Calcination method of Jatylo Neff arsenic gold ore (1)

贾特耶洛奈Cardiff Mine Co., Ltd. is to provide arsenic trioxide to the largest companies in the chemical sector in North America -. Since 1948 it has become a larger gold producing area. However, before the toxic anti-product arsenic trioxide was sold in large quantities in the near future, it was the cause of losses to varying degrees.

The mine since 1958 to expand existing production capacity, the basic process - straight unchanged. Due to increased price of gold; makes people - the degree of re-evaluation is considered to be uneconomical to mine waste. Five years ago, the gold grade was 0.36 ounces / ton of ore, the result is a loss of 1 million US dollars, today, when the original ore grade is 0.19 ounces / ton, the situation has greatly improved. This article discusses metallurgical and environmental protection and current issues related to the roasting process for the recovery of arsenic-containing gold ore.

In Jat, the flotation concentrate is self-heating roasting in a two-fluidized combustion chamber, and the discharge of the fluid bed and cyclone dust collector is subjected to conventional cyanide recovery. The exhaust gas by - stage electrostatic precipitator hot dust, smoke is then condensed arsenic trioxide. The arsenic trioxide dust collected in the bag filter is sold directly or stored in the basement. The dust collection efficiency of the bag filter is 99.8% , and the content of arsenic trioxide is more than 90% . Today, 4,500 short tons of arsenic trioxide ( 1 short tons) are sold each year. 907.2 kg The soot collected by the electrostatic precipitator is processed by the carbon slurry method to recover the gold.

 

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The Jat Yellov Mine is located in the northwest of Yellowknife City. Four kilometers At the north of the Great Slave Lake in the northwest. The mine was put into operation in May 1948. At that time, the ore capacity was 250 tons /8 . After the process was reformed and expanded, the current processing capacity has reached 1,250 tons / day. 0.19 ounces / ton.

Jat ore is sericite schist and chlorite containing about 30% quartz, and varying amounts of calcium carbonate, iron, and from about 8 to 10% consisting of metal sulfides. Fine-grained arsenic pyrite and pyrite contain large amounts of sulfides. Also contains variable amounts of stibnite, sphalerite, pyrrhotite, brass and galena ore. Lead, iron and copper sulfonates are also present in small amounts.

It can be seen that there is very little gold. Fine-grained natural gold inclusions are found in the quartz and around the grain boundaries and in the arsenopyrite and stibnite cracks, and appear as small inclusions in the beryllium copper. However, using this as a mineral analysis value to characterize ore is far from sufficient.

Most of the gold is believed to exist in a submicroscopic state in arsenopyrite or even as a solid solution with arsenopyrite. Ore minerals are usually embedded over a relatively wide range.

Tenth apparent, this mineral is quite complex, single - the amalgamation and direct cyanidation process that will be difficult. In practice, most of the treatment methods used are mixed flotation to enrich sulfide minerals, followed by spontaneous calcination of the concentrate and calcination. The calcined sand produced by most fluidized solid roasters is suitable for cyanidation. In Jat, the purpose of the calcination is to convert the dense sulfide particles into a porous structure such that the gold particles are exposed to the cyanide infusion. The physical state of the calcination is of the utmost importance, for which the thermodynamic conditions of the calciner must be strictly controlled in order to produce a calcine having a satisfactory porosity. Control of the operation of the furnace is impeded when certain minerals are present in the feed to the furnace (e.g., sulphite and sulphonate). Although the exact behavior of these minerals is not fully understood, their presence is indeed detrimental to the extraction of gold.

From the - beginning from roasting, should the collector of arsenic contained in the roaster gas, and recovering the furnace gas mixed with such fine particles of dust in the calcine gold. Such fine dust is calcine - like electrostatic precipitator to the collector, and the gold is extracted from the activated carbon gold cyanide solution. The roasting furnace gas is cooled by the electrostatic precipitator by the introduced thin air, so that the arsenic is condensed by arsenic trioxide and then recovered in the bag filter. The exhaust gas is discharged through the chimney.

At present, the arsenic trioxide dust recovered by the bag filter is transported to the cylinder silo by wind, and then transported by truck to the US market. A few years ago, arsenic trioxide was stored in a silo in a permanent layer.

 

Roasting operation

 

The initial flotation concentrate was calcined in the Allls Chalmers Edward roaster with a total area of ​​the hearth 3,800 square feet The capacity to process concentrates is 40 tons / day.

In early 1952 , in order to expand the processing capacity of the roaster, a two-stage fluidized solid roaster was installed. This type of furnace has been modified several times (because it was not tested during installation). Which comprises - a cylindrical firing chamber, which is separated by the partition wall into two different operating chamber, the bellows being equally spaced apart, so that the amount of air supplied can be adjusted in each chamber separately. Calcine from - chamber (i.e., paragraph 1) uniform flow through the three ports in the wall turn feed into the firing chamber Sec, this firing in an oxidizing atmosphere to complete. - The dust from the section was collected by three cyclone dust collectors in series. The rear duct of the cyclone extends through the top of the roasting chamber and is embedded in a fluid bed in the second stage roasting chamber. The section firing chamber has an area of ​​about 105 square feet and the second section of the firing chamber has an area of ​​only 35 square feet. The transfer port of the duct has a large corner, and even then, the corners formed by the barrel of the roasting chamber and the partition wall are difficult to maintain fluidization. There is a dead space here, which gradually expands outwards and hinders the transfer of the material at the rear of the transfer port and the cyclone. Enlarging the transfer port means that the two-stage roasting atmosphere is out of control due to the mixing of the gases.

To progress - further improve the work of a wide processing power, installed in 1958 - large seat; two fluidized solids roaster. The furnace is also composed of two separate fluidized roasters. - the inner diameter of the fluidized bed of the section roasting furnace is 13 feet And higher than the second stage roaster 5 feet .

By flotation concentrate - Manu pump station is metered (at a concentration of 76% ore lying body), via the lance into the material - of para calciner. The level of its fluid bed is kept in the wind. Above the mouth Five feet Where. Fluidized bed overflow calcine fluoseal transfer into the valve, such a valve is - kind of U-shaped tube, has at its bottom - small fluidized injector, but also on the discharge side - of the small secondary air injection In order to lift the calcine to the feed tube of the two-stage roaster. The wind pressure in the two injectors is 20 pounds / square inch, at this time air flow 14~ 20 cubic feet / points.

Pass - stage 3,700 cubic feet / Min Spencer turbine compressor at a gauge 4 pounds / square inch air into the first - the bellows section through the firing chamber and then air \ into the fluidized bed, 10 inches Tuyere 193 tuyeres, each - 3/16 tuyere six air holes. From the dusty gas - enters the second section of the free board section.

- of paragraph roaster calcine from entering the second stage fluidized bed calciner. The inner diameter of the second stage roaster is 9.5 feet , 10 inches There are 100 plum blossoms on the center .

Pass two 2100 cubic feet / Min Spencer turbine compressor feed air gauge at 4 pounds / square inch. Fluid bed overflow tube is higher than tuyere 5 feet And the fluidized bed overflow calcine directly into - a quenching tank. All quenched roasting products are pumped to the calcine washing system and sent to cyanidation.

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