Treatment of gold-arsenic raw materials and environmental protection issues (2)

In order to recover gold from the slag, the slag containing 0.1 to 0.3% arsenic should be sent to the pyrometallurgical or hydrometallurgical section and treated by known methods. The direct cyanidation of the calcined slag after vacuum heat treatment only results in a high gold recovery from the low- iron , carbon-free material. For most concentrates, the acid-treated residue should be subjected to a combined acid treatment to leach the iron compound prior to cyanidation. When the residue contains carbonaceous rock sheets, oxidative roasting should be performed to remove carbon. According to this scheme, even if it is difficult to treat concentrates like gold-arsenic carbon concentrate, the gold recovery rate can reach 97 to 98%. The easiest way to do this is to smelt the slag with the charge from a copper smelter or a lead smelter.
The method of selecting a reasonable method for recovering gold from the residue after vacuum heat treatment requires various compositions according to various specific conditions (for example, whether or not non-ferrous metals, carbonaceous shale and iron sulfides are present in the raw materials), and fineness. The characteristics of the mining area (distance from the fire smelter and whether there is industrial water) are solved.
For all gold-arsenic concentrates, removing arsenic from concentrates in advance is the common and most complex process.
In order to realize the vacuum heat treatment of the bulk material, the Institute of Metallurgy and Mineral Processing of the Kazakh Soviet Socialist Republic Institute, together with the National Institute of Rare Metals and the Central Asian Nonferrous Metal Design Institute, developed a vacuum vibration equipment for continuous operation. The main body of such a device is a vertical closed heating vibration transporter. Expanded semi-industrial test results have shown that this equipment has a working capacity of 700 ° C when used for a long time. These devices are currently being retrofitted to increase processing power and improve product quality. In the vibrator, the material dummy layer formed by the directional vibration has high heat exchange and mass exchange (the thermal conductivity in the vibration layer is 15-20 times of the thermal conductivity in the fixed layer), thereby enabling the device Maintain a high unit handling capacity of 5 to 7 tons / m 2 evaporation surface every day and night.
When the gold-arsenic concentrate of a mining area in Kazakhstan was subjected to vacuum heat treatment and arsenic semi-industrial test, the equipment used was an industrial vibration vacuum heat treatment device, which has a processing capacity of 5 tons per day and night. The test results prove that the main indicators of the whole heat treatment process are correct and reliable.
At a temperature of 650 ~ 670 ℃, residual pressure from 30 to 50 mm under conditions • mercury column, after 5-7 minutes in a vacuum heat treatment, As 6.2% from containing, SiO 2 24%. Al 2 O 3 8.8%, Fel 6.55%, Au 80.7 g / ton concentrate in the arsenic of 95~97% (including arsenic in the slag is 0.2 ~ 0.3%). The volatiles were a mixture of sulfide and 6 to 68% arsenic, and orange-yellow powder was scattered from the condenser wall. The dust loss is 7.4%, the unit processing capacity per day and night is 2.5~4 tons/ m2 , and the electricity consumption per ton of concentrate is 350 kWh. 99.5% of the gold, 94% of the silver is accumulated in the slag and the returned dust. According to the test results, the original data was prepared for the design of a continuous action vibration vacuum heat treatment device with a day and night processing capacity of 10 tons of concentrate. The Soviet Union's Ministry of Nonferrous Metallurgy and the Kazakh Academy of Social Sciences have taken many measures to manufacture such equipment in a factory in Kazakhstan.
Manufacture and use of industrial vacuum heat treatment equipment not only for solving arsenic removal problems and expanding gold-containing raw material bases, but also for arsenic removal and formulation of non-condensing tin -arsenic concentrates, tin-arsenic-copper concentrates, tungsten-arsenic concentrates and The comprehensive utilization process of other concentrates is necessary, because for this type of concentrate, there is still no reasonable treatment process until now. It is technically or economically important to remove arsenic from the multi-metal raw material in advance to make it non-toxic.
At present, it is ideal for manufacturing vacuum heat treatment equipment that processes several tons of bulk materials. The practical use of steam jet pumps, high-power mechanical pumps and booster pumps enables the task of rapidly manufacturing large-volume vacuum equipment to be successfully solved. It is now possible to manufacture a wide range of parts for vacuum systems in batches, as well as a variety of special steels.
Researching and adopting new processes and equipment to reduce the levels of arsenic, mercury and sulphur dioxide in exhaust gases is not only a social issue, but also of great economic importance. At present, many experts in the relevant fields are studying this issue in depth. This will greatly accelerate the resolution of the arsenic removal problem involved in all environmental protection work. It is also very important for the relevant enterprises to realize that it is necessary to study and solve this problem as soon as possible, but it does not provide direct economic benefits, but it is also of close interest to the company to improve the working conditions and the surrounding environment. Resolving these problems quickly and correctly will, to a large extent, determine the duration of the actual application and whether vacuum high temperature separation can be used to treat arsenic-containing polymetallic materials.

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