I. Overview
Longtoushan gold mine tailings filter press facility in March 2003 completed and put into production. From the overall production situation, after the gradual commissioning is normal, the sewage treatment cost is saved, the return of the filtrate reduces the consumption of the NaCN agent, and the recovered gold is recovered. The transportation cost of the filter tailings is deducted, and a certain economy is obtained. benefit. Due to the special suburban location of the mine and the need to stabilize the production and operation in order to protect the surrounding environment, the tailings filter dry reactor system cannot be used during the rainy season. According to the experience gained in the production practice, the tailings pressure filter-filter cake is treated by alkaline chlorination and then sent to the tailings dam, which avoids the danger of the filter biscuits being washed away by the rainstorm in the rainy season. It can also save the cost of sewage treatment and NaCN, reduce production costs and increase economic benefits. Production practice shows that, under the existing circumstances, less reform funds are invested, combined with the original facilities in the past, to form a new tailings treatment method, that is, it is reasonable to use tailings pressure filtration-filter cake to purify and purify in the rainy season. And feasible.
Second, tailings pressure filtration transport transformation
(1) Process flow and main technical indicators
1. The process flow of tailings pressure filtration-filter cake mixing treatment is shown in Figure 1.
2, the main technical indicators
Design processing capacity 400~450t/d
Ore density 2.65~2.70t/m 3
Tailings slurry concentration 45% to 50%
Slurry discharge flow 25~30m 3 /h
Water content of filter cake after pressure filtration ≤23%
Filter cake plus new water after slurry concentration 45%
Filter cake plus fresh water after slurry pH 11.0
CN - mass concentration after filter cake adjustment 100~200mg/L
CN - mass concentration <0.5mg/L after pulping treatment
Filter press single cycle time 40min
Filter press working pressure 0.8MPa
Sewage purification reaction time 1.5h
C1 2 dosage 2.0kg/t (1.652kg/m 3 )
3. Process flow. The plant discharges 45%-50% of the slurry from the tailings buffer tank of the sewage plant, and then presses it into the filter press chamber by the feed pump, and discharges the water by pressure filtration to form a filter cake with a water content of less than 23%. After that, the pressure filtration ends. The cyanide-containing filter press solution enters the return water tank and then returns to the plant for reuse; the filter cake after pressure filtration is discharged into the buffer chute (adding fresh water) through the belt conveyor, and is transferred into a spiral stirring tank to adjust the concentration to 40% to 45%. It flows into the newly added agitation tank and then flows into the original wet sewage treatment plant evenly. After the purification treatment reaches the standard, it is sent to the tailings pond.
(2) Major equipment
1, One set of 1200 conical spiral agitation tank (self-made, see Figure 2).
2, add One set of 3200×3300 mixing tank.
3. The production and configuration of the slurry chute and slurry pipeline are carried out according to the site conditions.
Third, investment
The total cost of the renovation project is 85,000 yuan; including equipment purchase, equipment production, installation engineering and other costs, as shown in Table 1.
Table 1 Total investment in renovation costs
project name | Amount / 10,000 yuan | % of total investment /% | Remarks |
Equipment purchase and transportation fees Facility material purchase and transportation fees Installation and production costs Other fees total | 0.70 6.00 1.00 0.80 8.50 | 8.24 70.59 11.76 9.41 100 | Conical spiral mixing tank and new mixing tank reducer Chute and pipeline platform, etc. Equipment foundation |
Fourth, technical and economic evaluation
The tailings pressure filter-filter cake is used to purify and discharge the solution to the tailings pond. Although it has increased the processing procedure compared with any previous treatment method, it can save the main pharmaceutical consumption and recover more gold and reduce the production cost. Increase economic efficiency. From July 2003 to July 2004 (the ore properties are similar), the NaCN consumption and sewage treatment cost of the selected plants in different periods are shown in Table 2; the cost of tailings pressure filtration-filter cake pulping purification treatment is shown in Table 3; The results are shown in Table 4; the added cost of the new process is shown in Table 5.
