Developing a multi-metal ore beneficiation process, we must consider a higher degree of beneficiation indicators and comprehensive utilization of mineral resources.
In order to deal with ores of different nature, the following four processes are mainly used in production:
The direct priority process of copper , lead and zinc in the sequential flotation process for the treatment of polymetallic ores can adapt to changes in ore grade and has high flexibility. It is suitable for primary sulfide ore with higher ore grade.
Most lead and zinc plants in foreign countries use the priority flotation process. For example, the sorting process used by Sweden's Lalsvall lead-zinc plant, one of the largest lead mines in Europe, is a typical priority process.
The whole mixing process adapts to the original ore in which the total content of sulfide minerals is not very high, and the sulfide minerals are closely symbiotic, complex in structure and fine in size. It can simplify the process, reduce the over-grinding of minerals, which is beneficial to sorting; can improve the processing volume per unit time; strengthen the flotation process by means of strong collectors and combined use of chemicals; it is possible to vulcanize lead and zinc The ore and oxidized ore are floated into a mixed concentrate; the harmful soluble salts and fine mud materials are sorted out in a timely manner together with the final tailings. The Soviet Almalake lead-zinc plant uses this process to achieve higher than the priority process. Lead concentrate grade increased by 10%. The zinc concentrate grade increased by 4.5% (absolute value), the comprehensive utilization rate of ore increased from 75.4% to 83.7%, and labor productivity doubled.
Copper-lead hybrid flotation process This is the most widely used process in production. When the grade of copper or lead in the ore is low, it is often economical to use such a process. Japan is famous for handling complex sulfide minerals. The process features copper, lead, zinc and sulfur in priority flotation, multi-stage fine grinding, sulfur dioxide and pulp heating. For example, the ore processed by the Tangwu Packing Plant is a copper-lead-zinc-sulfur polymetallic ore containing more than 20% of secondary copper. After the ore is ground, sulfuric acid is added, the pH is adjusted to 4.5, and lime is added to raise the pH to 6. Copper lead is sorted with zinc and sulfur.
The floatable process is based on the floatability of minerals in the ore, and the flotation is good, medium and poor, and then the flotation or selection is carried out as needed. Metal concentrate. The Soviet Zezkaz dry copper-lead mine does not pre-separate galena and chalcopyrite mud with inhibitors, then select secondary copper sulfide, and finally use butyl xanthate and black medicine in soda medium pH 8.2-8.5 At the time, coarse copper and lead are formed. The coarse-grained copper-lead mixed concentrate is separated from the fine particles by the zinc cyanide complex, which improves the copper recovery rate by 1.8% compared with the original mixing process; the lead concentrate contains copper from 5 to 6% to 4%; The amount of cyanide is reduced by 30%.
Most of the world's factories have increased the comprehensive utilization of various metals in ore as the focus of the reform process. The formulation of the flotation process depends primarily on the characteristics of the ore. The reform of the process structure includes the following aspects.
1. Grinding process and grinding site According to the mineral inlay particle size and structure, the commonly used grinding process has the following categories: 1) a fine grinding or rough selection of tailings re-grinding; 2) re-grinding of the mine; 3) Refining the coarse concentrate; 4) mixing the concentrate and grinding. In particular, the regrind (coarse concentrate, medium ore regrind) process in the selected circuit is the most common and one of the main directions for changing the process structure. For example, the use of the medium-mine re-grinding process includes Australia's New Broken-Hill, Mexico, Neka, and other selected plants. Lead-zinc plants such as Sid Meigen and Rupé Ales of Spain are used in the process of refining the coarse concentrate. The stage is selected by the United States, Kerr-Hill-Kellogg. The first mine in the process of returning to the mine will be selected from the plants of Sterling Lake, West Des Moines, Canada. The Australian Mount Isa plant has adopted this process to improve lead and zinc concentrate grades and recovery rates. When using the medium ore regrind process, the point of the mine should be minimized. Moreover, it is best to only clean the selected foam (the number and quality of the selected foam are easy to control). For example, the deer selection plant at the Kamio Mining Institute in Japan.
