A recovery and treatment process for non-fluorine-containing waste acid solution and the product obtained by recovery

Abstract

This application relates to the technical field of waste acid liquid treatment, and specifically discloses a non-fluorine-containing waste acid liquid recovery and treatment process and the products obtained by the recovery. The treatment process includes the following operating steps: (1) Hydrogen peroxide and sodium hydroxide are successively added to the waste acid liquid, and then filtered. The filter residue A is iron hydroxide; (2) Sodium hydroxide is added to the filtrate A, and then filtered. The filtrate C is collected, hydrochloric acid is added, and then heated. The solid is collected to obtain sodium chloride; (3) Hydrochloric acid is added to the filter residue C, stirred, sulfuric acid is added, and then filtered. The filtrate G and the filter residue G are collected. The filter residue G is calcium sulfate; (4) The filtrate G is heated, and hydrogen chloride gas is absorbed to obtain hydrochloric acid; (5) The mixed solution I is heated, and the solid is collected to obtain magnesium sulfate. The purities of iron hydroxide, sodium chloride, calcium sulfate, and magnesium sulfate recovered from the non-fluorine-containing waste acid liquid in this application and the concentration of the hydrochloric acid solution are 98.8%, 99.0%, 98.51%, 98.71%, and 36.96% respectively.

Description

Technical Field

[0001] This application relates to the field of waste acid liquid treatment, and more specifically, to a recovery treatment process for non-fluorine-containing waste acid liquid and the products obtained by recovery. Background Art

[0002] Tailings are the products of the beneficiation operation in ore dressing, which are the parts with low content of target components in the products and cannot be applied to production. Although the content of target components in tailings is low, there is still economic value in further recycling the target components. Recycling tailings comprehensively is the need to make full use of mineral resources and protect the ecological environment. In the process of comprehensively recycling tailings to produce quartz concentrate, waste acid liquid containing calcium ions, magnesium ions, ferrous ions, ferric ions and chloride ions will be generated.

[0003] In the related technology, in order to avoid environmental pollution caused by discharging waste acid liquid, alkaline substances such as lime, carbide slag and calcium hydroxide are usually used to carry out neutralization reaction on the waste acid liquid and then directly discharge it. This treatment method of waste acid liquid will not only cause problems such as difficult sludge dewatering, difficult drying and large post-treatment difficulty, but also this method ignores various component resources in the waste acid liquid, resulting in low recovery rate of the waste acid liquid, low production profit of recovery and utilization, and unable to make up for the increased production cost required for treating non-fluorine-containing waste acid liquid. Summary of the Invention

[0004] In order to improve the recovery rate of waste acid liquid and make up for the increased production cost required for treating non-fluorine-containing waste acid liquid, this application provides a recovery treatment process for non-fluorine-containing waste acid liquid and the products obtained by recovery.

[0005] In the first aspect, this application provides a recovery treatment process for non-fluorine-containing waste acid liquid, and its technical solution is as follows: a recovery treatment process for non-fluorine-containing waste acid liquid, the non-fluorine-containing waste acid liquid is an acidic liquid containing calcium ions, magnesium ions, ferrous ions, ferric ions and chloride ions, and it includes the following operation steps:

[0006] (1) Add sufficient hydrogen peroxide solution to the waste acid liquid to oxidize ferrous ions to ferric ions, add sodium hydroxide solution during stirring, adjust the pH of the solution to neutral, let it stand, filter, and collect filtrate A and filter residue A; Filter residue A is iron hydroxide, and filtrate A containing calcium ions, magnesium ions, chloride ions and sodium ions enters the next process;

[0007] (2) Add sodium hydroxide solution to filtrate A, adjust the pH of the solution to medium strong alkalinity to obtain hydrolysis liquid B, let it stand, filter, and collect filtrate C and filter residue C; Filter residue C is a mixture of calcium hydroxide and magnesium hydroxide; Add dilute hydrochloric acid to filtrate C, adjust the pH of the solution to neutral, heat and evaporate the internal water, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0008] (3) Add dilute hydrochloric acid solution to the above-mentioned filter residue C, and adjust it to neutral pH under stirring; add sulfuric acid with a molar concentration at the stoichiometric point of 9 mol / L to precipitate calcium ions, let it stand, filter, and collect filtrate G and filter residue G. Filter residue G is calcium sulfate; the acidic filtrate G containing magnesium ions, sulfate ions and chloride ions then enters the next process.

[0009] (4) Under a stirring speed of 30 - 60 r / min, heat filtrate G at 60 - 80 °C until no hydrogen chloride gas is produced. Absorb hydrogen chloride gas with deionized water during the heating process to obtain a high-purity hydrochloric acid solution product. The remaining mixed solution I containing magnesium ions and sulfate ions then enters the next process.

[0010] (5) Heat and evaporate the internal water of the above-mentioned mixed solution I, collect the solid, and obtain magnesium sulfate product.

[0011] By adopting the above technical solution, add hydrogen peroxide solution to the waste acid solution to oxidize ferrous ions in the waste acid solution to ferric ions, add sodium hydroxide to adjust the pH of the solution to neutral, completely hydrolyze the ferric ions in the waste acid solution to obtain ferric hydroxide precipitate, filter, and obtain ferric hydroxide product. Sodium hydroxide reacts with hydrochloric acid to form sodium chloride, thus obtaining filtrate A containing calcium ions, magnesium ions, chloride ions and sodium ions. Filtrate A then enters the next process.

[0012] Add sodium hydroxide to filtrate A containing calcium ions, magnesium ions, chloride ions and sodium ions, adjust the pH of the solution to moderately strong alkalinity, completely hydrolyze calcium ions and magnesium ions to form filter residue C of calcium hydroxide precipitate and magnesium hydroxide precipitate and filtrate C containing sodium chloride and sodium hydroxide. Add dilute hydrochloric acid to filtrate C containing sodium chloride and sodium hydroxide to adjust the pH of the solution to neutral, make the sodium hydroxide in filtrate C react with hydrochloric acid to form sodium chloride, and thus obtain sodium chloride product by heating and evaporating the internal water. Filter residue C containing calcium hydroxide precipitate and magnesium hydroxide precipitate then enters the next process.

