than the theoretical consumption, which is also lowering it. One of the main ways of dosage is to reduce the oxygen content in the slurry by means of nitrogen filling and heating, thereby reducing the oxidation of copper mineral inhibitors by oxygen.
In the study of the cause of the consumption of Knox's pharmacy, John F. Delany found that when using copper instead of air for copper and molybdenum separation, the dosage of the drug can be greatly reduced (1/5 to 1/2). And obtained the US patent in April 1972. In January 1981, the Peruvian Kwahonet plant was built to build a nitrogen plant for nitrogen-filled flotation, which reduced the amount of arsenic Knox's agent by 50% to 70%, and then gradually extended it to Other selection plants.
The rough selection of the plant and the first selection of nitrogen in Gibraltar, the average nitrogen consumption is 0.137m3 / s, the amount of sodium hydrosulfide is reduced from 9.25kg / t to 2.2kg / t, a reduction of 76%, nitrogen by combustion nitrogen The generator is supplied with its by-product CO 2 instead of sulfuric acid.
Peru's Kueqiong selection plant rough selection and 1 or 2 selection operations using nitrogen instead of air, plus coarse selection of hot water (nitrogen plant cooling water) flotation, reducing arsenic Knox dosage by more than 50% , significantly improved the dehydration and drying effect of copper concentrate.
There are two main problems in nitrogen charging in conventional flotation machines: one is nitrogen evolution; the other is air inhalation. It is easier to solve the above difficulties by nitrogen filling in the flotation column. In addition, Wimco has developed an inert gas flotation machine for nitrogen filling, which is composed of a series of closed flotation tanks that trap the surrounding air in the air. Oxygen is consumed by the oxygen-consuming agent, and almost all of the remaining nitrogen is nitrogen. The slurry is nitrogen-filled, thereby generating nitrogen foam. The nitrogen in the foam product is recovered by a deaerator, and then returned to use to form a closed circuit, thereby reducing the amount of nitrogen added. At the very least, a nitrogen felt was developed to cover the flotation machine to accelerate the promotion of the new nitrogen-filling process.
(4) Flotation column flotation
Column flotation was germinated in the United States in 1919. In the 1960s, Canadians invented flotation columns. In the mid-1960s, many domestic plants (Dexing Copper Mine, Jinduicheng Molybdenum Mine, etc.) replaced flotation with flotation columns. Machine, because the foaming device pores are easy to scale, block, and the research work is not enough, in the mid-1970s, the rate was untied. After the 1980s, the research and application of foreign flotation columns culminated, and the technology of foamer and the scale-up of industrial flotation columns were greatly developed, and microbubble flotation columns were developed. control Bureau international Limited), Jameson flotation column (University of Newcastle) and filling flotation columns and other media (Michigan technological University), China University of Mining also developed a swirl microbubble flotation column for peat Flotation.
The occurrence of molybdenum ore is characterized by high dispersion and fine grain impregnation, so the Mo content in the copper-molybdenum ore is low (Dexing copper deposit contains Mo0.01%), which determines that the separation process is characterized by multi-stage grinding and multiple times. Sorting, the number of sorting is 5 times, and 12 times, usually 8 times. Fine grain and multiple selections determine the superiority of applying flotation column.
The Lonnex plant replaced the original 8 selections with two flotation columns. With the same beneficiation index, the energy saving was 244kW.h.
Canada's copper-molybdenum plant uses two 0.9m × 0.9m × 12m, one 0.45m × 0.45m × 12m flotation column for 3 times, replacing the original flotation machine 5 times, molybdenum The recovery rate increased from 55% to 72% to 80%, and the molybdenum concentrate grade reached Mo52%.
Canada's Gaspe plant has replaced eight selections with two flotation columns of 0.95m and 0.46m, significantly increasing the recovery of molybdenum.
(5) New copper inhibitor
At present, most of the copper inhibitors used in copper and molybdenum plants at home and abroad are inorganic compounds. The main problems in use are: 1 large dosage. 2 toxic. 3 There is a potential safety hazard. 4 pollute the environment and ecological balance when discharging. Therefore, it is very necessary to develop a new type of copper inhibitor with high efficiency, low toxicity and low cost.
Organic compound agents have good development prospects due to their good stability, long potency, low dosage, especially sulfhydryl compounds such as sodium thioglycolate, thioglycolic acid and ammonium thioglycolate.
Jinduicheng Siping Plant uses sodium thioglycolate instead of sodium cyanide. The amount is 1/2 of the latter. The Xiaosigou copper mine replaces sodium sulfide with sodium thioglycolate. The amount is 1/44 of the latter. Molybdenum ore has also achieved similar results with the Xiaosigou copper mine. GR Ramandola and other tests have found that the combination of sodium thioglycolate and activated carbon is better.
Philippe has also developed the OrformD series of new inhibitors of copper and iron. Laboratory and field experiments have shown that in the case of no reduction in the selection index, the dosage is 1/2 of sodium cyanide. It is harmless to the environment and operators, and can reduce the cost of flotation by 10% to 20%.