The above-mentioned several grinding processes are often combined in one plant, and even if there is only one grinding process, it may be carried out in stages. More typical is the Japanese Fengyu plant. Its ore is complex in nature, and there are as many as five grinding points (see the figure below), but it has obtained the first-class mineral processing index. In the second half of 1981, when the raw ore αpb = 2.38%, αZn = 8.27%, αs = 13%, the lead concentrate was βpb = 70%, εpb = 89.5%; zinc concentrate βZn = 57.5%, εZn = 95.3 %. [next]
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2. Heavy medium pre-selection (see pre-selection of ore for details)
Pre-floating of heavy medium before flotation of lead-zinc ore can greatly abandon waste (displacement of 35-40%) and increase the grade of ore. Guarantee or increase metal recovery rates as the ore grade gradually decreases. Pre-selection of lead-zinc ore heavy media – the flotation process is increasingly used. After the heavy medium pre-selection, the Lennogorsk plant in the Soviet Union treated the heavy products and the fine-grain grade ore separately, which increased the metal recovery rate by 2 to 2.5%, and also reduced the treatment cost. In addition, like the Soviet Zlynovsk and Tikrisk, the United States Bab-Barnes, the Canadian Sullivan, West Germany, the Japanese warehouse and the Amis-Salda in Masua, Italy ( The heavy medium pre-selection process has been successfully applied to the sulfurized, oxidized and mixed lead-zinc ore dressing plants such as Ammi-Sarda) and Poland's OIIъкцIII. According to recent reports, the Soviet Union has adopted a joint process including heavy medium, flotation, cyanidation and other processes to treat gold- and silver- containing lead-zinc polymetallic ores and achieved high targets. The ore contains 1.4% lead, 3.9% zinc, and 0.16% copper. The grades of lead and zinc concentrates were 53.69% and 61.6%, respectively. The recovery rates were 73.2% and 93.7%, respectively, and a medium mine containing 13% copper and 9.3% lead was obtained. The total recovery rates of gold and silver were as high as 90.1% and 90.2%, respectively.
3. Fractional flotation and intermediate flotation (1) Fractional flotation Fractionation flotation can expand the lower limit of fine particle recovery particle size and improve the sorting efficiency. The Japanese pine peak plant is processing mineral infiltration particle size. Fine, easy to muddy, with more mud (sometimes up to 30%) of "black ore", in the third selection of copper-lead flotation and copper-lead sorting operations and zinc selection, sweeping operations Both flotation flotation (with warm water operation) can improve the flotation index, the copper concentrate grade is increased from 18.1% to 22%; the lead concentrate grade is increased from 48.5% to 58.3%; the lead and zinc recovery rates are higher. The substantial increase was increased from 27.5% and 83.8% to 40.7% and 86.2% respectively.
(2) Separation of mud and sand This process is an effective measure to reduce the interference of slime and improve the efficiency of sorting. In the Soviet Lennogorsk, Zrenovsk, Misur and other plants, the Japanese Sakyamuni selection plant separately selected the removed primary slime, which significantly improved the selectivity of mineral sorting. The selection of factory indicators has been significantly improved.
(3) Intermediate flotation The intermediate flotation under coarse grinding conditions is an effective measure to reduce the mineral mudation of the monomer dissociation state. For example, the Soviet Almalake Lead-Zinc Plant selected a part of the foam product in the mixed flotation head to directly enter its final stage without the normal selection of the front work. The Misuer plant uses intermediate flotation and the use of non-polar agents to increase the lead and zinc grades by 10.1% and 2.5%, respectively, and the lead and zinc recovery rates by 0.7 to 1.5 and 3.4 to 4.1%, respectively.
4. interference and solutions regarding the activity of many lead-zinc ore pyrite there is a certain amount of flotation pyrite good activity in the traditional lead selected operating conditions, it tends to go up with galena, when the increase When pH is inhibited, galena is inhibited. At the same time, sphalerite is often floated due to the increase of pH value, which causes the operation to pull up and the pressure cannot be pulled. The ore dressing index is often caused by lead and zinc. They are high and very unsatisfactory, and even using a lot of cyanide does not help. Therefore, the long-term interference with pyrite, which is similar to the floatability of galena, is regarded as a difficult problem to solve. After more than ten years of continuous production practice, I have explored the following solutions.
