CN1156762A - Process for directly producing cadmium sulfate from zinc cadmium slag - Google Patents
Process for directly producing cadmium sulfate from zinc cadmium slag Download PDFInfo
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- CN1156762A CN1156762A CN96100899A CN96100899A CN1156762A CN 1156762 A CN1156762 A CN 1156762A CN 96100899 A CN96100899 A CN 96100899A CN 96100899 A CN96100899 A CN 96100899A CN 1156762 A CN1156762 A CN 1156762A
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Abstract
A process for direct production of cadmium sulfate with Zn-Cd slags includes such steps as mixing Zn-Cd slags with zinc sulfate, drying, crushing, mixing with chemical assistant, calcine to change Zn in slags into zinc oxide and Cd into cadmium sulfate, aqueous extraction of cadmium sulfate solution, regulating pH value of cadmium sulfate solution to about 4 for direct use, or crystallization to obtain solid cadmium sulfate, and preparing zinc salt from zinc oxide slags or smelting zinc.
Description
The invention relates to a method for directly producing cadmium sulfate from zinc-cadmium slag, in particular to a method for directly producing cadmium sulfate from zinc-cadmium slag by adding a chemical additive, reacting the slag in a dry method, and then leaching cadmium sulfate with water.
The zinc-cadmium slag is mixture slag mainly containing zinc and cadmium, and mainly comes from ① zinc sulfate and lithopone production zinc-cadmium replacement slag, ② zinc-lead and other non-ferrous metal pyrometallurgical zinc-cadmium-containing smoke slag, ③ other zinc-cadmium-containing waste slag, and the zinc-cadmium slag does not contain a large amount of zinc chloride or zinc nitrate and other zinc compounds influencing the implementation of the invention and the purity of cadmium sulfate.
For the treatment of zinc cadmium slag, people have a very mature process for a long time. Namely zinc cadmium slagDissolving with sulfuric acid, regulating pH value to a certain acidity, adding zinc powder at proper temperature to replace cadmium in the solution to make it become sponge and precipitate cadmium, and according to the purity of obtained sponge cadmium, determining whether to make acid dissolution again-zinc powder replacement or direct refining3As) gas is generated, the production safety requirement is strict, ② expensive zinc powder is used for replacing cadmium, the production cost is higher, ③ when the cadmium content in slag is lower or the operation condition is not well controlled, the purity of the sponge cadmium is not high, further refining is needed to remove zinc impurities, if ④ wants to prepare cadmium sulfate, the sponge cadmium needs to be dissolved by sulfuric acid again, so that the process is more complex, and the cost is higher.
With the development of solvent extraction technology, people naturally think of treating and recovering cadmium and zinc in cadmium-zinc slag by using solvent extraction technology, a typical example is to use an acidic phosphine extraction agent to extract zinc in a cadmium sulfate solution so as to separate the zinc from the cadmium, but the method is only suitable for the condition that a large amount ofcadmium sulfate solution contains a small amount of zinc sulfate, if the zinc content in the solution is higher, the concentration of the extraction agent and the extraction stages are increased, the loss of the extraction agent and the equipment investment are correspondingly increased, and the method is not generally applied all the time. Other extraction methods also use TBP to extract CdI4 -However, this method is mainly used for removing cadmium impurity from zinc, and is suitable for waste residue with low cadmium content (1-2%), and the iodide is expensive, so that the method has not been greatly developed. According to the research on extracting zinc by TBP in Warren spring laboratory, the separation effect of zinc and cadmium is good, but a large amount of chloride ions are added into the solution, so that the TBP can extract zinc and cadmium is left in the solution.
French patent 002399480 proposes a new zinc-cadmium replacement slag in electrolytic zinc production processAnd (4) a treatment method. The main process comprises the following steps: adding neutral zinc sulfate solution into zinc-cadmium slag in a reaction kettleAt a certain temperature, the following reactions are carried out ① the process for treating the zinc-cadmium slag is carried out under the condition that the content of zinc sulfate in the slag is not enough to convert all cadmium in the slag into cadmium sulfate, which requires to artificially add zinc sulfate into a reaction kettle according to the stoichiometric amount, if the zinc sulfate is added too much, the leached cadmium sulfate solution contains partial zinc sulfate, which affects the purity of the cadmium sulfate, and if the zinc sulfate is added too little, the leaching of partial cadmium is affected, which reduces the recovery rate of cadmium.