[0013] Add dilute hydrochloric acid to filter residue C, adjust the solution to neutral, dissolve filter residue C, and the reaction generates calcium chloride and magnesium chloride. Subsequently, add a sufficient amount of dilute sulfuric acid solution at the stoichiometric point to make calcium chloride and magnesium chloride in the solution react with sulfuric acid to form calcium sulfate, magnesium sulfate and hydrochloric acid. Calcium sulfate is insoluble in water, so it exists in the solution in solid form. Filter, and calcium sulfate product can be obtained. And filtrate G containing magnesium ions, sulfate ions and chloride ions then enters the next process;

[0014] Heat filtrate G containing magnesium sulfate and hydrochloric acid to produce hydrogen chloride gas. Absorb hydrogen chloride gas with water during the heating process to obtain a high-purity hydrochloric acid solution product. The remaining mixed solution I containing magnesium ions and sulfate ions then enters the next process.

[0015] Continue to heat and evaporate the internal water mixture I. After all the water in the mixture I is evaporated, magnesium sulfate product is obtained.

[0016] Preferably: in the step (1), the volume ratio of the hydrogen peroxide solution to the waste acid solution is 1:(15 - 30).

[0017] By adopting the above technical solution, adjusting the volume ratio between hydrogen peroxide and the waste acid solution can fully oxidize all the divalent iron ions in the waste acid solution into trivalent iron ions.

[0018] Preferably: in the step (1), the sodium hydroxide solution is added at a flow rate of 10 - 50 L / min.

[0019] Preferably: in the step (1), first add the sodium hydroxide solution at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 5; then add the sodium hydroxide solution at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7;

[0020] Or / and in the step (2), first add the sodium hydroxide solution at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 11; then add the sodium hydroxide solution at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 12.5.

[0021] By adopting the above technical solution, in the step (1), when the pH of the waste acid solution ≤ 5, the flow rate of sodium hydroxide is controlled at 40 - 60 L / min, and the flow rate is relatively fast. And the higher flow rate has a better disturbance effect on the solution, thus accelerating the hydrolysis of iron ions, reducing the stirring time and lowering the production cost. When 5 < pH of the waste acid solution ≤ 7, the flow rate of sodium hydroxide is controlled at about 10 L / min, and the flow rate becomes slower. On the one hand, it is easier to control the pH of the solution, and on the other hand, it makes the hydrolysis of iron ions more sufficient.

[0022] In the step (2), when the pH of the waste acid solution ≤ 11, the flow rate of sodium hydroxide is controlled at 40 - 60 L / min, and the flow rate is relatively fast. And the higher flow rate has a better disturbance effect on the solution, thus accelerating the hydrolysis of calcium ions and magnesium ions, reducing the stirring time and lowering the production cost. When 11 < pH of the waste acid solution ≤ 12.5, the flow rate of sodium hydroxide is controlled at about 10 L / min, and the flow rate becomes slower. On the one hand, it is easier to control the pH of the solution, and on the other hand, it makes the hydrolysis of calcium ions and magnesium ions more sufficient.

[0023] Preferably: in the step (3), the dilute sulfuric acid is added at a flow rate of 23 - 27 L / min.

[0024] By adopting the above technical solution, the flow rate of the sulfuric acid solution is controlled at 23 - 27 L / min, enabling calcium chloride and sulfuric acid, magnesium chloride and sulfuric acid to react sufficiently.

[0025] Preferably: in the step (2), first add dilute hydrochloric acid at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 9; then add dilute hydrochloric acid at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7.

[0026] Or / and in the step (3), first add dilute hydrochloric acid at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 5; then add dilute hydrochloric acid at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7.

[0027] By adopting the above technical solution, in step (2), when the pH of the waste acid solution ≥ 9, the flow rate of dilute hydrochloric acid is controlled at 40 - 60 L / min. The flow rate is relatively fast, and a higher flow rate has a better disturbance effect on the solution, thereby accelerating the chemical reaction between sodium hydroxide and hydrochloric acid, reducing the stirring time, and lowering the production cost. When 7 < pH ≤ 9 of the waste acid solution, the flow rate of dilute hydrochloric acid is controlled at about 10 L / min. The flow rate becomes slower. On the one hand, it is easier to control the pH of the solution, and on the other hand, the reaction between sodium hydroxide and hydrochloric acid is more complete.

[0028] In step (3), when the pH of the waste acid solution ≤ 5, the flow rate of the dilute hydrochloric acid solution is controlled at 40 - 60 L / min. The flow rate is relatively fast, and a higher flow rate has a better disturbance effect on the solution, thereby accelerating the acid dissolution of calcium hydroxide and magnesium hydroxide precipitates, reacting to form calcium chloride and magnesium chloride, reducing the stirring time, and lowering the production cost. When 5 < pH ≤ 7 of the waste acid solution, the flow rate of the dilute hydrochloric acid solution is controlled at about 10 L / min. The flow rate becomes slower. On the one hand, it is easier to control the pH of the solution, and on the other hand, the acid dissolution of calcium hydroxide and magnesium hydroxide precipitates is more complete.

[0029] Preferably: in the step (1), wash the filter residue A with clear water, stop washing when the conductivity of the washing water A reaches the same as that of the clear water used for washing, collect the washing water A, and after the filter residue A is washed and purified with clear water, obtain the filter residue B, collect the filter residue B, and the filter residue B is the purified iron hydroxide product; the washing water A enters the next process together with the filtrate A.

[0030] By adopting the above technical solution, in step (1), the iron hydroxide precipitate is washed with clear water, and the collected solid is the iron hydroxide product. By washing, impurities in the form of particles or soluble in water in the iron hydroxide precipitate can be washed away, ensuring the purity and quality of the iron hydroxide product.

[0031] Preferably, in step (2), before adding dilute hydrochloric acid to the filter residue C, the filter residue C is rinsed first. The rinsing is stopped when the pH of the rinsing water B reaches 6-7. The rinsing water B is collected. The filter residue C is rinsed and purified with clear water to obtain a filter residue D, and the filter residue D is collected, which is a mixture of purified calcium hydroxide and magnesium hydroxide. After mixing the rinsing water B and the filtrate C, dilute hydrochloric acid is added for the remaining operations.

[0032] By adopting the above technical solution, in step (2), the calcium hydroxide and magnesium hydroxide precipitates are rinsed with clear water, and the collected solid is a mixture of calcium hydroxide and magnesium hydroxide. By rinsing, the sodium hydroxide and other impurities in ionic form and soluble in water mixed in the calcium hydroxide and magnesium hydroxide precipitates can be washed away, ensuring the purity and quality of the calcium hydroxide and magnesium hydroxide products.

[0033] Preferably, in step (3), the filter residue G is rinsed. The rinsing is stopped when the pH of the rinsing water C reaches 6-7. The filter residue G is rinsed and purified with clear water to obtain a filter residue H. The filter residue H and the rinsing water C are collected. The filter residue H is the purified calcium sulfate product, and the rinsing water C enters the next process together with the filtrate G.

