A method for harmless treatment and resource utilization of fluorine-containing waste residue

Abstract

This invention relates to a method for the harmless treatment and resource utilization of fluorine-containing waste residue, comprising the following steps: (1) adding a leaching solution containing an oxidant and hydrochloric acid dropwise into a leaching column containing fluorine-containing waste residue for cyclic leaching oxidation to obtain crude calcium fluoride; (2) mixing the crude calcium fluoride with calcium peroxide and then calcining to obtain calcium fluoride product. Compared with the prior art, this invention, through cyclic leaching oxidation and mixed calcination, can quickly and effectively remove organic fluorides from waste salt and prepare high-purity calcium fluoride by-products.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a method for the harmless treatment and resource utilization of fluorine-containing waste residue. Background Technology

[0002] The production and use of fluorochemical products generate large amounts of fluoride-containing wastewater, which, after neutralization and precipitation, produces substantial amounts of fluoride-containing waste residue. With increasing demand for fluorochemicals, the amount of fluoride-containing waste residue is also growing rapidly, making its safe treatment and recycling urgent. Most fluoride-containing waste residue contains over 50% calcium fluoride, which can be further purified to produce calcium fluoride byproducts, demonstrating potential for resource utilization. However, several issues exist: firstly, current resource utilization typically involves purifying the waste to a calcium fluoride content of 60-80%, while research on refining fluoride-containing waste residue into acid-grade fluorite powder for the fluorochemical industry chain is relatively limited; secondly, research on the resource utilization of fluoride-containing waste residue mainly focuses on the inorganic fluorochemical field, with less research on fluoride-containing waste residue from the organic fluorochemical industry. The fluoride-containing waste residue from inorganic fluorochemical industries such as photovoltaics and integrated circuits has a relatively simple composition, mainly consisting of CaF2, CaCO3, and SiO2, exhibiting stable properties and low organic content, making resource utilization processes relatively easy. For the organic fluorine chemical industry, in addition to inorganic substances such as CaF2, CaCO3, and SiO2, there are also intermediates and by-products of various fluorine chemicals. These organic fluorides are often difficult to degrade and pose a great threat to the environment and ecology. The vast majority of them are hazardous wastes, which are difficult to treat and pose a high risk of fluoride leaching. Summary of the Invention

[0003] The purpose of this invention is to provide a method for the harmless treatment and resource utilization of fluorine-containing waste residue.

[0004] The objective of this invention can be achieved through the following technical solution: a method for the harmless treatment and resource utilization of fluorine-containing waste residue, comprising the following steps:

[0005] (1) The leaching solution containing oxidant and hydrochloric acid is added dropwise to a leaching column containing fluorine-containing waste residue for cyclic leaching oxidation to obtain crude calcium fluoride;

[0006] (2) The crude calcium fluoride product is mixed with calcium peroxide and then roasted to obtain the calcium fluoride product.

[0007] Preferably, the rinsing solution in step (1) is a mixture of an oxidant and an aqueous hydrochloric acid solution.

[0008] More preferably, the oxidant includes one or more of calcium nitrate and nitric acid.

[0009] More preferably, the oxidant is calcium nitrate, and the mass ratio of calcium nitrate to hydrochloric acid aqueous solution is 1:1 to 30.

[0010] More preferably, the oxidant is nitric acid, and the mass ratio of nitric acid to hydrochloric acid aqueous solution is 1:1 to 50.

[0011] More preferably, the oxidant is a mixture of calcium nitrate and nitric acid, and the mass ratio of calcium nitrate, nitric acid and hydrochloric acid aqueous solution is 1:0.5:1 to 100.

[0012] More preferably, the hydrochloric acid aqueous solution contains 10-37 wt% hydrochloric acid.

[0013] Preferably, the mass of the leaching solution in step (1) is 1 to 5 times the mass of the fluorine-containing waste residue, the leaching rate is 1 ml to 20 ml / s, and the leaching is repeated 1 to 5 times.

[0014] Preferably, the calcium peroxide in step (2) is 0.1-5% of the crude calcium fluoride.