The invention aims to provide a method for directly producing cadmium sulfate from zinc-cadmium slag, which has the advantages of simple process, low cost, easy operation, high zinc-cadmium recovery rate and high product purity, and simultaneously has wider application objects.
The method for directly producing cadmium sulfate from zinc-cadmium slag comprises the following steps: (see the figure)
Determining whether to supplement zinc sulfate into the zinc-cadmium slag according to the content of the zinc sulfate in the zinc-cadmium slag to be treated; the supplement method comprises the following steps:
① when the mole number of zinc sulfate in the zinc-cadmium slag to be treated is less than that of cadmium, zinc sulfate is added to the zinc-cadmium slag, the mole number of zinc sulfate in the zinc-cadmium slag after zinc sulfate addition is equal to or more than that of cadmium in the slag, and the added zinc sulfate is fully mixed with the slag.
② when the mol number of zinc sulfate contained in the zinc-cadmium slag to be treated is larger than or equal to the mol number of cadmium in the slag, zinc sulfate is not supplemented in the zinc-cadmium slag, and the treatment is directly carried out according to the step (II).
And (II) drying and crushing the zinc-cadmium slag obtained in the step (I) to ensure that the granularity of a slag sample is less than 50 meshes, preferably less than 150 meshes.
And (III) mixing a chemical roasting aid into the zinc-cadmium slag crushed in the step (II), wherein the weight of the mixed aid is 0-20% of that of the crushed slag, and the concrete steps are as follows:
① if the mole number of zinc sulfate in the crushed zinc-cadmium slag is exactly equal to that of cadmium in the slag, the slag can be directly processed accordingto the step (IV) without mixing chemical additives (namely, the weight of the chemical additives is 0 percent of the weight of dry slag).
② when the mole number of zinc sulfate in the crushed zinc-cadmium slag is larger than that of cadmium, chemical auxiliary agents are mixed in the crushed zinc-cadmium slag, the name of the auxiliary agent is calcium oxide, calcium hydroxide, calcium carbonate, barium oxide and strontium carbonate, the mixed auxiliary agent can be one or a mixture of more than two of the above agents, the dosage is 0-20% of the weight of the crushed slag, preferably, activated calcium oxide is selected, the optimal dosage is 3-5% of the weight of the slag, and the granularity of the mixed auxiliary agent is preferably less than 200 meshes.
(IV) roasting: and (3) roasting the slag sample in the step (III) under the condition of introducing air, wherein the roasting condition is as follows:
① when the mole number of zinc sulfate in the zinc-cadmium slag after crushing is equal to the mole number of cadmium in the slag (i.e. no chemical additive is mixed in the slag), the roasting temperature can be 400-760 ℃, preferably 600-750 ℃, the roasting time should be more than 1.5 hours, preferably more than 2 hours, and the reaction is as follows:
② when the mole number of zinc sulfate in the crushed slag is larger than that of cadmium in the slag (i.e. the slag is mixed with chemical assistant), the roasting temperature is 600-760 ℃, preferably 680-750 ℃, the roasting time is more than 1.5 hours, preferably more than 2 hours, taking calcium oxide as the assistant, the reaction is as follows:
(V) leaching the roasted product with water to separate cadmium sulfate
And (4) leaching the roasted product obtained in the step (IV) by using neutral water to dissolve cadmium sulfate in water, and leaving zinc in the precipitation slag in the form of zinc oxide. The reaction is as follows:
then separating the aqueous solution from the precipitate slag by filtration.
Sixthly, preparing cadmium sulfate: regulating the pH value of the cadmium sulfate solution obtained in the step (five) to be about 4 by using sulfuric acid to obtain cadmium sulfate liquid, and if the cadmium sulfate needs to be crystallized, preparing the crystallized cadmium sulfate by using a common method.
Examples and effects
The first embodiment is as follows: taking 20kg of zinc-cadmium replacement slag (the slag contains 15 percent of zinc, 12 percent of cadmium and 25 percent of zinc sulfate) generated in the process of producing lithopone, and calculating that the mole number of the zinc sulfate in the slag is more than that of the cadmium, so according to the method, starting from the step (two), adding 4 percent of 200 meshes of active calcium oxide, and roasting for 2 hours at 720 ℃. 60 liters of cadmium sulfate-containing aqueous solution with cadmium content of 2340g is finally obtained. Heating and evaporating the aqueous solution to crystallize 3CdSO4·8H2And O, all indexes of the product meet the requirements of industrial cadmium sulfate through analysis.
