The lead-zinc separation method is simpler, and satisfactory results are obtained using zinc sulfate. However, this situation is rarely seen. This is because the lead-zinc ore than lead addition and sometimes sphalerite contaminated with calcium ions, often associated with a pyrite. In particular, a sulphur-zinc ore of a pyrite-type lead-zinc ore has an iron sulfide content of 60 to 70% or more. Thus, it is difficult to separate lead from zinc and sulfur minerals by using only zinc sulfate to obtain a better sorting effect. In addition, in the case of external lead-zinc- copper or lead-zinc-copper-sulfur ore, when the ore contains secondary copper sulfide minerals, a large amount of copper ions in the pulp activates the sphalerite, which is more difficult to use in this case. The above method inhibits it. From the perspective of foreign mineral processing practice, the separation of lead and zinc is still dominated by the cyanidation process of zinc-reducing lead. Among them, the sodium cyanide-zinc sulfate method is more common, followed by the sodium cyanide-sulfuric acid method. In the latter, the secondary copper content is higher, and the ore containing more mud tends to obtain a better sorting effect.
Canada's Nova Scotia's new Gass River lead and zinc plant (with a daily processing capacity of 1,500 tons). Treatment of carbonate-type lead-zinc ore (including 2.8% lead, 4.2% zinc), in the lead and zinc sorting operation, using zinc sulfate-sodium cyanide process, the lead concentrate grade is 72%, and the lead recovery rate is 94. %, zinc concentrate grade of 62%, 92% recovery of zinc, the magnesium oxide content of only 0.35% zinc concentrates. In the Soviet Union, a Sarahsk lead-zinc plant with a high oxidation rate of lead and zinc and containing more copper is added with ammonium cyanide and zinc cyanide-sodium sulfide-sodium cyanide. sodium silicate, to improve lead, zinc recovery, especially in the recovery of aluminum oxide is particularly effective.
The cyanide-free process for lead and zinc sorting is used in addition to the sulfite process (including SO3) and sodium sulfite (North Brocken-Hill, Australia), which are commonly used in various plants in Japan. Nitrile-zinc sulfate sorting process. In the past one or two years, Japan and the Soviet Union reported two new lead-zinc sorting processes. Japan’s Zhongguang Jixiao et al. pointed out that the lead-zinc mixed concentrate was acidified and stirred in a 17% H2SO4 solution at 30 °C for 7 to 10 minutes, so that the surface of the galena was affected by H2SO4 to form PbSO4, which was inhibited. - Zinc sorting has created a new process for zinc sequestration. Soviet Kwasukesk lead -
The zinc smelting plant completely replaces sodium cyanide with high manganese potassium, which not only improves the grade of lead concentrate, but also reduces the zinc content in lead concentrate, and greatly simplifies the pharmaceutical system.
2. Copper-lead sorting
In the separation process of lead-zinc-copper (sulfur) ore, except for the separation process of copper-lead and zinc-(sulfur) is basically the same as the lead-zinc separation process, the main problem is concentrated in the separation process of copper-lead mixed concentrate. on. Copper - lead separation process are substantially three, i.e., suppression of copper cyanide is selected from lead, lead heavy chromate selected from copper and inhibition sulfite (and salts thereof) method. Currently, lead-zinc States metal ore dressing plant plurality gradually abandoned and conventional cyanidation method dichromate, to prevent the dissolved precious metal cyanide, to avoid cyanide, chromium-containing waste water.
Sulfuric acid does not inhibit chalcopyrite, porphyrite and chalcopyrite. Due to its cleaning of the copper mineral surface, it has the effect of activating copper minerals. The sulphite is not inhibited by the pure galena which is not cyanated, and the pH value of the slurry is less than or equal to 11. However, the galena with oxidized surface is strongly inhibited after pH >5. In the case of the same amount of sulfite of 1.5 kg / ton, galena is more suppressed as the surface oxidized degree of galena is deepened.
The above-mentioned selective inhibition of sulphite on copper and lead minerals is widely used in the industrial production of copper and lead separation. Due to the process of stirring, flotation and aeration of the slurry before separation of copper and lead, the surface of galena is differently programmed. Oxidized and thus inhibited by sulfite. In production practice, sulfite (or sulfurous acid) is often combined with other inhibitors to improve the sorting effect and stability. The main combinations are as follows:
(1) sulfur dioxide, starch method
This method is used by the American St. Bridge Minerals Company, the San Francisco Mine, the McGonagall, and the Brunswick Picking Plant in Canada. The copper-lead-zinc ore that is processed by the plant of the Trench of the Holy Bridge Minerals, such as the Krika, the Fugu, and the Nagano, has a copper-lead ratio of 30:1 to 50:1 or even 10 :1~100:1. Copper and lead are separated by sulfur dioxide and starch. Pre-separation pre-loading starch 0.25 ~ 0.5 kg / ton mixed, sulfur dioxide 1.5 ~ 3 kg / ton mixed, control the pulp pH value of 4.5 ~ 5, stirring 3 ~ 5 points, can lead to copper selection. The amount of sulfur dioxide and starch should be appropriate. If the sulfur dioxide is not enough, the starch will inhibit copper.