[0034] By adopting the above technical solution, in step (3), the calcium sulfate precipitate is rinsed with clear water, and the collected solid is the calcium sulfate product. By rinsing, the dilute hydrochloric acid and other impurities in ionic form and soluble in water mixed in the calcium sulfate precipitate can be washed away, ensuring the purity and quality of the calcium sulfate product.

[0035] In a second aspect, the present application provides a product obtained by recycling and treating the above non-fluoride waste acid solution.

[0036] In summary, the present application includes at least one of the following beneficial technical effects:

[0037] (1) By controlling the flow rate of the sodium hydroxide solution to be fast first and then slow when the pH of the waste acid solution is not greater than 5 and greater than 5, the recovery rate of iron ions is 99.40%, the purity of the recovered iron hydroxide is 98.8%, and the quality of the obtained iron hydroxide is relatively good, with a high recovery and utilization rate.

[0038] (2) By controlling the flow rate of the sodium hydroxide solution to be fast first and then slow when the pH of the waste acid solution is less than 11 and not greater than 12.5, and at the same time controlling the flow rate of the added dilute hydrochloric acid solution to be fast first and then slow, the purity of the recovered sodium chloride is 99.0%, and the quality of the obtained sodium chloride is relatively good, with a high recovery and utilization rate.

[0039] (3) By controlling the flow rate of the dilute hydrochloric acid solution to be fast first and then slow when the pH of the waste acid solution is not greater than 5 and greater than 5, the recovery rate of calcium ions is 99.05%, the purity of the recovered calcium sulfate is 98.51%, and the quality of the obtained calcium sulfate is relatively good, with a high recovery and utilization rate.

[0040] (4) Experiments have proved that in step (2), when using dilute hydrochloric acid with a concentration of 1 mol / L to dissolve calcium hydroxide and magnesium hydroxide solids, even when the flow rate is 40 - 60 L / min, the temperature of the local solution in the upper layer of the solution will not rise sharply to cause boiling, and the solution containing calcium hydroxide and magnesium hydroxide solids will not splash onto the inner wall of the equipment and the stirrer. All the calcium hydroxide and magnesium hydroxide solids in the solution can be dissolved.

[0041] (5) Tests have proved that when adding dilute sulfuric acid in step (3), controlling the flow rate of the dilute sulfuric acid at 23 - 27 L / min can prevent the excessive impurities adsorbed and wrapped inside the calcium sulfate precipitate due to the too high local concentration in the solution during the precipitation of calcium sulfate in the decomposition liquid B, thus improving the purity of calcium sulfate. At the same time, it can also make calcium chloride and sulfuric acid react completely to obtain high-purity calcium sulfate products.

[0042] (6) Tests have proved that in steps (1), (2), and (3), the precipitate obtained after standing the solution for a period of time after precipitation has a larger particle size and higher purity than the freshly formed precipitate.

[0043] (7) Tests of this application have proved that the particle size of the precipitate (particle size ≥ 19 μm) of the waste acid solution after the hydrolysis of iron ions, the hydrolysis liquid B after the hydrolysis of calcium and magnesium, and the precipitate after adding a precipitant to the solution and standing for a period of time is ≥ 2.8 times larger than that of the freshly formed precipitate (particle size ≤ 5 μm) and has higher purity.

[0044] (8) This application heats the filtrate G and the washing water C by sub-boiling distillation at a temperature of 60 - 80 °C. The recovery rate of chloride ions is 98.57%, the concentration of the recovered high-purity hydrochloric acid is 36.96%, and the purity reaches the purity level of chemical reagents. The obtained hydrochloric acid has excellent quality and high recovery and utilization rate.

[0045] (9) This application controls the evaporation of internal moisture by heating. The recovery rate of magnesium ions is 99.47%, the purity of the recovered magnesium sulfate is 98.71%, and the obtained magnesium sulfate has relatively good quality and high recovery and utilization rate. Specific Embodiments

[0046] The following further elaborates on this application in detail with specific embodiments.

[0047] The process of this application is described below with specific embodiments. Among them, the content of elements or compounds in the non-fluoride-containing waste acid liquid in each embodiment of this application is specifically: the concentration of iron ions is 32.235 g / L, the concentration of magnesium ions is 13.290 g / L, and the concentration of calcium ions is 18.985 g / L.

[0048] Example 1

[0049] A recovery and treatment process for non-fluorinated waste acid solution, comprising the following operating steps:

[0050] (1) Add 400 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution to oxidize ferrous ions to ferric ions, stir for 10 min, and then, under stirring conditions, first add sodium hydroxide solution with a molar concentration of 5 mol / L at a flow rate of 50 L / min to adjust the pH of the solution to 5, and then add sodium hydroxide solution with a molar concentration of 5 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7. Let it stand for 15 min, filter to obtain filtrate A and filter residue A respectively, and collect filtrate A and filter residue A; rinse filter residue A with clear water, stop rinsing after the conductivity of rinsing water A reaches the same as that of the clear water used for rinsing, collect rinsing water A, and obtain filter residue B after purifying filter residue A by rinsing with clear water. Collect filter residue B. Filter residue B is the iron hydroxide product. Filtrate A and rinsing water A containing calcium ions, magnesium ions, chloride ions and sodium ions enter the next process; (2) Under stirring, first add sodium hydroxide solution with a molar concentration of 5 mol / L to the mixed solution of filtrate A and rinsing water A at a flow rate of 50 L / min to adjust the pH of the solution to 11, and then add sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min to adjust the pH of the solution to 12.5 to obtain hydrolysis solution B. Filter to obtain filtrate C and filter residue C respectively, and collect filtrate C and filter residue C; rinse filter residue C with clear water, stop rinsing after the pH of rinsing water B reaches 7, collect rinsing water B, and obtain filter residue D after purifying filter residue C by rinsing with clear water. Collect filter residue D. Mix rinsing water B and filtrate C evenly to obtain mixed solution E; under stirring, first add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 50 L / min to adjust the pH of the solution to 9, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min to adjust the pH of the solution to 7. Heat and evaporate the internal water, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0051] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above-mentioned filter residue C at a flow rate of 50 L / min to adjust the solution pH to 5, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L at a flow rate of 10 L / min to adjust the solution pH to 7 until the filter residue C is completely dissolved; then add 1133.864 L of sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 25 L / min to precipitate calcium ions, filter, and obtain filtrate G and filter residue G respectively. Collect filtrate G and filter residue G, wash the filter residue G with clear water, stop washing when the pH of the washing water C reaches 6 - 7, collect the washing water C, and after washing and purifying the filter residue G with clear water, obtain filter residue H. Collect filter residue H, and filter residue H is the calcium sulfate product; the acidic filtrate G containing magnesium ions, sulfate ions, and chloride ions and the washing water C enter the next process;

[0052] (4) Under the conditions of a stirring speed of 45 r / min and 80 °C, heat the mixed solution of filtrate G and washing water C until no hydrogen chloride gas is produced. Absorb hydrogen chloride gas with deionized water during the heating process to obtain a high-purity hydrochloric acid solution product, and the remaining mixed solution I containing magnesium ions and sulfate ions enters the next process;

[0053] (5) Under the condition of 100 °C, heat and evaporate the internal water of the above-mentioned mixed solution I, collect the solid, and obtain magnesium sulfate product.

