Application of flotation method in Yanjin Mine Concentrator

Rock gold mine flotation beneficiation plant is the most widely used as a dressing method. Especially when dealing with smaller particles of gold, gold-bearing sulfide good floatability quartz vein ore, and a processing polymetallic ores and gold-bearing sulfide ores containing graphite aspect of the most common application. As early as 1936, Shandong Linglong built a 150-ton/day concentrator and used the flotation method to select gold. 1938, Jiapigou, Lao Jin plant and Kiyohara gold plant also began to use copper flotation process gold ore. Between 1940 and 1942, several gold-removing factories, such as the Aoya Cliff, the backwaters, and the official residence, also used the flotation method to select gold. According to the production records of the Jiapigou gold-removing plant between the Republic of China and the Republic of China in the thirty-fourth year of the Republic of China (average index): the amount of gold-bearing copper concentrate produced by flotation operation is 4% of the original ore; the concentrate grade : Gold 90 g / ton, silver 264 g / ton, copper 6.8%. During the Liberation War, except for a few gold mines such as Jiapigou and Laojinchang, which were liberated in the first place, they were still produced by flotation. Other gold mines destroyed equipment when Japan surrendered, and most of them stopped production. Before the founding of New China until 1965, the gold mines gradually recovered, and large-scale mechanized gold-sorting plants had not yet been built. Flotation processes for gold producers were few. After 1965, a number of large-scale (500 tons/day or more) ore dressing plants such as Wulong, Jinchangyu and Zhaoyuan were completed and put into operation. The flotation method has begun to be widely used, which has effectively promoted the improvement of flotation technology. After the 1970s, with the rapid development of gold production, the number of new or expanded concentrating plants in gold mines has increased, and the application of flotation has increased accordingly. By 1985, most of the rock gold mines were selected by flotation. The flotation technology has been continuously improved and the beneficiation index has been significantly improved. According to the survey and statistics of the flotation production indicators of 33 key state-run rock gold mines in China in 1985, the ore recovery rate (theory) is: the average recovery rate of sulfide ore flotation gold is 90%, and a few mines have reached 92- 95%: 95.27% in Xincheng, 95.18% in Zhaoyuan, 94.36% in Jinchang, 94.19% in Suichang, 93.99% in Qishanzi, 93.08% in Erdaogou, 92.79% in Jinchanggou, and average recovery of flotation in gold-bearing ore The rate is 75%, some mines are more than 85%, and Shaoguan Gold Mine is 87.16%.

First, the flotation process is constantly improving

The rational choice of the process depends on the type of ore and the nature of the ore. Some mines modify the original design process in time according to the changes in the nature of the ore, and obtain obvious technical and economic effects.

The production practice proves that for the ore of gold minerals with uneven embedding, aggregate embedding and fine grain embedding, the stage grinding and stage selection can greatly improve the gold sorting effect. Hunan Xiangxi Gold Mine adopts the re-election-flotation combined process for stage grinding and stage selection, obtaining better indicators and increasing the gold recovery rate by more than 6%. Shandong Jiaojia Gold Mine used flotation method to treat gold-bearing oxidized ore. The recovery rate of ore dressing was 79.49%. After the stage selection, the recovery rate increased to 84.35%. Wulong Gold Mine adopted a mercury -flotation process in 1959, a grinding and one selection process, and the mercury-mixed tailings entered flotation. The total recovery rate of mercury amalgamation and flotation was 60%. In 1963, it was changed. After the second mill was selected, the total recovery rate of amalgamation and flotation was increased to 78-80%, and significant results were obtained.

