Methods for converting copper nitrate to copper sulfate

Abstract

This invention discloses a method for converting copper nitrate to copper sulfate, comprising a copper nitrate concentration step, a copper nitrate crystallization step, a sulfuric acid replacement step, and a copper sulfate crystallization step. The main steps involve mixing a copper nitrate solution with copper material (derived from a copper-containing alloy) to dissolve the copper and consume free acid. The resulting reaction solution is heated, evaporated, concentrated, and then cooled to crystallize and obtain copper nitrate crystals. The copper nitrate crystals are then directly replaced with sulfuric acid at a low temperature of 25°C to 35°C to generate copper sulfate. The reaction is terminated by consuming residual acid with copper powder. Subsequently, solid-liquid separation is performed to obtain copper sulfate crystals. The entire process requires no addition of alkali, the intermediate byproduct nitric acid can be recycled and reused, and the nitrate nitrogen removal rate can reach 99.56%, effectively reducing reagent costs and wastewater treatment burden, thus demonstrating circular economy benefits.

Claims

1. A method for converting copper nitrate to copper sulfate, comprising the following steps: a copper nitrate concentration step (S30), wherein a copper material (S21) and a copper nitrate solution (33) are mixed, and the copper material (S21) is dissolved in the copper nitrate solution (33) to consume free acid, forming a copper dissolving reaction solution (S31), and then the copper dissolving reaction solution (S31) is heated and concentrated to form a copper nitrate concentrate (S32); a copper nitrate crystallization step (S40), wherein the copper nitrate concentrate (S32) is cooled and crystallized, and then subjected to solid-liquid separation to produce a copper nitrate crystal (S42); The first step (S50) involves mixing the copper nitrate crystals (S42), sulfuric acid (52), and copper powder (53) and carrying out the sulfuric acid replacement reaction at a temperature of 25°C to 35°C. The copper powder (53) is used to consume the residual acid and terminate the reaction to form a sulfuric acid replacement reaction slurry (S51). The second step (S70) involves crystallizing the sulfuric acid replacement reaction slurry (S51) and obtaining a primary filtered copper sulfate crystal (S71) through solid-liquid separation.

2. The method for converting copper nitrate to copper sulfate as described in claim 1, wherein, The method for converting copper nitrate to copper sulfate further includes a nitric acid gas recovery step (S60), which involves collecting a nitric acid-containing gas emitted during the sulfuric acid displacement reaction and condensing and recovering the nitric acid-containing gas into liquid nitric acid.

3. The method for converting copper nitrate to copper sulfate as described in claim 1, wherein, The copper sulfate crystallization step (S70) further separates a first filtrate (S72) after solid-liquid separation; the method for converting copper nitrate to copper sulfate further includes a crystallization filtrate recycling step (S90), which involves mixing the first filtrate (S72) with copper powder (92), using the copper powder (92) to consume the residual acid in the first filtrate (S72) to generate a residual acid consumption reaction solution (S91), and returning the residual acid consumption reaction solution (S91) to the copper sulfate crystallization step as an additive during the crystallization operation of the sulfuric acid replacement reaction slurry (S51).

4. The method for converting copper nitrate to copper sulfate as described in claim 3, wherein, The method for converting copper nitrate to copper sulfate further includes a copper sulfate recrystallization step (S80), in which the copper sulfate recrystallization step (S80) involves mixing the initial filtered copper sulfate crystals (S71) with recrystallization water (83) for recrystallization, and then separating the solid and liquid to obtain a copper sulfate crystal product (84) and a second filtrate (S81). The second filtrate (S81) is then sent to the crystallization filtrate reuse step (S90) and mixed with the first filtrate (S72) to generate the residual acid consumption reaction solution (S91) for reuse as a crystallization additive in the copper sulfate crystallization step (S70).

5. The method for converting copper nitrate to copper sulfate as described in claim 4, wherein, The copper sulfate crystal product (84) is copper sulfate pentahydrate (CuSO4·5H2O) with a nitrate nitrogen content of less than or equal to 0.1wt%.

6. The method for converting copper nitrate to copper sulfate as described in claim 1, wherein, Prior to the copper nitrate concentration step (S30), a copper alloy pretreatment step (S10) and an acid leaching step (S20) are further included; wherein, the copper alloy pretreatment step (S10) receives a copper alloy (13) and a degreasing cleaning agent (14), and washes and dehydrates the copper alloy (13) to output a cleaned copper alloy (S11); the acid leaching step (S20) is performed on the cleaned copper alloy (S11) The copper alloy (13) is reacted with an acid leaching solution (23) and a metal salt solution (24) and the copper material (21) are separated. The copper material (21) is provided to the copper nitrate concentration step (S30). The acid leaching solution (23) contains hydrochloric acid with a concentration of 15wt% to 35wt%, and the copper alloy (13) is a waste copper-zinc alloy. The acid leaching treatment step (S20) selectively removes zinc impurities from the waste copper-zinc alloy.

7. The method for converting copper nitrate to copper sulfate as described in claim 1, wherein, The copper nitrate concentration step (S30) is carried out at a heating temperature of 75°C to 85°C to concentrate the copper concentration of the copper nitrate concentrate (S32) to 355 g / L to 367 g / L and to avoid crystallization.

8. The method for converting copper nitrate to copper sulfate as described in claim 1, wherein, The sulfuric acid replacement step (S50) is performed without the need for an external heat source, by using the heat of reaction to maintain the temperature of the sulfuric acid replacement reaction between 25°C and 35°C.

9. A method for converting copper nitrate to copper sulfate as described in claim 1, wherein, The copper powder (53) is added after the sulfuric acid replacement reaction to consume the residual acid and terminate the reaction, thereby promoting the conversion of anhydrous copper sulfate (CuSO4) into copper sulfate pentahydrate (CuSO4·5H2O).

10. A method for converting copper nitrate to copper sulfate as described in claim 1, wherein, After solid-liquid separation in the copper nitrate crystallization step (S40), a copper nitrate crystallization mother liquor (S41) is further separated and returned to the copper nitrate concentration step (S30) for reuse.

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