[0054] Example 2

[0055] A recovery and treatment process for non-fluorine-containing waste acid solution, including the following operating steps:

[0056] 1. Add 400 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution to oxidize ferrous ions to ferric ions, stir for 10 min, and then, under stirring conditions, first add sodium hydroxide solution with a molar concentration of 5 mol / L at a flow rate of 50 L / min to adjust the solution pH to 5, and then add sodium hydroxide solution with a molar concentration of 5 mol / L at a flow rate of 10 L / min to adjust the solution pH to 7. Let it stand for 15 min, filter, and obtain filtrate A and filter residue A respectively. Collect filtrate A and filter residue A, and filter residue A is the iron hydroxide product. The filtrate A containing calcium ions, magnesium ions, chloride ions, and sodium ions enters the next process;

[0057] (2) While stirring, first add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 50 L / min to adjust the pH of the solution to 11. Then, add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min to adjust the pH of the solution to 12.5, obtaining hydrolysis solution B. Filter to obtain filtrate C and filter residue C respectively. Collect filtrate C and filter residue C. While stirring, first add dilute hydrochloric acid with a molar concentration of 1 mol / L to filtrate C at a flow rate of 50 L / min to adjust the pH of the solution to 9. Then, add dilute hydrochloric acid with a molar concentration of 1 mol / L to filtrate C at a flow rate of 10 L / min to adjust the pH of the solution to 7. Heat to evaporate the internal moisture and collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0058] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above filter residue C at a flow rate of 50 L / min to adjust the pH of the solution to 5, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7 until filter residue C is completely dissolved; Then add 1133.864 L of sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 25 L / min to precipitate calcium ions. Filter to obtain filtrate G and filter residue G respectively. Collect filtrate G and filter residue G. Filter residue G is the calcium sulfate product; The acidic filtrate G containing magnesium ions, sulfate ions and chloride ions enters the next process;

[0059] (4) Under the conditions of a stirring speed of 45 r / min and 80 °C, heat filtrate G until no hydrogen chloride gas is produced. Absorb hydrogen chloride gas with deionized water during the heating process to obtain hydrochloric acid solution product, and the remaining mixed solution J containing magnesium sulfate enters the next process;

[0060] (5) The same as Example 1 to obtain magnesium sulfate product.

[0061] Example 3

[0062] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0063] (1) The same as Example 2 to obtain iron hydroxide product;

[0064] (2) The same as Example 2 to obtain sodium chloride product;

[0065] (3) The same as Example 1 to obtain calcium sulfate product;

[0066] (4) The same as Example 2 to obtain hydrochloric acid solution product;

[0067] (5) The same as Example 1 to obtain magnesium sulfate product.

[0068] Example 4

[0069] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0070] (1) The same as Example 2 to obtain ferric hydroxide product;

[0071] (2) The same as Example 1 to obtain sodium chloride product;

[0072] (3) The same as Example 1 to obtain calcium sulfate product;

[0073] (4) The same as Example 1 to obtain hydrochloric acid solution product;

[0074] (5) The same as Example 1 to obtain magnesium sulfate product.

[0075] Example 5

[0076] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0077] (1) Add 700 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution, stir for 10 min, and add sodium hydroxide with a molar concentration of 5 mol / L at a flow rate of 50 L / min under stirring to adjust the pH of the solution to 5, then add sodium hydroxide with a molar concentration of 5 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7. The remaining operations are the same as those in Example 1 to obtain ferric hydroxide product;

[0078] (2) The same as Example 1 to obtain sodium chloride product;

[0079] (3) The same as Example 1 to obtain calcium sulfate product;

[0080] (4) The same as Example 1 to obtain hydrochloric acid solution product;

[0081] (5) The same as Example 1 to obtain magnesium sulfate product.

[0082] Example 6

[0083] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0084] (1) Add 300 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution, stir for 10 min, and first add sodium hydroxide with a molar concentration of 5 mol / L at a flow rate of 50 L / min under stirring to adjust the pH of the solution to 5, then add sodium hydroxide with a molar concentration of 5 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7. The remaining operations are the same as those in Example 1 to obtain ferric hydroxide product;

[0085] (2) The same as Example 1 to obtain sodium chloride product;

[0086] (3) Similar to Example 1, calcium sulfate product is obtained;

[0087] (4) Similar to Example 1, hydrochloric acid solution product is obtained;

[0088] (5) Similar to Example 1, magnesium sulfate product is obtained.

[0089] Example 7

[0090] A recovery and treatment process for non-fluoride-containing waste acid solution, comprising the following operating steps:

[0091] (1) Add 400 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution, stir for 10 min, and add sodium hydroxide with a molar concentration of 5 mol / L at a flow rate of 50 L / min under stirring to adjust the pH of the solution to 7. The remaining operations are the same as in Example 1 to obtain iron hydroxide product;

[0092] (2) Similar to Example 1, sodium chloride product is obtained;

[0093] (3) Similar to Example 1, calcium sulfate product is obtained;

[0094] (4) Similar to Example 1, hydrochloric acid solution product is obtained;

[0095] (5) Similar to Example 1, magnesium sulfate product is obtained.

[0096] Example 8

[0097] A recovery and treatment process for non-fluoride-containing waste acid solution, comprising the following operating steps:

[0098] (1) Similar to Example 1, iron hydroxide product is obtained;

[0099] (2) Mix rinsing water A and filtrate A evenly, add sodium hydroxide at a flow rate of 50 L / min under stirring to adjust the pH of the solution to 12.5. The remaining operations are the same as in Example 1 to obtain sodium chloride product;

[0100] (3) Similar to Example 1, calcium sulfate product is obtained;

[0101] (4) Similar to Example 1, hydrochloric acid solution product is obtained;

[0102] (5) Similar to Example 1, magnesium sulfate product is obtained.

