Boiling roasting method for processing gold arsenic ore abroad (6)

The balance sheet metal, gold recovery process is obtained from the calcined material for 97%.

The device was later modified. The calciner was changed to a single chamber furnace in place of the boiling roasting method instead of the calcination in a mechanical roaster. The equipment for industrial testing is shown in Figure 5 .

The basic task of roasting is to remove arsenic from the concentrate and to obtain arsenic trioxide for industrial use. Obtaining arsenic dioxide is very difficult. This is because there are no similar examples of industrial production at home and abroad.

The modified calciner has a rectangular cross section. Its bottom area is 3.4 meters ² , high 1 meter . The height from the bottom of the furnace to the top of the furnace 6 meters . Lined with clay brick in the roaster. The bottom of the furnace is made of heat-resistant concrete and has a dome-shaped nozzle. The effective section of the nozzle is 0.8% of the area of â€‹â€‹the bottom of the furnace .

The exhaust gas discharged from the furnace is purified in a UH-15 type dust remover and a BYI-2.4 type electric dust collector which are sequentially arranged . The dust collector, flue and electric precipitator can be insulated to prevent condensation of arsenic trioxide vapor. In order to condense and collect the arsenic trioxide vapor, a crystallization chamber is installed after the electric precipitator. The purified gas passes through the crystallization chamber and leaves the workshop. 800 meters The far chimney is discharged into the atmosphere.

The concentrate after drying (to reach 4~5% moisture) is sent to the baking furnace for baking Â burn. This type of baking furnace is different from similar devices in foreign countries. Its main feature is the roasting of the pulp. The roasting of the concentrate slurry with this device is eliminated due to the need to obtain arsenic trioxide.

This device has been tested with two concentrate roasting systems: complete oxidation of sulfides and volatilization of arsenic into the gas phase.

When the amount of oxygen is insufficient to completely oxidize the sulfide, the arsenic has the highest volatilization rate.

When the air consumption is equal to 130~135% of the theoretical consumption , the temperature is 750~ 850 Â°C When the system is completely oxidized, the system can be guaranteed. When sulphide complete oxidation (system A ) and arsenic preferential volatility (system B ) are carried out, the process parameters of boiling roasting are as follows:

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Institution A Â Â Â Â Â Â Â Institution B

Air consumption is the theoretical consumption of % Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 130~135 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 80~90

Roaster unit processing capacity, tons / m ² Â· day and night Â Â Â Â 3.5~4.5 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 6.5~7.5

Boiling layer temperature, Â°C Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 750~850 Â Â Â Â Â Â 550~580

The content of the calcined from the furnace, %

S total Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0.4~0.6 Â Â Â Â Â Â Â 12~20

Ss Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0.1~0.2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 7.2~15.0

As Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1~1.5 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0.35~0.65

Arsenic recovery rate transferred to the gas phase, % Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 65~75 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 80~85

In order to use the roaster frequently, a system of preferential arsenic arsenic should be used.

In the case of insufficient oxygen and calcination temperature of 500~ 850 Â°C (The optimal temperature selected is 550~ 550 Â°C Under the conditions of the test, the working system of the roaster was examined. It is proved that this - roasting system can guarantee the temperature conditions necessary for the electrostatic precipitator and the entire gas pipe. Under the above-mentioned calcination temperature and air consumption ( 80-90% of its theoretical consumption ), the oxygen content in the gas in the lower part of the furnace top fluctuates between 0 and 1.5% , and the content of SO ₂ is 10 to 12% .

The amount of dust blown out in the roaster is 20% of the concentrate . Under the conditions of long-term operation of the electrostatic precipitator , qualified industrial arsenic anhydride containing 92~99% As ₂ O ₃ can be obtained . The gold grade in arsenic anhydride is 1~ 2 grams / ton. If the dust in the gas before the electrostatic precipitator does not exceed 5~ 8 grams / M ^2, which is best. The actual recovery of gold in the calcine is 96.1~97% . However, if the effective utilization factor of the electrostatic precipitator is increased and the mechanical loss is eliminated, the recovery rate of gold can be improved.

Gold enrichment in the calcine often occurs in the hearth during the roasting process, particularly at the bottom of the furnace. This has happened in factories abroad. After long-term work in the roaster, the grade of gold in the calcine of the bottom of the furnace can exceed 2~3 kg / ton or even higher. The reason for this is that free gold in the concentrate and gold that is dissociated during the oxidation of the sulfide precipitate in the gas stream.

"Dala Song" Bureau of Mines test apparatus is used to Bureau of refractory gold ore concentrates arsenic pyrite roasting station device 1 is. It was officially put into industrial production in 1967 . Â Â Â

The Irkutsk branch of the National Institute of Rare Metals and the National Science Institute of Non-ferrous Metals have studied the oxidative roasting of the Mugong gold-bearing concentrate in boiling roasting under laboratory conditions. In 1966 , the All-Sugar Nonferrous Metals Research Institute conducted a semi-industrial test on the two-stage roasting of argillaceous gold-bearing concentrates from a deposit in Kazakhstan. This concentrate is characterized by the absence of free gold. All gold in the concentrate is symbiotic with arsenic pyrite.

The equipment connection diagram of the semi-industrial device is shown in Figure 6 .

Figure 6 Contact diagram of industrial equipment for muddy gold-bearing concentrate

When the firing temperature is low Paragraph 1 (500 ~ 559 Â°C And in a weak oxygen atmosphere, arsenic is greatly volatilized. During firing Paragraph II, after the excess air and increasing the firing temperature, sulfur and carbon it will be completely oxidized.

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