(A) Overview Hengdong Hengdong lead zinc mine in Hunan province, there is highway, convenient transportation.
The mine set up in 1965, high-grade ore mined by hand, manual wash bucket, to May 1973 were provided to the national lead and zinc metal volume over 7000 tons, 90,000 tons of fluorite ore, 3.06 million yuan turned over to profit.
In order to make rational use of national resources, improve working conditions, and increase labor productivity, the mine self-raised funds of 650,000 yuan, started construction in June 1972, and built a 200-ton/day flotation plant in ten months. When the production of lead and zinc metal more than one thousand tons, profit remittances 410,000 yuan (accounting for 64% of the beneficiation plant investment).
The mine is developed by Pingyi, a blind inclined well, and shallow hole mining method. The Pingyukou to the ore dressing plant is about 350 meters. The original mine is pulled by the diesel locomotive to the original ore warehouse of the ore dressing plant and is manually unloaded.
Power supply: The power supply of the concentrator is sent to the effluent substation of the concentrator by a single circuit of 10 kV in the 10 km southeast of the mining area, and is sent to each section in 380 volts.
Water: water for use in mineral processing plant pit water, gravity concentrator to 150 m 3 high pool.
Tailings: It flows through a 205-meter inverted siphon and a 1200-meter open channel to the tailings pond, with a volume of 2 million m3.
(two) process
1. Properties of raw ore There are two production areas in the mine, all of which are vein deposits produced in metamorphic rocks. Punch working area mine to produce silver-based fluorite. By-product lead and zinc. After the ore was selected, the fluorite lump mine was directly exported, and the lead-zinc lump ore was transported to the concentrator for treatment. The Shiyan Chonggong District is mainly produced by lead and zinc. The grade of fluorite is low and the hand selection is difficult. The ore dressing plant mainly deals with the ore of No. 2 vein in Shiyan Chonggong District. The No. 2 vein is a metamorphic rock and igneous vein-like lead-zinc polymetallic deposit. The main metallic minerals galena, sphalerite, a small amount of brass and pyrite ore. The gangue minerals are quartz , fluorite, and the like. The ore contains 3% lead, 3% zinc, and calcium fluoride greater than 10%. The water content and oxidation rate are not high, and it is easy to select ore for coarse grain inlay (the southern end of No. 2 vein, some ore is deeply oxidized, and there is no mining at present).
2. Process Flow Broken into two sections and one closed circuit, the ore size is 220 mm, and the final product size is 25~0 mm. The upper part of the original mine silo is equipped with a fixed grid sieve, and the ore is larger than 220 mm ore.
Ore grinding to -200 mesh accounts for about 50%, and lead and zinc are preferentially floated. The lead selection process is one rough selection, one sweep selection, two selections, and one finish sweep. The zinc selection process is a rough selection, a sweep selection, and a second selection. The lead and zinc coarse sweeping selections all use flotation columns, and the flotation machines are selected. Fluorite is not currently recycled. The process flow and technical conditions are shown in Figure 1 below.
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Dehydration of lead and zinc concentrates, currently using natural sedimentation and soil oven drying. The labor force is high and the working conditions are extremely poor. The mine is trying to use mechanical dewatering.
(III) Main equipment of the concentrator (below)
(4) Others 1. The site selection of the concentrator has the following characteristics:
(1) The original ore transportation distance is short. The concentrator is about 350 meters away from the main level, and the heavy truck goes downhill.
(2) The construction of a hillside wasteland does not occupy farmland, nor does it hinder the construction of farmland water conservancy.
(3) Make full use of the land type to achieve self-flow of slurry in the plant, self-flow of tailings, and self-flow of water outside the plant. The concentrator has no pumping equipment, which saves production costs.
2. The equipment configuration is compact, especially all flotation columns are arranged at the same level, and the medium mine returns to use the lifting tank and compressed air instead of the sand pump. Saves height differences and facilitates operational management. The total sectional area of four flotation column 4 × 1.82 = 7.28 m, the slurry comprising the total air consumption of lift of 18 m / min, inlet air pressure of 1.5 kg / cm 2. Flotation Machine - Stirring Tank - The relationship between the height difference of the flotation column is shown in Figure 2 below.
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3. The tailings conveying adopts the inverted siphon and the open channel self-flow conveying, as shown in Figure 3 below.
The diameter of the siphon pipe is Ф100 mm. It passes over a valley with a twist of 205 meters. The entrance elevation is 197.5 meters, the exit elevation is 185 meters, and the lowest elevation of the pipe is about 155 meters. The open channel is 1200 meters long, rectangular section, width × height = 120 × 250 mm, slope 4%, open channel is brick, external cement mortar.
The production system is basically successful through production certification, but it also exists:
(1) The volume of the inlet buffer tank is too small. When the amount of flotation tailings changes greatly, the slurry overflows.
(2) The inferior section of the inverted siphon wears faster, and the tube needs to be turned over after about half a year.
4. The apparatus system pressure air flotation column using 120 rural waste gas type coal conversion machine. Each air volume is about 6 m 3 /min, and the outlet wind pressure is 2 kg / cm 2 . The machine is a single cylinder, with simple structure and convenient maintenance. There is a problem in use. The spring piece is made of 40 gauge ordinary round steel car, which has low strength and is easy to be damaged, and needs to be replaced frequently.
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