[0103] Example 9

[0104] A recovery and treatment process for non-fluoride-containing waste acid solution, comprising the following operating steps:

[0105] (1) Similar to Example 1, iron hydroxide product is obtained;

[0106] (2) Mix the leaching water A and the filtrate A evenly. While stirring, first add sodium hydroxide at a flow rate of 50 L / min to adjust the pH of the solution to 11; then add sodium hydroxide at a flow rate of 10 L / min to adjust the pH of the solution to 12.5. Hydrolyze the filtrate A and the leaching water A to obtain the hydrolyzate B. Filter and collect the filtrate C and the filter residue C. Wash the filter residue C with clear water. Stop washing when the pH of the leaching water B reaches 6 - 7. Collect the leaching water B, filter, and collect the filter residue D. Mix the leaching water B and the filtrate C evenly to obtain the mixed solution E. Stir the above mixed solution E and add dilute hydrochloric acid with a molar concentration of 1 mol / L at a flow rate of 50 L / min to adjust the pH of the solution to 7. The remaining operations are the same as in Example 1 to obtain sodium chloride products;

[0107] (3) The same as Example 1 to obtain calcium sulfate products;

[0108] (4) The same as Example 1 to obtain hydrochloric acid solution products;

[0109] (5) The same as Example 1 to obtain magnesium sulfate products.

[0110] Example 10

[0111] A recovery and treatment process for non - fluorine - containing waste acid solution, including the following operating steps:

[0112] (1) The same as Example 1 to obtain iron hydroxide products;

[0113] (2) The same as Example 1 to obtain sodium chloride products;

[0114] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above filter residue C at a flow rate of 50 L / min to adjust the pH of the solution to 7. The remaining operations are the same as in Example 1 to obtain calcium sulfate products;

[0115] (4) The same as Example 1 to obtain hydrochloric acid solution products;

[0116] (5) The same as Example 1 to obtain magnesium sulfate products.

[0117] Example 11

[0118] A recovery and treatment process for non - fluorine - containing waste acid solution, including the following operating steps:

[0119] (1) Add 400 L of hydrogen peroxide solution with a mass fraction of 30% to 10000 L of waste acid solution to oxidize ferrous ions to ferric ions, stir for 10 min, and then add sodium hydroxide solution with a molar concentration of 5 mol / L at a flow rate of 10 L / min under stirring conditions to adjust the pH of the solution to 7. The remaining operations are the same as in Example 1 to obtain iron hydroxide products;

[0120] (2) While stirring, add sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min, adjust the pH of the solution to 12.5 to obtain hydrolysis solution B, filter, and collect filtrate C and filter residue C; rinse filter residue C with clear water, stop rinsing when the pH of rinsing water D reaches 7, collect rinsing water D, filter, and collect filter residue D. Mix rinsing water D and filtrate C evenly to obtain mixed solution E; while stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min, adjust the pH of the solution to 7, heat to evaporate the internal water, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0121] (3) While stirring, add sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min, adjust the pH of the solution to 12.5 to obtain hydrolysis solution B, filter, and collect filtrate C and filter residue C; rinse filter residue C with clear water, stop rinsing when the pH of rinsing water D reaches 7, collect rinsing water D, filter, and collect filter residue D. Mix rinsing water D and filtrate C evenly to obtain mixed solution E; while stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min, adjust the pH of the solution to 7, heat to evaporate the internal water, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0122] (4) Same as Example 1, to obtain hydrochloric acid solution product;

[0123] (5) Same as Example 1, to obtain magnesium sulfate product.

[0124] Example 12

[0125] A recovery and treatment process for non-fluorine-containing waste acid solution, including the following operating steps:

[0126] (1) Same as Example 1, to obtain iron hydroxide product;

[0127] (2) Same as Example 1, to obtain sodium chloride product;

[0128] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above filter residue C at a flow rate of 50 L / min to adjust the pH of the solution to 5, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7 until filter residue C is completely dissolved; then add 1133.864 L of dilute sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 30 L / min to precipitate calcium ions, filter, and collect filtrate G and filter residue G. Rinse filter residue G with clear water, stop rinsing when the pH of rinsing water C reaches 6 - 7, collect rinsing water C, filter, and collect filter residue H. Filter residue H is the calcium sulfate product; the acidic filtrate G containing magnesium ions, sulfate ions, and chloride ions enters the next process;

[0129] (4) Similar to Example 1, a hydrochloric acid solution product is obtained;

[0130] (5) Similar to Example 1, a magnesium sulfate product is obtained.

[0131] Example 13

[0132] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0133] (1) Similar to Example 1, an iron hydroxide product is obtained;

[0134] (2) While stirring, first add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 50 L / min to adjust the solution pH to 11, and then add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min to adjust the solution pH to 12.5 to obtain hydrolysis solution B. Filter it to collect filtrate C and filter residue C; rinse filter residue C with clear water, stop rinsing when the pH of rinsing water D reaches 7, collect rinsing water D, filter it to collect filter residue D, mix rinsing water D and filtrate C evenly to obtain mixed solution E; while stirring, first add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 50 L / min to adjust the solution pH to 9, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min to adjust the solution pH to 7. Heat and evaporate the internal water, collect the solid to obtain a sodium chloride product, and filter residue C enters the next process;

[0135] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above-mentioned filter residue C at a flow rate of 60 L / min to adjust the solution pH to 7 until filter residue C is completely dissolved; add 1133.864 L of dilute sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 25 L / min to precipitate calcium ions, filter it to collect filtrate G and filter residue G, rinse filter residue G with clear water, stop rinsing when the pH of rinsing water C reaches 6 - 7, collect rinsing water C, filter it to collect filter residue H, and filter residue H is the calcium sulfate product; the acidic filtrate G containing magnesium ions, sulfate ions and chloride ions enters the next process;

[0136] (4) Similar to Example 1, a hydrochloric acid solution product is obtained;

[0137] (5) Similar to Example 1, a magnesium sulfate product is obtained.

[0138] Example 14

[0139] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0140] (1) Similar to Example 1, an iron hydroxide product is obtained;

[0141] (2) While stirring, first add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 50 L / min to adjust the pH of the solution to 11, and then add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min to adjust the pH of the solution to 12.5, obtaining hydrolysis solution B. Filter and collect filtrate C and filter residue C; rinse filter residue C with clear water and stop rinsing when the pH of the rinsing water D reaches 7. Collect rinsing water D, filter and collect filter residue D. Mix rinsing water D and filtrate C evenly to obtain mixed solution E; while stirring, first add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 50 L / min to adjust the pH of the solution to 9, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min to adjust the pH of the solution to 7. Heat and evaporate the internal water, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0142] (3) While stirring, add dilute hydrochloric acid with a molar concentration of 1 mol / L to the above-mentioned filter residue C at a flow rate of 50 L / min to adjust the pH of the solution to 5, and then add dilute hydrochloric acid with a molar concentration of 1 mol / L at a flow rate of 10 L / min to adjust the pH of the solution to 7 until filter residue C is completely dissolved; then add 1100.0 L of dilute sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 25 L / min to precipitate calcium ions, and the remaining operations are the same as in Example 1 to obtain calcium sulfate product;

[0143] (4) The same as in Example 1 to obtain hydrochloric acid solution product;

[0144] (5) The same as in Example 1 to obtain magnesium sulfate product.