[0015] Preferably, the roasting temperature in step (2) is 400-800℃ and the time is 0.5-5h.

[0016] Preferably, the method for harmless treatment and resource utilization of fluorine-containing waste residue includes the following steps:

[0017] S1: Prepare the leaching solution, which is a mixture of oxidant and hydrochloric acid solution.

[0018] S2: Add fluorine-containing waste residue to the leaching column.

[0019] S3: The prepared leaching solution is slowly added dropwise to the leaching column using a peristaltic pump for cyclic leaching oxidation to obtain crude calcium fluoride.

[0020] S4: After the crude calcium fluoride product undergoes cyclic leaching oxidation treatment, it is mixed with calcium peroxide and then placed in a roasting furnace for high-temperature roasting to prepare high-purity calcium fluoride products as fluorochemical raw materials.

[0021] Preferably, the fluorine-containing waste residue is a solid waste residue produced by neutralization and precipitation of organic wastewater from the synthesis process of fluorine-containing compound precursors, which contains organic fluorides.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The method of the present invention can utilize fluorine-containing waste residue in a high-value manner and purify it to prepare calcium fluoride products of fluorochemical raw material grade;

[0024] 2. This invention uses a combination of cyclic leaching oxidation and high-temperature roasting to remove organic fluorides from fluorine-containing waste residue. After treatment, high-purity calcium fluoride by-products with a purity of over 97% can be obtained, which can be used as acid-grade fluorite concentrate, resulting in higher added value.

[0025] 3. The method of the present invention can quickly and effectively remove organic fluorides from waste salt, reduce harmful factors in waste salt, thereby facilitating the safe utilization of resource products and preparing high-purity calcium fluoride by-products.

[0026] 4. This invention can fix the hydrogen fluoride produced by the decomposition of organofluorine compounds to generate calcium fluoride, thereby further improving the purity of calcium fluoride. Through refining and purification, it can be used as a by-product of calcium fluoride, which is a raw material for fluorochemicals.

[0027] 5. This invention can treat fluorine-containing waste residue from the organofluorine chemical industry. First, the organic components are removed through harmless treatment, and then the residue is refined and purified for resource utilization. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. The fluorine-containing waste residue is generated during the production of hexafluoropropylene, with a moisture content of 52 wt%, a calcium fluoride content (dry basis) of 53.2 wt%, and a total organic matter content (dry basis) of 2.3 wt%.

[0031] The circulating leaching equipment uses a common leaching device, consisting of a leaching column, a leaching liquid collection tank, a leaching liquid recovery pump, a leaching liquid storage tank, and a leaching pump. The leaching liquid in the storage tank is slowly dripped into the leaching column from above by the leaching pump to begin leaching. The leaching liquid flows into the collection tank, and the leaching liquid in the collection tank is returned to the storage tank for reuse by the recovery pump.

[0032] Example 1

[0033] Take 5 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate and 30 wt% hydrochloric acid aqueous solution at a mass ratio of 1:20 to prepare 20 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 5 ml / s. Repeat the leaching process 3 times to obtain crude calcium fluoride.

[0034] Add 100g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 400℃ for 4 hours. After cooling, calcium fluoride by-product 1 can be obtained.

[0035] Example 2

[0036] Take 10 kg of fluorine-containing waste residue and place it in a leaching column. Mix nitric acid and 20 wt% hydrochloric acid aqueous solution at a mass ratio of 1:50 to prepare 30 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 3 ml / s. Repeat the leaching process twice to obtain crude calcium fluoride.

[0037] Add 150g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 600℃ for 2 hours. After cooling, calcium fluoride by-product 2 can be obtained.

[0038] Example 3

[0039] Take 20 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate, nitric acid and 10 wt% hydrochloric acid aqueous solution in a mass ratio of 1:0.5:20 to prepare 100 kg of leaching solution. Slowly add the solution dropwise to the leaching column at 10 ml / s and leach once to obtain crude calcium fluoride.

[0040] Add 300g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 800℃ for 0.5h. After cooling, calcium fluoride by-product 3 can be obtained.