Example two: 1000g of zinc pyrometallurgical smoke slag (containing 20% of zinc and 23% of cadmium) is taken, and the slag does not contain zinc sulfate, so according to the method, from the step (one), zinc sulfate with the same mole number as cadmium is added, chemical additives are not added, namely the addition amount of the additives is 0, and the mixture is roasted at 500 ℃ for 2 hours, and finally, 3000ml of cadmium-containing solution is obtained, wherein the cadmium content is 227g, and the zinc content is 0.98 g.
Example three: adding Na into the zinc-cadmium wastewater2CO3500g of treated precipitation slag (the slag contains 25.6% of zinc and 6.5% of cadmium, and the slag contains ZnSO43.7 percent) and adding 60g of zinc sulfate into the slag to ensure that the mole number of the zinc sulfate in the slag is more than that of the cadmium. According to the method, the auxiliary agent BaO60g is added from the step (one), and the mixture is roasted for 1.5 hours at the temperature of 740 ℃, and finally, 1500ml of cadmium-containing solution, 58.97g of cadmium sulfate and 0.6g of zinc are obtained.
Example four: taking 5kg of zinc-cadmium replacement slag (the slag contains 20 percent of zinc, 9.8 percent of cadmium and 16.3 percent of zinc sulfate) in the production process of zinc sulfate, and directly starting from the step (IV) according to the method to finally obtain 14 liters of cadmium sulfate solution with higher zinc sulfate content, wherein the cadmium sulfate content is 883.06g, and the zinc sulfate content is 83 g.
Example five: taking 100g of zinc-containing cadmium waste residue (containing 7.6% of zinc and 5.1% of cadmium) in the production process of the plastic stabilizer, wherein the residue contains a large amount of organic matters and does not contain zinc sulfate, firstly ashing at low temperature to remove the organic matters, and then beginning from the step (one) according to the method to finally obtain 250ml of solution, wherein the solution contains 9.2g of cadmium sulfate.
The method has the advantages of simple process, easy operation, low cost and wide application range, and can directly produce industrial-grade cadmium sulfate from the zinc-cadmium slag and simultaneously realize the separation and recovery of the zinc and the cadmium in the waste slag. Similar to the conventional methods, has better economic benefit.
Claims (12)
1. A process for directly preparing cadmium sulfate from zinc-cadmium dregs includes such steps as adding zinc sulfate to zinc-cadmium dregs to make its mole number equal to or greater than that of cadmium, mixing, drying and pulverizing the dregs ②, mixing chemical assistants ③ with dregs ④, calcining dregs to convert zinc to zinc oxide and cadmium to cadmium sulfate, immersing ⑤ in water to dissolve cadmium sulfate in water while the water-insoluble dregs is crude zinc oxide, separating solution from immersed dregs, regulating pH value of aqueous solution of cadmium sulfate prepared in step ⑤ to 4, and evaporating for crystallizing to obtain solid cadmium sulfate or directly using it as liquid cadmium sulfate product.
2. The method as claimed in claim 1, which begins with step ① when the zinc cadmium slag itself contains zinc sulfate in a molar amount less than that of cadmium.
3. The method as claimed in claim 1, wherein when the zinc-cadmium slag itself contains zinc sulfate in a mole number equal to that of cadmium in the slag, the method for directly producing cadmium sulfate from the zinc-cadmium slag begins at step ②.
4. The method as claimed in claim 1, wherein when the zinc-cadmium slag itself contains zinc sulfate in a molar amount greater than that of cadmium in the slag, the method for directly producing cadmium sulfate from the zinc-cadmium slag begins at step ②.
5. The method of claim 1 or 4 for directly producing cadmium sulfate from zinc cadmium slag, wherein when the zinc cadmium slag itself contains zinc sulfate in a molar amount greater than that of cadmium in the slag and the implementer has no strict requirement on the zinc impurity content in the cadmium sulfate solution obtained after water immersion or needs to prepare a cadmium sulfate solution containing a small amount of zinc sulfate, the method for directly producing cadmium sulfate from zinc cadmium slag begins at step ④.