In some rock gold mines, the ore contains more mud, which adversely affects the flotation process. Therefore, in some large flotation plants, the “mud sand sorting” process is often used to separate the slime. The two gold mines in Jiaojia and Xincheng of Shandong Province are seriously damaged by the surrounding rock of the ore body. In addition, the tailings are used to fill the mining method in the underground, so that some tailings are mixed into the ore, which results in excessive mud content in the flotation operation. The concentrator then treated the slime separately using a mud-sand separation process. The slime produced by washing the crushing workshop, that is, the single spiral graded overflow, is dewatered by a Φ900 mm thickener and sent to an independent slime flotation circuit. Satisfactory results were obtained by separate flotation using specific process conditions. After the sedimentation of the Xincheng Gold Mine, the flotation concentrate grade was increased from 135 g/ton to 140 g/ton, and the recovery rate was increased from 93.05% to 95.01%.

In terms of the internal structure of the flotation process, the gold selection process is simpler than the flotation process of polymetallic ore. However, in view of the process characteristics of gold ore, China's flotation plants often adopt a process structure that is compatible with them. Among them, there are two processes that use more priority enrichment and centralized selection.

Some ores often contain a certain amount of easy-floating gold minerals, which can be quickly floated in the first or second flotation tanks of roughing operations under rough grinding. Scratch it out to obtain a qualified concentrate that greatly exceeds the final concentrate grade. The timely selection of this part of the easy-floating minerals can avoid the loss of repeated cycles in the subsequent flotation circuit, and realize the sorting principle of “early harvest and fast harvest”. This process of “rough selection of concentrates” is called the “priority enrichment” process. Gold mines such as Wulong, Jinchangyu and Jiaojia have adopted this process structure. Two old series of 250 tons/day of Jinchangyu Gold Mine, the rough selection of the first two-slot foam, the grade of up to 180 g / ton, greatly exceeding the qualified concentrate grade of 110 g / ton; the first section of Wulong Gold Mine Floating coarse selection of the first tank foam, the grade is up to 260 g / ton; the priority enrichment of Jiaojia Gold Mine can obtain qualified concentrate, its grade is 173 g / ton, the recovery rate of coarse selection of the first tank is 70-75% .

For some ores with low gold grade and low carrier minerals, the coarse foaming amount is small, resulting in low concentration of selected operations and failure to form a stable foam layer. In response, some concentrators have adopted a “concentrated selection” process. The flotation stage or two or more flotation series rough foams will be combined into a selection operation to stabilize the selection process. Wulong Gold Mine combines the roughing operation foam of 14m ³ large flotation machine in the two-stage grinding process into a selected circuit composed of 6A flotation machine for centralized selection, which improves the flotation effect.

The gold mines that use the flotation process in 1985 and their production processes are described below.

(1) Single flotation process. Such gold mines mainly include mines such as Suichang, Zhuji, Wenyu, Longshui, Yu'er Cliff and Hetai.

(2) Flotation-Cyanide process. This is the most used process in China's rock gold mines. Such mines include gold mines such as Jinchangyu, Zhaoyuan, Wulong, Xincheng, Jiaojia, Sanshan Island and Luoshan. Most of these mines use a flotation gold concentrate cyanidation process. A very small number of mines that use separate flotation are cyanidation of the separation flotation tailings, such as the Zhaoyuan Gold Mine.

For containing high levels of arsenic sulfide or carbonaceous gold ore containing iron ore and refractory gold, can be used flotation - roasting - cyanidation process flow. The gold-arsenic ore in Hunan Golden Cave is treated by this process. In 1958, the Hunan Institute of Metallurgy carried out a pilot study on the roasting and arsenic removal of arsenic-containing gold concentrates. In the early 1960s, the use of shaft furnace roasting was changed to tunnel kiln roasting after the 1970s due to sintering of the furnace material and deterioration of working conditions. It is also discontinued due to poor arsenic removal and unsatisfactory operation. Since 1975, after repeated trials, it has been decided to use a rotary kiln roasting program. In September 1978, a Φ0.6 (inside diameter) × 8.0 m rotary kiln was put into operation, and the kiln treated 7 tons of arsenic gold concentrate daily. The composition of arsenic gold concentrate is: As20%, S18%, Aul00 g/ton. After calcination, the arsenic contained in the calcine was reduced to less than 1%, and the arsenic removal rate was 98%. At the same time, in the roasting process, arsenic is recovered, and the by-product white peony (including AS2O2 ≥ 96%) is exported for sale, and the arsenic containing less than 1% of the cinnabar is sent to cyanide for gold extraction. The application of this process has brought a new life to the closed Golden Cave Gold Mine. In 1983, it was promoted in the roasting-cyanide process of the Karamay arsenic-bearing gold concentrate in Xinjiang, which improved the cyanidation recovery rate of gold by 10% and achieved remarkable results.