[0041] Example 4

[0042] Take 5 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate and 30 wt% hydrochloric acid aqueous solution at a mass ratio of 1:30 to prepare 20 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 1 ml / s. Repeat the leaching process 5 times to obtain crude calcium fluoride.

[0043] Add 50g of calcium peroxide and crude calcium fluoride, mix evenly, place in a roasting furnace and roast at 500℃ for 3 hours. After cooling, calcium fluoride by-product 4 can be obtained.

[0044] Example 5

[0045] Take 5 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate and 30 wt% hydrochloric acid aqueous solution in a 1:1 mass ratio to prepare 25 kg of leaching solution. Add the solution slowly to the leaching column at 1 ml / s. Repeat the leaching process 5 times to obtain crude calcium fluoride.

[0046] Add 50g of calcium peroxide and crude calcium fluoride, mix evenly, place in a roasting furnace and roast at 500℃ for 2 hours. After cooling, calcium fluoride by-product 5 can be obtained.

[0047] Example 6

[0048] Take 5 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate and 30 wt% hydrochloric acid aqueous solution at a mass ratio of 1:20 to prepare 25 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 20 ml / s. Repeat the leaching process 3 times to obtain crude calcium fluoride.

[0049] Add 50g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 700℃ for 1 hour. After cooling, calcium fluoride by-product 6 can be obtained.

[0050] Example 7

[0051] Take 10 kg of fluorine-containing waste residue and place it in a leaching column. Mix nitric acid and 20 wt% hydrochloric acid aqueous solution at a mass ratio of 1:30 to prepare 20 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 2 ml / s. Repeat the leaching process twice to obtain crude calcium fluoride.

[0052] Add 500g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 600℃ for 2 hours. After cooling, calcium fluoride by-product 7 can be obtained.

[0053] Example 8

[0054] Take 10 kg of fluorine-containing waste residue and place it in a leaching column. Mix nitric acid and 20 wt% hydrochloric acid aqueous solution at a mass ratio of 1:50 to prepare 10 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 1 ml / s. Repeat the leaching process 5 times to obtain crude calcium fluoride.

[0055] Add 500g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 800℃ for 1 hour. After cooling, calcium fluoride by-product 8 can be obtained.

[0056] Example 9

[0057] Take 20 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate, nitric acid and 10 wt% hydrochloric acid aqueous solution in a mass ratio of 1:0.5:10 to prepare 50 kg of leaching solution. Add the solution slowly to the leaching column at a rate of 5 ml / s. Repeat the leaching process twice to obtain crude calcium fluoride.

[0058] Add 100g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 700℃ for 1.5h. After cooling, calcium fluoride by-product 9 can be obtained.

[0059] Example 10

[0060] Take 20 kg of fluorine-containing waste residue and place it in a leaching column. Mix calcium nitrate, nitric acid and 10 wt% hydrochloric acid aqueous solution in a mass ratio of 1:0.5:50 to prepare 80 kg of leaching solution. Add the solution slowly to the leaching column at 10 ml / s and leach it 5 times to obtain crude calcium fluoride.

[0061] Add 200g of calcium peroxide and crude calcium fluoride and mix evenly. Place in a roasting furnace and roast at 500℃ for 2 hours. After cooling, calcium fluoride by-product 10 can be obtained.

[0062] Comparative Example 1

[0063] 20 kg of fluorine-containing waste residue was placed in a leaching column, and 100 kg of water was used as the eluent, which was slowly added dropwise to the leaching column at a rate of 10 ml / s to obtain crude calcium fluoride. The crude product was then placed in a calcining furnace and calcined at 800°C for 0.5 h. After cooling, calcium fluoride byproduct 11 was obtained.

[0064] Comparative Example 2

[0065] 20 kg of fluorine-containing waste residue was placed in a leaching column, and 100 kg of 10 wt% hydrochloric acid aqueous solution was added slowly dropwise to the leaching column at a rate of 10 ml / s to obtain crude calcium fluoride. The crude product was then placed in a calcining furnace and calcined at 800℃ for 0.5 h. After cooling, calcium fluoride byproduct 12 was obtained.