[0145] Example 15

[0146] A recovery and treatment process for non-fluorine-containing waste acid solution, comprising the following operating steps:

[0147] (1) The same as in Example 1 to obtain iron hydroxide product;

[0148] (2) While stirring, first add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 50 L / min to adjust the pH of the solution to 11, and then add a sodium hydroxide solution with a molar concentration of 5 mol / L to filtrate A at a flow rate of 10 L / min to adjust the pH of the solution to 12.5, obtaining hydrolysis solution B. Filter it to collect filtrate C and filter residue C; rinse filter residue C with clear water, stop rinsing when the pH of rinsing water D reaches 7, collect rinsing water D, filter it to collect filter residue D, mix rinsing water D and filtrate C evenly to obtain mixed solution E; while stirring, first add a dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 50 L / min to adjust the pH of the solution to 9, and then add a dilute hydrochloric acid with a molar concentration of 1 mol / L to mixed solution E at a flow rate of 10 L / min to adjust the pH of the solution to 7, heat to evaporate the internal moisture, collect the solid to obtain sodium chloride product, and filter residue C enters the next process;

[0149] (3) While stirring, add a dilute hydrochloric acid with a molar concentration of 1 mol / L to the above-mentioned filter residue C at a flow rate of 50 L / min to adjust the pH of the solution to 5, and then add a dilute hydrochloric acid with a molar concentration of 1 mol / L to adjust the pH of the solution to 7 until filter residue C is completely dissolved; then add 1150.0 L of a dilute sulfuric acid with a molar concentration of 9 mol / L at a flow rate of 25 L / min to precipitate calcium ions, and the remaining operations are the same as in Example 1 to obtain calcium sulfate product;

[0150] (4) The same as in Example 1 to obtain hydrochloric acid solution product;

[0151] (5) The same as in Example 1 to obtain magnesium sulfate product.

[0152] Performance detection recovery rate: Calculate the recovery rates of iron ions, calcium ions, magnesium ions and chloride ions recovered from the non-fluoride-containing waste acid solutions in Examples 1 - 15, and record the sodium chloride yield. The specific calculation results are shown in Tables 1 and 3.

[0153] Purity detection of iron hydroxide: Detect the purity of iron hydroxide in Examples 1 - 12 according to HGT2574 - 2009 "Industrial Iron Oxide". The specific detection results are shown in Table 1.

[0154] Purity detection of sodium chloride: Detect the purity of sodium chloride in Examples 1 - 12 according to GB / T5462 - 2015 "Industrial Salt". The specific detection results are shown in Table 1.

[0155] Purity detection of calcium sulfate: Detect the purity of calcium sulfate in Examples 1 - 12 by direct titration method according to GB / T1892 - 2007. The specific detection results are shown in Table 1.

[0156] Magnesium sulfate detection: The purity of magnesium sulfate in Examples 1 - 12 was detected according to HG / T 2680 - 2017 "Industrial Magnesium Sulfate". The specific detection results are shown in Table 1.

[0157] Hydrochloric acid purity detection: The purity of hydrochloric acid in Examples 1 - 12 was detected according to GB / T 622 - 2006 "Chemical Reagent Hydrochloric Acid".

[0158] Table 1 Performance Detection Results of Different Recycled Products

[0159]

[0160] Table 2 Performance Detection Results of Different Recycled Products

[0161]

[0162]

[0163] The detection results in Table 1 and Table 2 show that through the recycling process of non - fluorine - containing waste acid solution, the recovery rate of the products recovered in this application is relatively high. The recovery rates of iron ions, calcium ions, magnesium ions and chloride ions are as high as 99.40%, 99.05%, 99.47% and 98.57% respectively, with a relatively high recovery and utilization rate. At the same time, the purity of the recovered products is relatively high. Among them, the purities of iron hydroxide, sodium chloride, calcium sulfate, magnesium sulfate and the concentration of high - purity hydrochloric acid solution are as high as 98.8%, 99.0%, 98.51%, 98.71% and 36.96% respectively. And the purity of the high - purity hydrochloric acid solution reaches the purity level of chemical reagents, improving the recovery quality of products such as iron hydroxide, sodium chloride, calcium sulfate, magnesium sulfate and high - purity hydrochloric acid solution in the waste acid solution, and making up for the increased production cost due to the treatment of non - fluorine - containing waste acid solution.

[0164] Combined with Examples 1 and 2 - 4, it can be seen that the recovery rates of calcium ions, magnesium ions, and chloride ions recovered from waste acid in Example 1 are 1.2 - 1%, 2.2 - 1%, and 2.6 - 1.3% higher than those in Examples 2 - 4 respectively; and the purities of the recovered iron hydroxide, calcium sulfate, and magnesium sulfate products and the concentration of the hydrochloric acid product from waste acid in Example 1 are 1.4%, 1.8 - 1.2%, 2.1 - 1.1%, and 2.5 - 1.9% higher than those in Examples 2 - 4 respectively. Additionally, the order of the comprehensive indexes of the recovery rates and purities / concentrations of the recovered iron hydroxide, sodium chloride, calcium sulfate, magnesium sulfate, and high - purity hydrochloric acid in Example 1 compared with Examples 2 - 4 is: Example 1 > Example 4 > Example 3 > Example 2. This shows that in step (1) of the present application for recovering iron hydroxide products, step (2) for recovering sodium chloride products, and step (3) for recovering calcium sulfate products, the recovered iron hydroxide solid, calcium hydroxide / magnesium hydroxide mixture solid, and calcium sulfate solid are rinsed, and the rinsing water is collected for recycling, which can improve the recovery utilization rates of calcium ions, magnesium ions, and chloride ions, and at the same time improve the purities of iron hydroxide, sodium chloride, calcium sulfate, and magnesium sulfate and the concentration of high - purity hydrochloric acid, thereby improving the recovery quality. The reason why the recovery utilization rates of calcium ions, magnesium ions, and chloride ions and the purities of iron hydroxide, sodium chloride, calcium sulfate, and magnesium sulfate and the concentration of high - purity hydrochloric acid in Examples 2 - 4 are lower than those in Example 1 may be related to the fact that a large amount of filtrate still remains in the iron hydroxide, calcium hydroxide, magnesium hydroxide, and calcium sulfate solids after filtration, and the filtrate contains a large amount of calcium, magnesium, and chloride ions.