(3) Re-election - flotation process. See “Application of Gravity Dressing in Rock Gold Production” in this section.

(4) Mercury-flotation process. The gold mines using this process mainly include Jiapigou Gold Mine and Qinling Gold Mine Jindongyu Concentrator.

Most of the above process does not include local small and medium gold mines. Some mines are also planning to renovate existing processes (such as gold deposits such as Yu'er Cliff, Longshui, and Zhuji).

Second, the improvement of the pharmaceutical system

In the flotation process, in order to achieve the sorting effect, various flotation agents need to be added to the slurry. The most used flotation reagents in China's gold selection plants are: xanthate, black medicine, second oil, pine oil, lime, soda, sodium sulfide, copper sulfate, and the like. After years of production practice and scientific research, China has accumulated a lot of experience in seeking new flotation reagents, rational adjustment of flotation reagent systems and mixed use of pharmaceuticals, and has achieved beneficial results.

The focus of continuous improvement and improvement of the gold-selecting prescriptions is to find new collectors that have strong selectivity for gold minerals and have weak ability to capture sulfide minerals such as copper, lead , zinc , iron, etc. , and are effective for gold-containing oxidized ores. Collector. The selection of non-cyanide combination inhibitors for polymetallic gold-bearing ores has also received attention. In the large amount of work done, it is most effective to use a mixture of collectors.

Since the 1970s, many gold-exchange mills have tried a variety of flotation reagents based on their ore properties. In the early 1970s, Shandong Zhaoyuan and Luoshan two gold mines had tried Z-200 collector (sulfuramide) in production, which was characterized by strong selectivity to gold and copper and iron sulfide. The catching effect is weak. It is used for "copper-sulfur separation" flotation (that is, the separation of gold and iron) has obvious effect, and is later stopped due to high cost.

In the case of mixed drugs, as early as the 1960s, pharmaceuticals were mixed in non-ferrous metal concentrators, and since then, they have been applied and developed in gold mines.

In June 1972, the Jinchangyu Gold Mine used a mixture of butylammonium black and butylxanthate in a ratio of 1:2 to obtain significant technical and economic effects. The amount of butyl yellow was reduced by 66.7%. The total dosage of the two agents was reduced by 50% compared with the use of butyl xanthate alone, and the amount of the second oil was also reduced by 50%. The drastic reduction of the amount of flotation agent not only saves the cost of the agent, but also improves the drug removal operation before the cyanidation of the concentrate. As a result, the flotation recovery rate was increased by 1.43%. Since then, the combination of butylammonium black and butyl xanthate in various proportions has been promoted and applied in most rock gold concentrators. For example, in 1982, when the ratio of butyl xanthate and butylammonium black drug in a ratio of 1:2 was used in Zhejiang Tunchang Gold Mine Concentrator, the recovery rates of gold and silver were increased respectively. 7.11% and 10.52%, the grade of concentrate is also significantly improved. In 1975, Wulong Gold Mine used a mixture of isoamyl xanthate and butyl xanthate in a ratio of 1:3 in flotation operation. The concentrate grade increased by 18.20 g compared with butyl xanthate alone. / ton, the gold recovery rate increased by nearly 1%. In addition, it is also confirmed that the mixed base xanthate produced by Shenyang Beneficiation Pharmacy Plant, or the mixed base xanthate and butyl xanthate can be mixed in a ratio of 1:2, the recovery rate of gold can be compared with the single use of butyl xanthate. Increase by 0.77%.

