Practice of ore dressing of old plant cassiterite polyoxosulfur

The old factory mesh ore beneficiation plant is cloud tin Group Mining Development Co., Ltd. 1300t of daily processing plant re-election. Since its commissioning in 1992, the plant has been mainly engaged in the treatment of oxidized vein tin ore, divided into one or two systems, using three-stage grinding, three-stage sorting, secondary concentrate re-washing, and overflow treatment. Process flow. In recent years, with the change of resources ore, sand tin resources gradually disappeared, and then there is a higher Refractory iron-containing tin, iron, arsenic, copper, cassiterite symbiosis plurality of metal oxide mixed mineral sulfur, Residue mine, slag mine, etc. In order to adapt to the changes in the nature of the ore, the plant has carried out a series of practical explorations in the preparation of raw ore, improvement of process flow, application of new equipment, etc. At present, the main ore dressing indicators have reached a good level of similar mineral processing plants. Among them, the grade of tin coarse concentrate is 18% to 19%, and the tin recovery rate is 75% to 79%. In the production practice, we have mastered the characteristics of some cassite polymetallic oxygen-sulfur mixed ore beneficiation, and explored some new ways in improving the process flow, and obtained some experience in the technical management of this type of concentrator.

First, the nature of the ore

The ore has the following characteristics:

1. Containing tin, copper, arsenic and iron, it belongs to the oxygen-sulfur mixed ore of cassite polymetallic symbiosis with high economic value.

Table 1 Raw ore spectral analysis results

Table 2 Results of multi-element chemical analysis of ore

Table 3 Raw ore particle size analysis results

Table 4 Tin phase analysis results

2. The size of the cassiterite crystal is fine, and the dissociation degree of the monomer is poor. When the ore is broken to -1.2mm, there are 36.59% of the cassite inclusions, and it is closely symbiotic with pyrite, pyrrhotite, limonite, arsenopyrite, mica , calcite , quartz , fluorite, etc. Wrapped and semi-wrapped state is a difficult choice of tin ore.

Second, the production process and its characteristics

The ore mine adopts three-stage open-cut crushing ore and one-stage grinding process. The tin re-election adopts three-stage grinding, three-stage shaker sorting, secondary concentrate centralized re-washing and overflow separate treatment process; and desulfurization recovers copper-sulfur metal. A rough selection, a single sweep, and three selected mixed flotation processes are used. The production principle process is shown in the figure below.

Mineral processing principle flow chart

(1) Using high-efficiency crushing equipment, reforming the preparation process of raw ore, implementing multi-grinding and grinding, and processing the Dadshan mesh mine by the original design of the crushing mill mesh ore dressing plant. Before the selection, there is a complex crushing system and heavy medium removal. Waste system. After 1992, the concentrator was transformed into a re-election plant that now processes cassite polymetallic oxygen-sulfur mixed ore, residue ore, slag ore, etc., with a production scale of 1300t per day.

The raw ore preparation work of the plant was originally carried out by a PEF jaw crusher with one coarse crushing, two fine crushing, and three medium 1500mm×3000mm rod mills as a grinding process. The problem is that the final product size of the ore crushing is coarse, and the yield of +80mm accounts for 10%, which leads to a coarse grinding mill with a coarse grain size, low processing capacity, low technical efficiency of the grinding machine, and no grinding and over-grinding. Technical transformation of the preparation process is imperative.

Due to the high efficiency of the mined ore and the low efficiency of grinding, as the crushing of the ore before the beneficiation, the task of increasing the crushing task and reducing the low efficiency is the technical essence of implementing multiple crushing and grinding, and grinding. On the basis of sufficient argumentation, the basic plan for determining technological transformation is to replace the two PEF250mm×400mm and one PEF150mm×750mm jaw crusher with the world-class Nordberg GPl00 cone crusher. Superior technical performance to ensure product granularity. In March 2004, it invested more than 900,000 yuan to install a Nordberg GP100M cone crusher as a medium crushing device. In January 2007, it invested in the installation of a Nordberg GP100MF cone crusher as a fine crushing device.

Nordberg GP100 series cone crusher has the following characteristics: 1. Simple structure, reliable performance, convenient adjustment and maintenance, uniform product size and low loss of lining; 2. High processing capacity, high crushing efficiency, can be filled with ore , full cavity broken; 3, equipment running smoothly, low noise. The technical parameters of Nordberg GP100MF cone crusher are shown in Table 5.

Table 5 Nordberg GP100MF cone crusher technical parameters

In order to ensure the quality of the ore crusher, including controlling the maximum particle size, reducing the amount of sludge and eliminating debris. The specific transformation plan is as follows: 1. Maintain the screening and washing operation before the crushing machine, reduce the mud content of the crusher to the mine, create conditions for smooth discharge and reduce dust; 2. Keep the PEF250mm×400mm jaw crusher as the second. Secondary crushing ore, the ore-mining particle size is controlled below 85mm; 3. The ZDSM1555 single-layer linear vibrating strip screen is changed to double layer, the upper layer screen is 50mm apart, and the lower layer is 22mm with eye screen. The product on the upper layer sieve enters the PEF250mm×400mm jaw crusher, and the lower layer has the sieve on the eye screen to enter the GP100M cone crusher. 4. Adhere to the use of electromagnetic iron removal device on the belt conveyor to reduce the malfunction caused by foreign objects.

