Recovery of thorium resources in lead anode mud

I. Resources and utilization status of Zhuye

(A) antimony resources

1994 Copper, Lead Zinc Yield Zhuye three products to 225,000 t, the amount of antimony is brought into the plant material is estimated 431t, the distribution of antimony in the starting material and product are respectively shown in Table 1 and Table 2.

Table 1 The amount of sputum brought in from the raw materials

Table 2 Distribution of 锑 in the products of the smelting system %

The lead in the lead system has a more concentrated go-lead electrolytic anode slime. However, after entering the gold and silver smelting, it is relatively dispersed. The concentrated ones are smelting soot, refining soot and slag, and the latter two return to the lead system to carry out a cycle. About half of the ruthenium in the zinc system is stored in the volatile kiln residue, and 1/4 enters the zinc oxide leaching slag and is transferred to the lead system. The copper smelting smelting is mainly from the lead system copper of the lead system. After copper smelting, 75% of the bismuth in the blister copper enters the reflective slag, 18% enters the anode mud, and the anode mud is transferred to the gold and silver smelting.

(2) Utilization status

1. Recovery of crude ruthenium from white arsenic residue

The use of soot to produce white arsenic, the residue of which is sent to the lead system to recover the crude lead process, the process flow is shown in Figure 1.

Figure 1 Flow chart for recovery of crude ruthenium from white arsenic residue

2. Production of As-Sb alloy

The process flow is: mixing soot with charcoal powder, distilling and condensing to obtain As-Sb alloy.

3. Recovery of hydrazine from high pressure water leaching residue

The process flow is shown in Figure 2.

Figure 2 Flow chart of recovery of hydrazine from water slag

For various reasons, the above processes failed to achieve industrial production.

4, the production of glass clarifying agent

Using As-Sb ash as raw material, it cooperates with many glass factories and special auxiliaries factories to produce glass clarifying agent, which solves the problem of long-term accumulation of ash, but its price is very cheap, which is not worthwhile in the long run.

2. Recycling of cesium resources in several domestic smelting plants

(1) A lead factory in Northeast China

A lead plant in the Northeast has been recycling resources from the 1970s and is at the forefront of various manufacturers. At the beginning, the raw materials of the tantalum were processed into metal tantalum ingots. From 1985 onwards, only tantalum trioxide was produced. The annual output was 60-100 tons, and the comprehensive recovery rate of rhodium was 50%-65.5%. The current selling price is 31,000 yuan ∕t (including tax price), and the production cost can be controlled at around 11,000 yuan/t.

1, raw materials

The raw materials are the soot (primary soot) obtained by collecting dust from the gold and silver smelting flue gas through Venturi and the soot (secondary soot) obtained by collecting the dust from the ventilating flue gas in Venturi. The composition is shown in Table 3.

Table 3 Soot composition %

2, the process

Both the soda with soot, powder coal smelting reduction to obtain an antimony-containing antimony alloy is greater than 55%, the alloy is melted in the pot volatilization, bubbling air, resulting antimony trioxide and lead-bismuth alloy. The antimony trioxide is refined and refined by reductive smelting and refining. The process flow is shown in Figure 3, and the product composition requirements are shown in Table 4.

Table 4 Quality requirements for each stage of the product %

Figure 3 锑 production process flow chart

(2) A factory in Northwest China

Since 1983, a plant in the northwest has started the wet extraction of bismuth and antimony from lead anode mud. The process of extracting gold and silver by leaching slag from sodium sulphide and leaching slag from slag slag is carried out.

1, raw materials

Anode mixed component (%): Sb43-46, Bi6-8, Pb7-9, Cu0.8-3, Fe0.2-0.8, As<0.2, Au0.1-0.15, Ag15 left-right.

2, the process

The process flow is shown in Figure 4.

