First, the process.
As shown in Figure 1. Including leaching, purification, crystallization, conversion, drying and other processes.
Figure 1 Process for the production of yellow dans by lead chloride slag
Second, the main technical conditions.
Leaching: After the ball slag is ball milled, it is leached with saturated brine, the liquid-solid ratio is 10:1, the leaching temperature is 109 ° C, the leaching solution pH is 3-5, and the leaching solution contains lead higher than 65 g/l.
Purification of copper : Adding Na 2 S or sponge lead to remove copper, the liquid temperature is 90 ° C, and the copper content after copper removal is less than 0.001 g / liter.
Purification and iron removal: adding hydrogen peroxide or sodium hypochlorite to remove iron (sodium hypochlorite is prepared by using chlorine gas into 30% liquid alkali), and the iron content after de-ironing is less than 0.0001 g/l.
Cooling crystallization: using jacketed circulating cold water cooling, mechanical stirring, the solubility of lead chloride in sodium chloride solution decreases with temperature, and PbCl 2 crystals are precipitated. The mother liquor is returned to the leaching.
Conversion: PbCl 2 crystals were washed with distilled water and added to a 30% liquid base. The response is:
PbCl 2 +2NaOH = PbO + 2NaCl + H 2 O
The industrial liquid alkali used first removes iron with MgCl 2 , generally 1 to 5 kg per ton of liquid alkali plus MgCl 2 , after the iron is heated, the liquid alkali is heated to 95 ° C for conversion, and the liquid containing NaOH is not less than 2.5 N after the conversion, so as to avoid Other basic lead salts are formed.
Washing and drying: The alkali-containing PbO is filtered by a centrifuge, and the mother liquor is concentrated to a 30% liquid alkali after filtration, and returned for conversion. The PbO crystals are washed with hot distilled water to a pH of 8, and indirectly heated to 105 ° C with steam, and dried and sieved to form a finished yellow dan.
Third, the main equipment.
One ball mill : leaching tank, copper removal tank, iron removal tank, cooling tank, conversion tank, one jacketed enamel reaction kettle; one centrifugal filter; one rotary drum dryer; Several pumps.
Fourth, product use.
Huang Dan used as a drier in paint: ceramic industry as glaze; used in the production of lead glass with optical glass, optical fiber, electronic vacuum glass, etc.; can also produce lead nitrate, lead acetate, lead chrome yellow; industry.
V. Output quality (%).
A PbO-containing product is not less than 99, the metal lead is not higher than 0.1, PbO 2 not more than 0.2, nitrate insolubles not higher than 0.2, sieve residue (- 200 days) not more than 0.2; product contains two PbO is not lower than 97, Pb is not higher than 0.3, PbO 2 is not higher than 0.5, nitric acid insoluble matter is not higher than 0.5, and sieve residue (-200 mesh) is not higher than 0.5.
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