Separation process of a rotary kiln in Shilu Copper Mine

According to the different material processing methods in the roasting stage, the segregation method is divided into two types: “one-stage segregation” and “two-stage segregation”. A piece of segregation method is to mix ore, salt and reducing agent into the roaster (mostly using horizontal rotary kiln), and heating and segregation of materials are carried out in the same EQUIPMENT. The two-stage segregation method, also known as the "Torco" method, first preheats the ore to the reaction temperature, and then mixes the appropriate amount of salt and reducing agent into the segregation reactor for isolation. Current production shows that both segregation methods can achieve higher segregation indicators.
Shilutongkuang period of segregation process kiln
China's Guangdong Shilu copper mine is a deep-oxidation refractory copper ore with a copper grade of 1.3 to 2.5%. Since 1964, the relevant scientific research and design units have been compared in various schemes. The separation-flotation method has the advantages of simple process, high grade of concentrate and high recovery rate. It was designed in 1966 and put into trial production in 1970.
The direct selection of refractory copper oxide ore is a new process. There is no practical experience in foreign countries. At the initial stage of production, many problems were encountered, such as low processing capacity, abnormal equipment operation, low concentrate grade and recovery rate, and very unstable production. After several years of hard work and repeated improvement, the key to the separation process and equipment of the direct heating rotary kiln was basically solved, and a good separation effect was obtained initially, which basically reached the level of production.
1 ore properties
The mine belongs to the quartz diorite porphyry and the limestone limestone in contact with the skarn copper deposit. The ore is earthy and has a deep oxidation. Due to the secondary enrichment in the diagenetic stage, the copper liquid and the oxides of silicon, iron and aluminum form a combined copper oxide during the diffusion process of the copper liquid, covering the surface and sandwiching the malachite type ore. The copper-bearing minerals are mainly malachite, with a small amount of blue copper ore, chrysocolla and water cholesterium. Iron ore is mainly limonite, followed by magnetite and iron ore. In addition to iron clay , gangues include quartz, mica , garnet , amphibole, serpentine, chlorite and calcite . The content of iron clay in the ore is very high, -200 mesh is as high as 48%, ore is 27.1%, and the ore is about 300 mm. The original mineral composition is listed in the next two tables. [next]

The ore is seriously polluted by fine mud, and the copper binding rate is high. Generally speaking, the high ore grade is combined with the corresponding increase of copper. According to the results of phase analysis, combined copper accounts for 5-40% of total copper, free copper oxide accounts for 50-80%, and copper sulfide accounts for 9-20%. [next]
2 Segregation-flotation process In the flotation process (figure 1 and Figure 2 below), the solid line indicates the process used before March 1975, and the flotation machine can select more than 40% of the concentrate grade.

Separation system main equipment schematic
1—combustion chamber; 2—stainless steel radial heat exchanger; 3—common steel honeycomb heat exchanger;
4—single tube vortex dust collector; 5—multiple tube vortex dust collector; 6—exhaust fan; 7—tilting dust collection cooling tower;
8—water film dust collector; 9—plastic chimney; 10—sealed disc feeder; 11—belt scale
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Segregation - flotation process
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The size of the isolated shovel is: 3.6 meters in diameter and 50 meters in length. The barrel part of the cylinder will be (2 meters), which is a 20 mm thick heat-resistant stainless steel plate, and the rest is made of 22-28 mm thick 18MnCu steel plate. Pit lining of 200 mm (the low temperature section 150 millimeters) thick alumina brick, and 15.2 m in the metallic heat exchanger 6 m from the pit along the trailing head Fangxiang An pit, pit inclination of 3%, with pit The JZS 101 three-phase asynchronous commutator variable speed motor (N=15-25 kW, n=1050-350 rev/min) is driven by an auxiliary drive system with standby power supply. Under normal conditions, the 窖 speed is 1.48- 0.493 rpm.
3 Segregation-Flotation process parameters and results Separation technical conditions: raw ore containing copper grade 2-3%, particle size -4 mm, moisture about 5%, additive ratio: coal 3.5-4%, salt 1.8-2%. Separation temperature: heavy oil combustion flue gas inlet temperature is 1150-1250 °C; steam head temperature is 880-950 °C, and the isolated turning speed is 0.66-0.75% rpm.
Grinding and floating technical conditions: grinding overflow fineness 75-80%-200 mesh, grading concentration 30%, flotation concentration 24-28%, Dinghuang drug 1.2 kg / ton, 25 # black drug 0.15 kg / ton, 2 #æ²¹0.5 kg / ton, water glass 0.1 kg / ton.
Segregation - Flotation results:
Separation and enthalpy treatment volume 19.36 tons of dry ore/set time Burning rate (heavy oil) 4%
Smoke rate 25.68%
Two-stage dry dust collection rate 86.99%
Two-stage wet dust collection rate 98.39%
Recovery rate of volatile copper chloride 72.71%
Wet dust contains copper and water soluble copper loss 3.8%
Isolation kiln operation rate 70%
Concentrate grade (one selection of flotation column) more than 25% tailings grade 0.5-0.7%
Segregation - flotation yield 77% or so [next]
4 Main measures to solve the problems of separation process and equipment A. In order to meet the requirements of segregation in the thermal system, it is necessary to have suitable separation temperature and maintain the atmosphere suitable for segregation in the kiln (neutral or weak) Reducing).
B. In order to improve the burning conditions of heavy oil and avoid the burning of the flame into the kiln to cause sintering of the charge, the combustion chamber was reformed.
a. The volume of the combustion chamber is increased from 22 m ³ to 33 m ³ to reduce the spatial thermal strength.
b. Change the nozzle position from the original front to the side to extend the flame path.
c. Change the single nozzle (1000 kg/ton) to multiple nozzles (4*25 kg/ton).
C. The kiln head is replaced with a 2 m heat-resistant stainless steel cylinder, which is connected by a glass cloth telescopically connected movable grinding block, and a water-free cooling sealing device.
D. Exhaust fans with a volume of 105 m ³ /h and a pressure of 9810 Pa (103 mm water column).
E. In order to solve the anti-corrosion problem, the 1# kiln dust collecting cooling tower flue gas inlet short pipe and the lower part of the tower are all lined with epoxy resin lining graphite plate, and the 3# kiln is made of granite and epoxy resin mortar. turbulent collecting tower, titanium and graphite plate substrate inlet short tube.
F. In order to simplify the dust collection system and improve the operating conditions, the dry dust collection equipment is increased by 10 meters, and the dry dust is automatically returned to the kiln. At the same time, the separation batching and feeding were all modified to the disc feeder, and a self-made belt scale and necessary measuring instruments were installed.
G. Reconstruction of pulverized coal system, using chain mill to crush, wind-grading production of coal for separation, to solve the problem of insufficient coal production, poor quality, mixed coal in coal, coal blending in mine.

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