Figure 4 Lead anode mixing process flow chart

3, process conditions

Low acid, normal temperature pretreatment, drying and oxidation at 300 °C. Leaching 锑: Sodium sulfide solution leaching, time 1 ~ 2h, temperature > 98 ° C, hot filtered, hot water wash. Electrowinning enthalpy: temperature 32 ~ 40 ° C, tank pressure 2.2 ~ 2.8V, after electrolysis liquid containing Sb> 16 g / l, anode current density of 250 ~ 310A / m ² . Leaching enthalpy; temperature > 95 ° C, liquid-solid ratio 8:1, time 2 h, starting H ₂ SO ₄ 100-120 g / l, NaCl 150 g / l. Bismuth substitution: replacing the scrap iron at room temperature, the resulting sponge containing bismuth Bi50% ~ 77%. The sponge is dried and smelted into a coarse mash, and the treated anode is smelted into a noble lead.

4. Main technical and economic indicators

The leaching rate is 92%-96%, the 锑 current efficiency is >75%, the 铋 leaching rate is >90%, the 铋 replacement rate is >96%, the cathode 锑 grade is >97%, the crude 铋 grade is >94%, and the gold and silver smelting recovery rate> 99%.

(3) Hunan Lead Factory

A smelting lead plant in Hunan began to treat copper and lead anode mud together in 1987. In the second half of 1990, the wet process anode slime technology was promoted and applied, and the lead anode mud-fire method was used to prepare the gold and silver production process.

1, raw materials

Lead anode mud component (%): Au 0.04 to 0.05, Ag 10 to 15, Cu 5 to 8, Pb 7 to 12, Bi 20 to 27, As 4 to 10, Sb 25 to 27, and H ₂ O 25 to 35.

2, the process

The process flow is shown in Figure 5.

Figure 5 Flow chart of lead anode mud chloride pretreatment

3. Main technical conditions

Chloride salt leaching: The concentration of hydrochloric acid at the end of the leaching is 2 to 2.5 mol/l, the ratio of solid to liquid is 1:4, and the temperature is 80 °C. Recovery of barium, strontium, copper: leaching solution components (g / l); Bi35 ~ 40, Sb 40 ~ 50, Cu8 ~ 10, Pb1 ~ 3. Hydrolyzed sedimentation: temperature 50 ~ 60 ° C, 3 to 3.5 times diluted. Neutralization and sinking. The endpoint pH is 2.5 to 3.0, room temperature. Replacement of copper: pH 2 ~ 2.5, temperature 70 ° C. Wastewater treatment: use lime milk word pH to 11 ~ 12, add ferric chloride, blast, clarify and then efflux.

4. Main technical indicators

Recovery rate of each valuable metal (%): Au>99, Ag>98, Sb80-85, Bi90-95, Cu60-70. Consumption per tonne of anode mud material (t): hydrochloric acid 2 to 2.2, soda ash 0.8, iron powder 0.08, ferric chloride 0.023, lime 0.4.

(4) A lead factory in Henan

The factory originally used the fire method to treat lead anode mud, and the recovery rate of gold and silver was low, 90% and 80% respectively. In the 1980s, Zhongnan University of Technology helped to develop a full wet process, which achieved a good recovery rate of gold and silver, and recovered valuable metals such as bismuth, antimony and copper.

1, raw materials

Lead and anode mixed components (%); Au 0.8, Ag 8, Sb 40, Pb10, Bi 6, Cu 3, Ag1.

2, the process

The process flow is shown in Figure 6.

Figure 6 Pipeline anode mud wet process flow chart

3. Process conditions and indicators (see Table 5)

Table 5 Process conditions and indicators

Third, discussion

The comparison of the above four enterprise processes is shown in Table 6.

Table 6 Comparison of 锑 recycling process

(1) Impact on gold and silver smelting

The raw material used in the recovery of cesium in a factory is the venturi dust of gold and silver smelting, so it has no effect on gold and silver smelting. This is a great advantage. The other methods must pre-process the anode mixture, which has little theoretical impact. But mechanical losses are inevitable. The recovery rate of gold and silver smelting in our factory is 99.01% (1994 data). If we want to recycle 锑, we need to do not affect the principle of gold and silver smelting.