[0165] Combined with Examples 1 and 5 - 6, it can be seen that the recovery rates and purities / concentrations of the recovered iron hydroxide, sodium chloride, calcium sulfate, magnesium sulfate, and high - purity hydrochloric acid in Example 5 are equal to those in Example 1, indicating that when the volume ratio of waste acid liquid to hydrogen peroxide in step (1) of the waste acid liquid recovery and treatment process is 1:15 - 30, the recovery rate of iron ions in the waste acid liquid is relatively high, the purity of the recovered iron hydroxide product is relatively high, and it has a relatively high recovery utilization rate. When the volume ratio of waste acid liquid to hydrogen peroxide is less than 1:15, that is, when the addition amount (concentration) of hydrogen peroxide in the waste acid reaches a certain amount and then the addition amount is increased, the recovery utilization rate and purity of the iron hydroxide product cannot be further improved.

[0166] In Example 6, the recovery rate of iron ions recovered from the waste acid solution is approximately 1.4% lower than that in Example 1, the purity of magnesium sulfate is approximately 1.3% lower, and the concentration of high-purity hydrochloric acid is approximately 0.8% higher. This indicates that when the volume ratio of the waste acid solution to hydrogen peroxide in process step (1) of the waste acid solution recovery treatment is greater than 1:30, that is, when the added volume of hydrogen peroxide in the waste acid does not reach a certain amount, not all of the divalent iron ions in the waste acid solution are converted into trivalent iron ions, resulting in a decrease in the recovery rate of the iron hydroxide product, a decrease in the purity of the magnesium sulfate product, and an increase in the concentration of high-purity hydrochloric acid. This is because the insufficient added amount (concentration) of hydrogen peroxide in the waste acid causes some divalent iron ions not to be oxidized by hydrogen peroxide to trivalent iron ions and then hydrolyze and precipitate, but to enter filtrate G. After adding sulfuric acid to filtrate G, the trivalent iron ions form iron sulfate and hydrochloric acid, and then enter the mixed solution I. After heating the mixed solution I, it enters the magnesium sulfate product, reducing the purity of the magnesium sulfate product and increasing the concentration of the high-purity hydrochloric acid product, and reducing the recovery rate of iron ions.

[0167] Combining Example 1 and Example 7, it can be seen that in Example 7, the recovery rate of iron ions recovered from the waste acid solution is approximately 1.3% lower than that in Example 1, the purity of magnesium sulfate is approximately 2.2% lower, and the concentration of high-purity hydrochloric acid is approximately 1% higher. This indicates that when adding sodium hydroxide to the waste acid at a high flow rate of 50 min / L until the pH value reaches 7, due to the large flow rate, the time for the pH value of the waste acid solution to reach 7 is short, resulting in incomplete hydrolysis and precipitation of all trivalent iron ions, and a small amount of trivalent iron ions entering filtrate G, reducing both the recovery rate and purity of iron ions. After adding sulfuric acid to filtrate G, the trivalent iron ions form iron sulfate and hydrochloric acid, and then enter the mixed solution I. After heating the mixed solution I, the iron sulfate enters the magnesium sulfate product, reducing the purity of the magnesium sulfate product and increasing the concentration of the high-purity hydrochloric acid product.

[0168] In Example 8, the yield of sodium chloride recovered from the waste acid solution is 25.24 kg higher than that in Example 1. This indicates that when adding sodium hydroxide to filtrate A at a high flow rate of 50 min / L until the pH value reaches 12, but due to the large flow rate, the actual pH value of filtrate A is greater than 12, and more hydrochloric acid is needed to neutralize filtrate C to a pH value of 7. Therefore, the yield of sodium chloride obtained after heating filtrate C is greater than that in Example 1, but the production cost is increased.

[0169] In Example 9, the concentration of the high-purity hydrochloric acid product recovered from the waste acid solution is approximately 1% higher than that in Example 1. This indicates that when adding hydrochloric acid to neutralize filtrate C at a high flow rate of 50 min / L until the pH value reaches 7, when the addition of hydrochloric acid is stopped when the pH value of filtrate C reaches 7, due to the large flow rate, a small amount of hydrochloric acid still enters filtrate C, resulting in an excess of hydrochloric acid in filtrate C and the actual pH value being less than 7. When evaporating filtrate C, the excess hydrochloric acid in filtrate C enters the high-purity hydrochloric acid product, increasing the distillation production cost.

[0170] In Example 10, the concentration of high-purity hydrochloric acid recovered from the waste acid solution is about 1% higher than that in Example 9. This indicates that when adding hydrochloric acid at a large flow rate of 50 min / L to dissolve the calcium / magnesium hydroxide mixture until the pH value reaches 7, after stopping the addition of hydrochloric acid when the pH value in filtrate C reaches 7, due to the large flow rate, a small amount of hydrochloric acid still enters filtrate C, resulting in an excessive amount of hydrochloric acid in filtrate C, making the actual pH value less than 7. When evaporating filtrate C, the excessive hydrochloric acid in filtrate C enters the high-purity hydrochloric acid product, increasing the distillation production cost.

[0171] The products recovered from the waste acid solution in Example 11 are basically the same as those in Example 1. This shows that in Example 11, when sodium hydroxide, hydrochloric acid, and sulfuric acid are added at a flow rate of 10 min / L to different specified pH values, it does not affect the recovery rate and purity / concentration of the products recovered from the waste acid solution. However, due to the extended time required to reach the specified pH value, the stirring time is increased, thereby increasing the production cost.

[0172] Combining Example 1 with Examples 7 - 11, it can be seen that in Example 1, the process of first adding sodium hydroxide or hydrochloric acid solution at a large flow rate of 50 L / min to adjust the solution pH close to the specified pH value and then adding it at a flow rate of 10 L / min until the solution pH reaches the specified pH has better comprehensive indicators of the recovery rate and purity / concentration of various products recovered from the waste acid solution than the process in Examples 7 - 10 of directly adding sodium hydroxide or hydrochloric acid solution at a large flow rate of 50 min / L to the waste acid solution until the pH value reaches the specified pH value. Moreover, the production cost of various products recovered from the waste acid solution in Example 1 is lower than that of the process of directly adding sodium hydroxide or hydrochloric acid solution at a flow rate of 10 L / min to the waste acid solution until the pH value reaches the specified pH value.