(2) sulfurous acid, slurry heating method
In the weakly acidic circuit, the collector adsorbed on the surface of the galena is preferentially desorbed as the slurry is heated above 60 °C, and the collector adsorbed on the chalcopyrite does not desorb even if the slurry is heated to 70 °C. Japan's Huagangtangwu and Songfeng and other plants have adopted the slurry heating method. The copper-lead mixed concentrate is blown into the steam, and the temperature of the slurry is raised to 60 ° C to carry out copper and lead separation. The raw ore grade copper in the small selection plant is 1.5% lead 1.6% and zinc 4.9%. The copper ore mixed flotation was carried out by controlling the pH of the slurry with calcium dioxide and calcium hydroxide. The copper-lead mixed concentrate is heated to 70 ° C, the pulp pH is 5.5, floating copper, and lead. The lead concentrate grade was 26%, the copper recovery rate was 81.8%, the lead concentrate grade was 58.1%, and the lead recovery rate was 70%.
(3) sulfurous acid - sodium sulfide method
The method can obtain better results for ores with high pyrite, high mud and high secondary copper sulfide.
(4) sodium thiosulfate (Na2S2O3) - ferric chloride method
The method can inhibit the galena which is strongly activated by copper ions and effectively separate the ore with complex composition. The Soviet Union's Czech Republic's selection of ore is complex, containing primary and secondary copper sulphide and copper oxide minerals. The galena is strongly activated by copper ions. In order to replace cyanide, no general sulfite method has been used. The Mihanopur Institute proposed that the Fe3+-S2O32-method can achieve a stable sorting effect on mixed concentrates. In 1977, the industrial test of lead-preventing copper was carried out at the selection of the factory in Czecho, and it was better. Index: copper concentrate grade 30.27%, separation operation recovery rate 90%; lead concentrate grade 68.5%, operation recovery rate 97%. After improvement from 1979 to 1980, a series of semi-industrial and industrial tests were carried out with sodium thiosulfate and ferric chloride as galena inhibitors, which proved that the secondary copper and copper oxide were 20-25%. Sulfide ore can be effectively separated and achieve higher indicators.
(5) Nuchar separation method
This method is a new separation method proposed at the 14th International Mineral Processing Conference. When dealing with difficult-to-select, low-grade copper-lead mixed concentrates, the inhibitory effect of inhibitors such as sulfurous acid-heating or dichromate is used. It decreases sharply with the increase in the content of sphalerite and pyrite in the ore. When using the sulphurous acid-heating method, the presence of gangue mud,
Then reduce the floating speed of copper. The new separation method is to remove the copper-lead mixed concentrate with activated carbon, add an equal amount of mixture of sodium chromate and water glass, and add CMC to suppress lead. Compared with sulfur dioxide-heating method, the grade of copper concentrate in semi-industrial test increased from 27.8% to 28.7%, the recovery rate of copper in separation operation increased from 92.9% to 94.7%, and the lead in copper concentrate decreased from 3.71% to 0.6%. The recovery rate of lead was increased from 79.7% to 97.4%.
Other methods are not the South Korean North Lotus Mining's NaHSO3 and the common cement-matched lead-preventing copper process. Separation of the copper-lead mixed concentrate of the Belovsov of the Soviet Union was carried out by using H2SO4 (800 g/ton) to suppress copper. And the copper-lead mixed concentrate with low copper content (lead 34.8% and copper 5.5%) in the Rajapura-Daribo deposit in Rajasthan, India. The effective inhibitor combination of galena is carbonic acid. A process such as a mixture of cerium , hydrofluoric acid and citric acid.
3. Zinc-sulfur sorting
In the lead-zinc polymetallic ore flotation process, the zinc-sulfur separation method, from the domestic and international ore dressing practices, mostly uses lime to inhibit iron sulfide minerals (pyrite and pyrrhotite). Copper sulfate activates sphalerite. A small number of cyanides are also used in individual plants during the separation of zinc and sulfur. It is worth noting that the Brunswick No. 12 Concentrator in Canada processes copper-lead-zinc ore using sulfur dioxide to lower the pH (4.5 to 4.8) and uses a steam heating method from a mixed concentrate containing lead, zinc, copper and FeS2. Only flotation of pyrite (floating pH of 5.0 to 5.3) improves the sorting effect and increases the lead concentrate grade by 8%. The West Germany Megan Plant uses a similar method to heat the zinc-sulfur mixed concentrate slurry to 80 ° C, treat it with sulfur dioxide at a pH of 4.6, inhibit sphalerite, flotation of pyrite, and make zinc concentrate. The grade increased by 7% to 55%.
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