Table 6 Particle size composition of residue ore after treatment

After the transformation of the ore preparation system, the final product size of the crushed ore is reduced from 35 ram to 25 mm, achieving multiple crushing and grinding, crushing and grinding, and fine grinding into the grinding. Due to the reduction of the grinding grain size of a grinding person, the grinding treatment capacity is expanded. On January 23, 2007, the actual production process was investigated. The total processing capacity of the two mills was increased from 44.12 t/h to 51.00 t/11, and the capacity for treating oxidizing ore was increased by 15.6%. Grinding product particle size -1.2mm reached 92.74%, mill technical efficiency reached 79.87%, the crushing system transformation achieved good results.

(2) Tossing waste before election. Improve the selected grade

When the plant is dealing with residual ore, slag ore and cassite polymetallic oxygen-sulfur mixed ore, the pre-selection of ore is a significant problem due to the high mining depletion rate of such ore. We consider the combination of vibrating screen and hand selection to discard large amounts of monomer waste rock as early as possible. After the adjustment of the crushing process was completed in March 2006, the shape and size of the screen hole were changed by a linear vibrating screen, and the spacing of the upper screen of the vibrating screen was set to 50 mm wide. The material on the screen was combined with the hand-selected process to treat the low-grade ore. Carry out a lot of waste. From January to October 2006, a total of 455 tons of residual ore was supplied to the pit. Through the abandonment measures, the candidate grade increased from 0.15% to 0.34%, and the rejection rate reached 36%. The amount of enrollment is processed by 1000t per day, and increased to 1400t per day. Production practice shows that this is an effective way to save the mine and reduce the cost of mineral processing.

(III) Application of flotation desulfurization and desulfurization process

Due to the diversity of the treated minerals, the screening process is also aimed at dealing with the variability of the minerals, adopting a strategy of changing to the opposite direction, and adopting the pure re-election process in the treatment of oxidized ore, residue ore and slag ore. In the treatment of cassite polymetallic symbiotic oxygen-sulfur mixed ore, flotation-re-election production process is adopted. First, flotation is used to remove sulfide impurities, and the effect of sulfide on re-election of cassiterite is reduced, and then cloud is used. The traditional stage of tin grinding, phase selection and re-election process to recover tin metal. In June 2001, the net selection plant began to adopt the flotation de-mixing process. The production practice in the past few years has shown that the effect of flotation de-mixing directly affects the effect of re-election of cassiterite. Since the plant used to be a pure re-election process, the ore preparation was selected to have a coarser particle size, so the flotation de-mixing effect was less than ideal. However, it is difficult to change the granularity of candidates. First, the grinding capacity is not enough. Second, the plant conditions are limited. In addition, the plant mainly selects tin, and the copper metal is recovered from the defoamed foam. Due to the brittleness of the cassiterite, in order to avoid the excessive crushing of the cassiterite and affect the recovery of tin, it is not suitable for fine grinding. The process of removing sulfur from the process is a service for tin selection. The quality of flotation and decontamination has an important impact on improving the recovery rate of tin.

The flotation of the flotation plant in the net selection plant accounts for 19% to 25% of the ore yield and the tin loss rate is less than 4%. By flotation de-mixing, the original ore tin grade is from 0.744%. 1.385% increased to 0.886% to 1.772%. Due to the removal of large-density sulfide impurities, the end of the shaker concentrate is distinct, and the tin concentrate is easy to handle, which creates favorable conditions for the effective recovery of tin metal.

(IV) Improvement of the process of re-washing system

The re-washing system is the process of centralized sorting of secondary concentrates in each section of the sand mine system. Before 2006, the plant used a pre-rewashing of the secondary concentrates of each section of the bed, and a grinding and re-selection of the grinding and re-selection of the secondary ore. From January to June 2006, according to the problems in production, the process of the re-washing system was improved to: the pre-rewashing of the concentrated concentrates in each section of the bed, the pre-rewashing of the ore after grinding, and then entering a re-washing, one re-washing After the mine is reground, it is re-washed twice. The process was transformed into two grinding and three sorting processes. After the transformation, the comprehensive recovery rate of tin in the re-washing system increased from 14.97% before the transformation to 16.77% after the transformation, which increased by 1.8%, and the annual economic benefit was 1.24 million yuan.

Since June 2006, due to the high content of impurities in the oxygen-sulfur mixed ore mixed with cassiterite, tin and iron, sulfur, arsenic and other impurities are densely symbiotic, the size of the inlay is fine, the density of several minerals is close, and the density difference is small. Therefore, the shaker is difficult to sort. In addition, due to the coarse grain size of each bed, the large number of detached nectars without dissociation are enriched in the secondary concentrate re-washing system, and the high-impurity feed is again formed in the re-washing system, which greatly affects the re-washing system. Product quality and ore recovery rate. Therefore, the plant once again improved the re-washing system process: the concentrates in each section were concentrated into the grinding, after the grinding, the flotation was removed, and the pre-repairing of the pre-bed was carried out. bed. A new process of flotation-re-election, two-stage grinding and two shaker sorting is formed. The process aims to reduce the influence of sulfide on the sorting of the rewashing system, and at the same time, recover the valuable copper metal in the defoamed foam, so that the resources can be fully recycled, and the product quality and the recovery rate of the re-washing system can be improved. purpose.