[0066] Comparative Example 3

[0067] 20 kg of fluorine-containing waste residue was placed in a leaching column, and 100 kg of 10 wt% hydrochloric acid aqueous solution was added slowly dropwise to the leaching column at a rate of 10 ml / s. The leaching was repeated once to obtain crude calcium fluoride. The crude product was then placed in a calcining furnace and calcined at 800℃ for 0.5 h. After cooling, calcium fluoride by-product 13 was obtained.

[0068] Comparative Example 4

[0069] 20 kg of fluorine-containing waste residue was placed in a leaching column, and 100 kg of 10 wt% hydrochloric acid aqueous solution was added slowly dropwise to the leaching column at a rate of 10 ml / s. The leaching was repeated once to obtain crude calcium fluoride. 300 g of calcium oxide was added and mixed evenly with the crude calcium fluoride. The mixture was then placed in a calcining furnace and calcined at 800 °C for 0.5 h. After cooling, calcium fluoride by-product 14 was obtained.

[0070] Comparative Example 5

[0071] 20 kg of fluorine-containing waste residue was placed in a leaching column, and 100 kg of 10 wt% hydrochloric acid aqueous solution was added slowly dropwise to the leaching column at a rate of 10 ml / s. The leaching was repeated once to obtain crude calcium fluoride. 300 g of calcium peroxide was added and mixed evenly with the crude calcium fluoride. The mixture was then placed in a calcining furnace and calcined at 800°C for 0.5 h. After cooling, calcium fluoride by-product 15 was obtained.

[0072] The quality of calcium fluoride by-products was determined in accordance with the national standard GB / T 5195.1-2017 "Determination of Calcium Fluoride Content in Fluorite by EDTA Titration and Distillation-Voltage Titration". The relevant data are shown in Table 1. In the relevant examples, the purity of calcium fluoride index is greater than 97%, and the calcium fluoride content meets the Grade I quality standard in GB 8216-87 "Fluorite Ore".

[0073] Table 1. Calcium Fluoride Product Testing

[0074]

[0075]

[0076] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for the harmless treatment and resource utilization of fluorine-containing waste residue, characterized in that, Includes the following steps: (1) The leaching solution containing oxidant and hydrochloric acid is added dropwise to a leaching column containing fluorine-containing waste residue for cyclic leaching oxidation to obtain crude calcium fluoride; (2) The crude calcium fluoride product is mixed with calcium peroxide and then roasted to obtain the calcium fluoride product.

2. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 1, characterized in that, The rinsing solution in step (1) is a mixture of an oxidant and an aqueous hydrochloric acid solution.

3. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 2, characterized in that, The oxidizing agent includes one or more of calcium nitrate and nitric acid.

4. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 3, characterized in that, The oxidant is calcium nitrate, and the mass ratio of calcium nitrate to hydrochloric acid aqueous solution is 1:1 to 30.

5. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 3, characterized in that, The oxidant is nitric acid, and the mass ratio of nitric acid to hydrochloric acid aqueous solution is 1:1 to 50.

6. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 3, characterized in that, The oxidant is a mixture of calcium nitrate and nitric acid, and the mass ratio of calcium nitrate, nitric acid and hydrochloric acid aqueous solution is 1:0.5:1 to 100.

7. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 2, characterized in that, The hydrochloric acid aqueous solution contains 10–37 wt% hydrochloric acid.

8. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 1, characterized in that, The mass of the leaching solution in step (1) is 1 to 5 times the mass of the fluorine-containing waste residue, the leaching rate is 1 ml to 20 ml / s, and the leaching is repeated 1 to 5 times.

9. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 1, characterized in that, The calcium peroxide mentioned in step (2) is 0.1-5% of the crude calcium fluoride.

10. The method for harmless treatment and resource utilization of fluorine-containing waste residue according to claim 1, characterized in that, The roasting temperature in step (2) is 400-800℃ and the time is 0.5-5h.

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