6. The method of claims 1, 2, 3 and 4, wherein: the crushing grain size of the dried zinc cadmium slag is less than 50 meshes, and preferably less than 150 meshes.
7. The method according to claims 1, 2, 3 and 4, wherein the chemical auxiliary agents are: the granularity of the material is less than 200 meshes, and the material is one or a mixture of more than two of calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, barium carbonate, strontium oxide, strontium hydroxide and strontium carbonate.
8. A method as in claim 7 wherein the chemical adjuvant used is preferably single activated calcium oxide of less than 200 mesh size.
9. A method as in claim 7 wherein the amount of chemical adjuvant is 0-20% by weight of the dried zinc cadmium slag, preferably 3-5% by weight of the dried slag of activated calcium oxide.
10. A method as claimed in claims 1, 2, 3 and 4 wherein the calcination temperature is between 400 ℃ and 760 ℃ if the number of moles of zinc sulfate in the crushed zinc-cadmium slag is equal to the number of moles of cadmium in the slag.
11. A method according to claims 1, 2, 3 and 4, characterized in that if the number of moles of zinc sulphate in the crushed zinc-cadmium slag is greater than the number of moles of cadmium in the slag, the roasting temperature is between 600 ℃ and 760 ℃, preferably between 650 ℃ and 760 ℃; the calcination time should be greater than 1.5 hours, preferably greater than 2 hours.
12. A process as claimed in claim 5, wherein the calcination temperature is between 400 ℃ and 760 ℃. The calcination time should be greater than 1.5 hours, preferably greater than 2 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96100899A CN1156762A (en) | 1996-02-06 | 1996-02-06 | Process for directly producing cadmium sulfate from zinc cadmium slag |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96100899A CN1156762A (en) | 1996-02-06 | 1996-02-06 | Process for directly producing cadmium sulfate from zinc cadmium slag |
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| CN1156762A true CN1156762A (en) | 1997-08-13 |
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| CN96100899A Pending CN1156762A (en) | 1996-02-06 | 1996-02-06 | Process for directly producing cadmium sulfate from zinc cadmium slag |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103028587A (en) * | 2011-09-30 | 2013-04-10 | 深圳市明灯科技有限公司 | Method for solidifying arsenic-calcium residue or arsenic-iron residue |
| RU2479488C2 (en) * | 2011-02-22 | 2013-04-20 | Софья Павловна Бухман | Method of producing solutions with different concentration of cadmium sulphate |
| CN103103357A (en) * | 2012-11-23 | 2013-05-15 | 陈泉兴 | Method for drying, calcining and cooling metal slag material |
| CN103556180A (en) * | 2013-10-31 | 2014-02-05 | 中南大学 | Method for recovering copper and cadmium from copper and cadmium slag and device for recovering cadmium from zinc sulfate solution rich in cadmium |
| CN108097715A (en) * | 2017-12-29 | 2018-06-01 | 成都新柯力化工科技有限公司 | A kind of method using the leaching and repairing cadmium polluted soil of symbiosis |
-
1996
- 1996-02-06 CN CN96100899A patent/CN1156762A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2479488C2 (en) * | 2011-02-22 | 2013-04-20 | Софья Павловна Бухман | Method of producing solutions with different concentration of cadmium sulphate |
| CN103028587A (en) * | 2011-09-30 | 2013-04-10 | 深圳市明灯科技有限公司 | Method for solidifying arsenic-calcium residue or arsenic-iron residue |
| CN103103357A (en) * | 2012-11-23 | 2013-05-15 | 陈泉兴 | Method for drying, calcining and cooling metal slag material |
| CN103103357B (en) * | 2012-11-23 | 2014-04-09 | 陈泉兴 | Method for drying, calcining and cooling metal slag material |
| CN103556180A (en) * | 2013-10-31 | 2014-02-05 | 中南大学 | Method for recovering copper and cadmium from copper and cadmium slag and device for recovering cadmium from zinc sulfate solution rich in cadmium |
| CN108097715A (en) * | 2017-12-29 | 2018-06-01 | 成都新柯力化工科技有限公司 | A kind of method using the leaching and repairing cadmium polluted soil of symbiosis |
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