Since its commissioning in 1978, Jiaojia Gold Mine has been processing primary sulfide ore. The ore dressing index is relatively good. The concentrate grade is above 130 g/ton and the recovery rate of gold is 94-95%. With the development of production, in order to make full use of mineral resources, it is necessary to treat oxidized ore about 30 meters from the surface. In 1981, it was treated a small amount, but the production index was not good. The flotation recovery rate was only 70%, so it was suspended. In 1983, the Northeast Institute of Technology and the Jiaojia Gold Mine cooperated to study the gold-bearing oxidized ore selection project and achieved good results: when the original ore grade was 4 g/t, the gold content was 136.41 g/t. Concentrate, gold recovery rate of up to 84.23%, and confirmed: mixed drugs can significantly improve the gold selection index.

Third, the development of flotation equipment

The flotation machine is the main equipment for completing the flotation process. There are many types of flotation machines. Generally, the flotation machine is divided into three types: mechanical agitating type (machine agitating type), pneumatic mechanical stirring type (air agitating type), and no mechanical stirring type (pressure type). The most used in China's gold concentrator is the machine-based flotation machine. In the 1970s, except for some old concentrators that used the Farinawald flotation machine, most of the concentrators basically used the XJK flotation machine.

The XJK flotation machine is a series of flotation equipment modified by the Chinese imitation of the Soviet Mihanobu type flotation machine. Its inflator consists of an impeller with radially arranged vanes and a cover plate with inclined guide vanes. The XJK flotation machine has the advantages of self-priming air and self-priming slurry, so it is easy to arrange on the same operating platform. The middle mine can return spontaneously, with simple structure, convenient operation and easy maintenance. Therefore, it is widely used in various types and scales of concentrators. The main disadvantage is that the amount of inflation is small, it is difficult to adjust, the energy consumption is large, and it is easy to wear.

In order to meet the needs of the development of gold beneficiation, the improvement of flotation equipment and the introduction of advanced new flotation machines were valued by the gold industry as early as the early 1970s. The Wulong Gold Mine replaced the XJK flotation machine with six Φ2200×7000 mm flotation columns in the rough selection and sweeping operations of flotation in June 1972.

The flotation column is a compressed air flotation machine without mechanical stirring device. It is composed of a circular or rectangular cylinder and an inflator. Its main advantages are simple structure, easy manufacture and maintenance, and low energy consumption. The main disadvantage is that the selection of the coarse and dense particles is poor due to no mechanical agitation; the aerator is easy to block, the consumption of the medicament is large; when parking, the ore must be mined, causing metal loss. Therefore, gold concentrators are rarely used in recent years.

Since the 1980s, with the expansion of the size of the concentrator, the large-scale flotation machine has become a worldwide development trend. In China's gold selection plant, the use of large-volume flotation machines has also taken a successful step. In July 1980, Wulong Gold Mine replaced the original flotation column with six domestic CHF-X14 gas-floating flotation machines. This air-floating flotation machine is more scientific and more reasonable in structure than the XJK flotation machine. Because of the combination of mechanically agitated pulp and externally pressed air, the impeller can work at low speeds. The utility model has the advantages that the slurry surface is stable, the coarse particles and the fine minerals are floated, the electric energy is saved, the mechanical wear is less, and the disadvantages of the XJK type are basically eliminated. The production practice of Wulong Gold Mine proves that the use of CHF-X14 flotation machine can improve the recovery rate of gold, reduce the dosage of chemicals and reduce mechanical wear. In January 1984, the Jinchangyu Gold Mine Concentrator installed 10 4m3 air-crushing flotation machines in its expanded 500-ton/day new system for rough selection and sweeping operations of flotation.

Due to the limitation of the scale of the mine, the large-scale equipment is unlikely to become the only mode for the development of flotation equipment in China's rock gold mines. According to the characteristics of China's gold production, the development and adoption of various types and specifications, high efficiency and energy saving new flotation machine is underway.

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