(6) Electrochemical controlled flotation
The oxidation-reduction potential in the slurry is closely related to the behavior of the mineral. By controlling the oxidation-reduction potential of the slurry, two or more minerals can be separated. This method has been popularized and applied in some mines in China, but it is used in the production of copper-molybdenum separation. Practice has not been reported. In fact, as early as 1972, Changde et al. used electrochemical flotation to conduct copper-molybdenum separation studies. By selecting an appropriate slurry potential, copper molybdenum or molybdenum-free copper can be suppressed. Electrochemical flotation can eliminate the need for a collector. Changing the hydrophobicity of the mineral surface, the addition of a collector enhances the selectivity of the separation.
The test proves that when the slurry potential is -250~-500mV, the chalcopyrite is inhibited, the pulp potential is greater than -250mV, the chalcopyrite will float, and when the sodium sulfide inhibitor is used, the flotation time will be extended and the slurry concentration will be increased. When the temperature is lowered, the slurry potential will gradually increase, so sodium sulfide needs to be added in multiple stages and the amount is large. However, if the amount of sodium sulfide is too large, it will cause waste of the drug and adversely affect the subsequent operations. At present, only the experience is used to judge whether the amount of sodium sulfide is suitable or not. Therefore, the fluctuation is large. If the potential of each point can be displayed online using an industrial slurry potential meter, the amount of sodium sulfide can be strictly controlled, and the amount of sodium sulfide can be strictly controlled. Pharmacy cost.
(7) Solar heating and drug removal
At present, about 70% of energy comes from oil , and about 30% comes from coal. With the shrinking of these resources, new energy sources such as solar energy, wind energy and nuclear energy are receiving more and more attention. In recent years, the application research of solar energy has developed rapidly. Switzerland has developed a pointed-hat solar reactor for the production of cement. The most widely used solar thermal utilization device in China is the solar water heater, which has entered the stage of commercialization and industrial production. Commercialization and industrial application of solar disinfection technology may have three demonstration projects to date: two for treating groundwater in the United States and one for treating industrial wastewater in Spain. The use of solar energy for slurry heating has not been reported.
Before the separation of copper and molybdenum, it is necessary to remove the xanthate from the surface of the chalcopyrite in the pulp to deactivate the chalcopyrite, while the thickening machine is dehydrated, stored, oxidized and decomposed, and the drug is limited. If it is used in areas with long sunshine hours, use solar energy. Temperature (than the boiler heating economy) pulp in the thickener, accelerate the separation of xanthate, will help reduce the amount of sodium sulfide.
Second, the prospect of the application of new molybdenum technology in Dexing Copper Mine
Since 1991, Zhongnan University of Technology and other units have conducted research on copper and molybdenum separation processes and equipment in Dexing Copper Mine, such as pulsating high gradient magnetic separation, packed flotation column, nitrogen-filled flotation, sodium thioglycolate, etc. , achieved certain results.
The Dexing Copper Mine has a long sunshine period. If a solar collector system suitable for slurry heating is developed, increasing the slurry temperature by 30 °C can reduce Na2S consumption and increase the molybdenum recovery rate by 2% to 4%.
The copper-molybdenum mixed concentrate was stored in a thickener (30m) for 1.5 months. The amount of sodium sulfide is 10kg/t lower than that of fresh samples. If three agitator (series) aeration passivation process is adopted, the oxidative decomposition of xanthate on the surface of copper minerals can be accelerated, and the amount of sodium sulfide can be effectively reduced. The copper-molybdenum mixed concentrate is adjusted to pH 9 with sulfuric acid, the sodium sulfide can be reduced by 5kg/t, the nitrogen-filled flotation can reduce the sodium sulfide by 60%, and the filling static flotation column is 1m×6.4m (1 unit) instead of the existing One coarse and three fine, the amount of sodium sulfide is reduced by 36kg/t, and the power is saved. A 0.6m×6.4mSFC flotation column has been installed on site to replace the existing 4-8 selections due to liquid level control. Unstable, high alkalinity pulp is prone to fouling on the surface of the column packing, and production is also unstable. If the acid slurry is added in the agitation tank, the two selections are replaced by two flotation columns, which is expected to greatly reduce the production cost of molybdenum.
The molybdenum plant has purchased the [HS - ] analyzer (offline measurement), and the slurry (HS - ) is measured periodically to control the amount of sodium sulfide. When the conditions are ripe, it is expected to install an industrial slurry potentiometer in the production (online measurement). It is more intuitive, quicker and more accurate to guide the addition of the drug.
Due to the inherent disadvantages of sodium sulfide, it is necessary to find a highly effective new copper inhibitor. Therefore, sodium thioglycolate or other organic agents should be further studied.
Domestic copper-molybdenum separation technology still has a gap from abroad. Domestic enterprises should speed up the introduction, digestion and absorption of new technologies in this field, so that they can be applied to industrial production as soon as possible. In this way, the production of molybdenum by-product can be improved and molybdenum can be reduced. Product production costs, enhance the ability to participate in international market competition.
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