Comparison of production statistics before and after the transformation: the grade of tin coarse concentrate in the re-washing system before transformation was 16.09%, the recovery rate was 15.87%, and the grade of coarse concentrate after transformation was 16.84%, and the recovery rate was 17.15%. Through technological transformation, not only the tin recovery rate has increased by 1.28%, but also the quality of tin products has been improved. The annual economic benefit is 850,000 yuan.

(5) Application of high frequency vibration fine screen

A section of the mesh mining plant selection workshop is a 1500mm×3000mm ball mill and a spiral classifier closed-circuit grinding. Because the spiral classifier is classified according to the sedimentation speed of the ore in the medium water, on the one hand, the classification efficiency is low, the granularity of the flotation decontamination operation is coarse, and the flotation is not completely eliminated. The flotation machine sinks and is forced to open frequently. The bottom of the tank accident gate valve puts coarse sand, which affects the production; on the other hand, some fine-grain monomer cassiterite is re-grinded and formed. Considering that the sieving is classified according to the particle size of the material, the plant introduced HGZS high-frequency vibrating fine screen combined with a spiral classifier in January 2007 to form a closed circuit with a section of grinding, as a pre-screening and inspection of a section of grinding. Screening. The high-frequency vibrating fine screen has the characteristics of large processing capacity, high screening efficiency, low energy consumption, reliable operation, light weight, convenient operation and maintenance, and the like. According to the production inspection on February 8, 2007, the high-frequency vibrating fine screening efficiency was 90.35%.

(6) Recovery of copper in desulfurized sulfide

After the desulfurized sulfide is ground, a rough selection, a single sweep, and three selective flotation processes are used. The three minerals of copper, sulfur and arsenic in the cassite polymetallic oxygen-sulfur mixed ore have strong activity, and the floatability is quite good, and the separation of copper and sulfur is difficult. According to the conventional pharmaceutical system, it is difficult to effectively suppress sulfur and arsenic impurities. In the separation of copper and sulfur, the amount of CaO is the key factor for the whole separation flotation. The addition of CaO must reach 14kg/t to effectively suppress the sulfur and arsenic impurities. When the amount of CaO is 8kg/t, the arsenic grade in copper concentrate is 5.18%, and the arsenic mixing rate is 91.92%. After the amount of CaO increased to 14kg/t, the arsenic content in the copper concentrate decreased to 1.537%, and the arsenic mixing rate dropped to 9.16%.

Third, the conclusion

After years of production practice, the reticulated ore dressing plant has mastered the technical key to the treatment of polythene oxide mixed ore in the tin-stone:

1. Dissociation is the premise of tin selection. Since the useful minerals in the cassite polymetallic oxygen-sulfur mixed ore are mostly dense symbiosis, if the cassiterite is not dissociated from the ore, the tin can not be selected, so it must be fully crushed and ground before selection. The principle to be followed in grinding is to achieve sufficient monomer dissociation of the cassiterite and to avoid over-grinding. The production practice experience is “stage grinding, stage selection”, try to achieve “the early harvest, the loss will be lost early”.

2, the removal of sulfide impurities is the key to tin selection. Since such ore contains a large amount of sulfide and its density is large, it cannot be removed by single re-election. Therefore, flotation desulfurization must be carried out before or after re-election to obtain a good quality tin concentrate and higher. Tin recovery rate. The principle of flotation desulfurization should be: the sulphide should be floated as much as possible, and the loss of tin in sulphide should be minimized. To this end, it is necessary to reasonably grasp the fineness of grinding, the concentration of flotation, the pH of the slurry, and the accurate addition of various flotation reagents.

3. The flotation of copper and sulfur in the desulfurized sulfides must be carried out using a high alkali process. The amount of lime must be 14 kg/t and the pH should be above 11. Lime is the most significant factor in the separation of copper and sulfur flotation agents. The tin ore multi-metal oxygen-sulfur mixed ore is difficult to be used for mineral processing. In the future, it is also necessary to explore new ways to do the recovery of fine-grained cassiterite, associated copper metal and separation of sulfur and arsenic, continuously improve the beneficiation process and make limited mine resources. Get fully and effectively recycled.

references

1. Ma Zhengtang. Reduce the particle size of crushed products and improve the efficiency of grinding production [J]. Non-ferrous metals: mineral processing, 2005 (6): 28-32.

2. Tin dressing preparation group. Tin beneficiation [M]. Beijing: Metallurgical Industry Press, 1978: 86-87.

3, Duan Xixiang. Crushed mine and grinding [M]. 2 edition. Beijing: Metallurgical Industry Press. 2006: 114-115.

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