Table 2 NaCN consumption and sewage treatment costs of selected plants from July 2003 to July 2004
time | NaCN Unit consumption / (kg·t -1 ) | Cl 2 Unit consumption / (kg·t -1 ) | Pressure filtration cost/ (yuan·t -1 ) | Sewage purification Processing cost / (yuan·t -1 ) | Pressure filtration + sewage Purification cost / (yuan·t -1 ) | Remarks |
Traditional wet discharge period from July to October 2003 | 1.14 | 5.60 | 1.63 | 18.86 | 20.49 | Maintenance costs of the filter press still need to occur during conventional wet treatment discharges |
Pressure filtration - dry discharge period from November 2003 to January 2004 | 0.80 | 0.86 | 10.39 | 4.15 | 14.54 | Sewage purification costs still need to occur during filter-dry discharge |
From May to July 2004, tailings pressure filtration-filter cake was purified during pulping | 0.93 | 4.59 | 7.89 | 7.59 | 15.48 | The cost data of filter press purification operation is the accumulated index in June and July. In order to ensure the discharge of sewage, the purification operation will increase the dosage of Cl 2 by 30%. |
Table 3 tailings pressure filtration - filter cake pulping purification treatment costs
project name | Consumption | unit price | Amount / (yuan·t -1 ) | Remarks |
Labor fee Electricity fee Cl 2 Filter cloth CaO Other (including maintenance) total | 25 people 5.5kW·h/t 2.5kg/t 4.0kg/t | 1000 yuan / month 0.50 yuan / (kW · h) 2.5 yuan / t 180 yuan / t | 2.27 2.75 6.25 1.50 0.72 1.00 14.49 | Annual processing of ore 110000t with reference to actual production situation |
Table 4 Results of main increase and decrease calculation
project name | Consumption | unit price | According to the half-year treatment of 55,000 tons of ore, the added benefit is calculated/10,000 yuan | Remarks |
Save Cl 2 Save NaCN Save CaO Prolific gold total | 2.20kg/t 0.15kg/t 3.00kg/t 0.015g/m 3 | 2.5 yuan / kg 15.0 yuan / kg 0.18 yuan / kg 100 yuan / g | 30.25 12.38 2.97 7.64 53.24 | Calculated by pressure filtration to the mine concentration of 45% |
Table 5 Increased costs of new operations
project name | Consumption (new) | unit price | Amount / (yuan·t -1 ) | Remarks |
Labor fee Electricity fee Cl 2 CaO Other (including maintenance) total | 4 people 2.5kW·h/t 1.5kg/t 1.0kg/t | 1000 yuan / month 0.50 yuan / (kW · h) 2.5 yuan / t 180 yuan / t | 0.44 1.25 3.75 0.18 0.20 5.82 | Calculate 110000t in years Refer to the actual production situation According to the calculation of 55,000 tons of ore for half a year, the added cost is 321,100 yuan. |
It can be seen from the calculation of the main increase and decrease (see Table 4) and the cost increase of the newly added process (see Table 5). It can be seen that the investment of 85,000 yuan to implement the tailings treatment process transformation can be used in the rainy season with tailings pressure filtration-filter cake adjustment. The pulp purification treatment process can create economic benefits of 21.23 million yuan.
V. Conclusion
(1) The total cost of the renovation project is 85,000 yuan, which is a project with less investment, relatively quick return and good economic benefits. The project has been completed and the equipment is operating normally and the process is smooth. The savings of NaCN and Cl 2 , which are the main materials consumed in production, have achieved the desired results.
(2) Due to the first pressure filtration, most of the cyanide-containing wastewater is recycled, and the filter cake is added with fresh water for slurrying into the wet sewage treatment system. The total cyanide mass concentration is reduced from the original 350 mg/L to 100 mg/ L or so not only greatly reduces the sewage treatment costs, but also facilitates the discharge of national standards after sewage treatment.
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