(3) Preventing the adverse effects of arsenic

The adverse effects of arsenic are mainly caused by pollution and difficult to separate from cockroaches. In the smelters in Northeast China and Henan, the raw materials contain not much arsenic, and the negative effect of arsenic in the recovery process of strontium is not significant. The lead anode muds of the other two plants contain higher arsenic, and the distribution of arsenic in the smelting process is scattered, which may adversely affect the environment and the smelting process.

(3) Economic rationality

In order to make the economic recovery of cockroaches reasonable, it is necessary to have little impact on the recovery rate of gold and silver, to avoid damage to this part of the benefits, and at the same time to achieve better economic returns and higher output than enthalpy. The method of a Hunan plant in the anode mud pretreatment stage has little effect on the recovery rate of gold and silver. The comprehensive recovery of strontium, barium and copper also has certain economic benefits.

Fourth, the proposal of the use of resources

The composition of lead and anode in Zhuye in 1994 is shown in Table 7. The total amount of anode mud is 516t, and a part of the intermediate product is removed from the lead smelting system. The available resources are estimated to be 380~400t. .

Table 7 Lead anode mud composition %

The content and distribution of arsenic and antimony in the intermediate materials produced by gold and silver smelting are shown in Table 8. If thorium is recovered from smelting soot, the available plutonium resources are estimated at 296 tons.

Table 8 Contents and distribution of arsenic and antimony in intermediate materials

Whether it is recovering strontium from lead anode mud or recovering strontium from gold and silver smelting soot, for our factory, there is a problem that the raw material contains too much arsenic, and arsenic must be removed before recycling. At present, there is no ready-made process to copy, it is recommended to select the test as follows.

(1) Removal of arsenic

According to the difference in saturated vapor pressure between arsenic trioxide and antimony trioxide, arsenic is partially separated by calcination, and this method has been adopted in factories. However, its equipment investment is relatively large, and it requires a relatively large dust collection facility. The air pollution in the workplace is difficult to control. In addition, there may be problems with the bonding of the charge to the materials of our factory.

Separation of arsenic based on the difference in water solubility between arsenic trioxide and antimony trioxide has also been effectively employed in factories. In the dust collection process, Shenqiu uses venturi to collect dust, so that most of the arsenic enters the water phase, and then the arsenic calcium slag is obtained from the water phase. The arsenic calcium slag is used by the glass factory to clarify the glass, while the venturi smoke contains Arsenic is reduced to 2% to 5% for recovery. Guangxi trioxide factory using a solubility in water increases rapidly with temperature properties of the tin-containing dust of high arsenic (%): As24.31, Sb 2.13 , Sn 25.17, Pb 4.25, Zn 1.17, Fe8.67 wet processing, often using The process of preparing white arsenic by the process of purifying hot water leaching, purifying and concentrating crystals has also been successful. The process of arsenic removal by water immersion is relatively simple, the equipment is not complicated, the pollution can be controlled, and it is easy to launch. It is recommended to be preferred.

In addition, our factory is now in contact with a foreign company using arsenic trioxide and antimony trioxide, and the method of separating arsenic in electric dust collection is also considered.

(2) Recovery of cockroaches

The key to recovering plutonium from lead anode mud or recovering plutonium from gold and silver smelting soot is the comparison of economic benefits, that is, the effect of plutonium recovery process on silver grazing rate. According to the amount of silver in the lead anode mud of our factory, if the recovery rate is reduced by 0.5%, the loss of silver is 0.642t, which is 867,000 yuan. According to the data of Shenye, the cost of recycling 1t bismuth (yttria) is 11,000 yuan, the price is 26,500 yuan (excluding tax), and the gross profit is about 15,000 yuan, so it is necessary to recover 58t 锑 to compensate for the above losses of silver. It should be taken seriously. The economic benefits of the two helium recovery schemes are shown in Table 9.

Table 9 Comparison of economic efficiency of two helium recovery schemes

Our factory has conducted a preliminary test on lead anode mud pretreatment. The results will not affect the silver recovery rate too much, and the strontium, barium and copper in the anode mud can be recovered, and the comprehensive recovery rate of strontium is estimated. It is better than the current process, which is also beneficial to improve the gold and silver smelting and related technical and economic indicators under the existing process conditions.

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