(1) Changing the flotation sequence of traditional useful minerals The general flotation sequence of lead-zinc ore is galena-sphalerite-pyrite. For the refractory ore with the above characteristics, it can be used to cause the pyrite to float out with the galena prior to the sphalerite, and then to separate the lead and sulfur. Japan's Fengyu plant is using a lead-sulfur mixed flotation process to solve the interference of that part of the active pyrite, and another part of the floatable pyrite is still placed at the back of the main process. Go to the election. In Meigen, West Germany, about 10% of the colloidal pyrite in the ore is also floatable. Before 1974, the conventional flotation sequence was used to obtain only lead concentrate of βPb=25%; εPb=37% index of. In 1974, a special high-alkali operation was used to suppress sulfur and lead. After floating lead, it was not floating zinc. Instead, it floated the colloidal pyrite first, then floated zinc, and finally floated the common pyrite (see the figure below). . [next]
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(2) Special operating conditions For the interference of some active pyrite in the ore mentioned in the previous section, in the use of the preferential flotation process, in addition to the solution to change the flotation sequence, special operating conditions can also be used: 1) Inhibition of pyrite with a large amount of lime (pH > 11.5); 2) Harvesting of lead ore with high-grade xanthate 3) Adding all the yellow medicines of the rough selection to the first-stage ball mill . Zinc sulfate-based agents can also be used to inhibit sphalerite when preferentially selecting lead using this set of operating conditions.
Flotation of galena with xanthate collector at high pH has been considered impossible in the past, based on a suitable pH range of galena from 7 to 9, and when the pH is >9, lead The mine is suppressed. In addition, in the preferential flotation of galena, emphasis is placed on the use of a yellow bean drug with good selectivity and weak harvesting ability. In fact, the same is true. If the diced yellow syrup is used in the weak alkaline pulp, it can cause operational disorder. As for the place where the xanthate is added, it is generally customary to add the xanthate to the agitation tank before the flotation. The reason why it is added to the ball mill is also due to the high alkali condition. In short, the three special operating conditions mentioned here are not used in general. 1974 West Germany Megan plant W. Latsch first discovered this set of special operating conditions. Under this set of conditions. Pyrite, including the part of pyrite that is similar in floatability to galena in general, loses its floatability, while galena remains buoyant, thus expanding both The difference in floatability, so as to achieve the purpose of preferential flotation galena.
Magne's ore has 10% oxidized colloidal pyrite, which is finer than 10μ in size and has high floatability, which has become a major problem in the flotation technology of Megan. However, since the use of this set of operating conditions, the Megan plant has increased the lead recovery rate from 33% to 60%, and the lead grade of lead concentrates has increased from 25% to 50%. Igen used isopropyl xanthate when selecting lead.
(3) Application of anti-floating properties Colloidal pyrite in ore often interferes with zinc flotation, which makes the zinc concentrate grade not high. For this problem, the Brunswick mine in Canada successfully applied the hot sulfur dioxide method to reverse flotation of colloidal pyrite before 1970.
The so-called hot sulfur dioxide method is to pass the SO 2 in the first stirred tank to the slurry fed to the reverse flotation pyrite, so that the slurry is weakly acidic, and then heated in the second stirred tank by steam, as the temperature rises. SO 2 desorbs and decomposes the xanthate on the surface of the ore particles. This process is faster for copper, lead and zinc sulfide ore, and slower for pyrite, resulting in a gap between the two, at 75 ° C ~ At 80 ° C to achieve the best economic level, so that colloidal pyrite can be produced as a foam product, while copper, lead, zinc sulfide ore as the final concentrate remains in the tank, in each condition, temperature is the most important of. After the slurry is cooled, the sulfide minerals such as copper, lead and zinc can be regained floatability without adding a collector.
The Brunswick No6 plant uses SO 2 to inhibit galena, chalcopyrite, sphalerite at pH 4.5 to 4.8, and then heats the slurry to 79.4 ° C, flotation of pyrite and pyrrhotite. . Compared with the method of inhibiting pyrite flotation copper-lead-zinc mixed concentrate, the mixed concentrate grade is higher under the same recovery rate. The plant uses the hot sulfur dioxide method to pass only one rough sweep operation, and the mixed concentrate grade is increased from Pb+Zn+Cu=42% to 57%.
The Brunswick No12 plant also used this method to reverse flotation of pyrite from zinc concentrates, increasing the zinc concentrate from 50% to 57.8%.
In 1976, the hot sulfur dioxide process of the Megan plant was officially put into operation. The total zinc mine contained about 35% zinc. In the first stirred tank, SO 2 was added about 3.5 kg/ton, and the pH was 4.2. In the second stirred tank, steam was heated to 80 ° C; flotation using a coarse three fine; the level of zinc concentrate in the tank increased from 53.2% in the past to 54.75, up to 58%; zinc recovery rate was 81%.
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