[0173] Combining Example 1 with Examples 12 - 13, it can be seen that the purity of the calcium sulfate product recovered from the waste acid solution in Example 12 is about 1.9% lower than that in Example 1. This may be because when adding dilute sulfuric acid solution at a flow rate of 30 L / min in Example 12, the local concentration of sulfuric acid solution in the solution is too high, resulting in too fast a precipitation rate of calcium sulfate, so that too many impurities are adsorbed and wrapped inside the calcium sulfate precipitate particles, making the purity of the calcium sulfate product lower than that in Example 1 where the dilute sulfuric acid solution is added at a flow rate of 24 - 26 L / min.

[0174] In Example 13, the recovery rates of calcium ions and magnesium ions recovered from the waste acid solution are approximately 1.5% lower and 1.5% lower than those in Example 1 respectively. The purity of the magnesium sulfate product is approximately 1.1% lower than that in Example 1, and the concentration of the high-purity hydrochloric acid product is approximately 2.8% lower than that in Example 1. This may be due to the fact that when the hydrochloric acid solution was added at a flow rate of 60 L / min in Example 13, the local temperature in the solution was too high, resulting in the solution splashing onto the inner wall of the equipment, so that the calcium hydroxide and magnesium hydroxide solids could not be completely dissolved by the hydrochloric acid. As a result, the recovery rates of calcium ions and magnesium ions, the purity of the magnesium sulfate product, and the concentration of the high-purity hydrochloric acid product are all lower than those in Example 1 where the dilute sulfuric acid solution was added at a flow rate of 50 L / min in terms of purity and concentration.

[0175] Combining Example 1 with Examples 14 - 15, it can be seen that in Example 14, when the addition amount of the dilute sulfuric acid solution was 1100 L, which is lower than the stoichiometric point of 1133.864 L, the volume of the dilute sulfuric acid solution was insufficient, resulting in the incomplete conversion of calcium chloride and magnesium chloride into calcium sulfate precipitate and magnesium sulfate during the reaction with sulfuric acid. As a result, the purity of the calcium sulfate and magnesium sulfate products and the concentration of the high-purity hydrochloric acid product are all lower than those in Example 1 with an addition amount of 1133.864 L at the stoichiometric point in terms of purity and concentration.

[0176] In Example 15, when the addition amount of the dilute sulfuric acid solution was 1150.0 L, which is higher than the stoichiometric point of 1133.864 L, the volume of the dilute sulfuric acid solution was excessive, resulting in the presence of sulfuric acid in the magnesium sulfate product obtained after heating. As a result, the purity of the magnesium sulfate product is lower than that in Example 1 with an addition amount of 1133.864 L at the stoichiometric point.

[0177] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A recovery and treatment process for non-fluoride-containing waste acid solution, wherein the non-fluoride-containing waste acid solution is an acidic solution containing calcium ions, magnesium ions, ferrous ions, ferric ions and chloride ions, and is characterized in that, It includes the following operation steps: (1) Add a sufficient amount of hydrogen peroxide solution to the waste acid solution to oxidize ferrous ions to ferric ions. Add sodium hydroxide solution while stirring, adjust the pH of the solution to neutral, let it stand, filter, and collect filtrate A and filter residue A; Filter residue A is ferric hydroxide, and filtrate A containing calcium ions, magnesium ions, chloride ions, and sodium ions enters the next process; (2) Add sodium hydroxide solution to filtrate A, adjust the pH of the solution to medium strong alkalinity to obtain hydrolysis solution B, let it stand, filter, and collect filtrate C and filter residue C; Filter residue C is a mixture of calcium hydroxide and magnesium hydroxide; Add dilute hydrochloric acid to filtrate C, adjust the pH of the solution to neutral, heat and evaporate the internal moisture, collect the solid to obtain sodium chloride product, and filter residue C enters the next process; (3) Add dilute hydrochloric acid solution to the above filter residue C, and adjust it to pH 7 while stirring; Add sulfuric acid with a molar concentration of 9 mol / L at the stoichiometric point to precipitate calcium ions, let it stand, filter, and collect filtrate G and filter residue G. Filter residue G is calcium sulfate; The acidic filtrate G containing magnesium ions, sulfate ions, and chloride ions enters the next process; (4) Under a stirring speed of 30 - 60 r / min, heat filtrate G at 60 - 80 °C until no hydrogen chloride gas is produced. Absorb hydrogen chloride gas with deionized water during the heating process to obtain a high-purity hydrochloric acid solution product, and the remaining mixed solution I containing magnesium ions and sulfate ions enters the next process; (5) Heat and evaporate the internal moisture of the above mixed solution I, collect the solid to obtain magnesium sulfate product; In step (1), first add sodium hydroxide solution at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 5; Then add sodium hydroxide solution at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7; In step (2), first add sodium hydroxide solution at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 11; Then add sodium hydroxide solution at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 12.5; In step (2), first add dilute hydrochloric acid at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 9; then add dilute hydrochloric acid at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7; In step (3), first add dilute hydrochloric acid at a flow rate of 40 - 60 L / min to adjust the pH of the solution to 5; Then add dilute hydrochloric acid at a flow rate of 8 - 12 L / min to adjust the pH of the solution to 7.

2. The recovery and treatment process for non-fluoride-containing waste acid solution according to claim 1, characterized in that, In step (1), the volume ratio of the hydrogen peroxide solution to the waste acid solution is 1:(15 - 30).

3. The recovery and treatment process for non-fluoride-containing waste acid solution according to claim 1, characterized in that, In step (1), rinse filter residue A with clean water. Stop rinsing when the conductivity of rinse water A reaches the same as that of the clean water used for rinsing. Collect rinse water A. After filter residue A is rinsed and purified with clean water, filter residue B is obtained. Collect filter residue B. Filter residue B is the purified ferric hydroxide product; Rinse water A enters the next process together with filtrate A.

4. The recovery and treatment process for non-fluoride-containing waste acid solution according to claim 1, characterized in that, In the step (2), before adding dilute hydrochloric acid to the filter residue C, the filter residue C is first rinsed, and the rinsing is stopped when the pH of the rinsing water B reaches 6-7. The rinsing water B is collected. The filter residue C is rinsed and purified with clear water to obtain a filter residue D, and the filter residue D is collected, which is a mixture of purified calcium hydroxide and magnesium hydroxide. After mixing the rinsing water B and the filtrate C, dilute hydrochloric acid is added for the remaining operations.

5. The recovery and treatment process for non-fluoride-containing waste acid solution according to claim 1, characterized in that, In the step (3), the filter residue G is rinsed, and the rinsing is stopped when the pH of the rinsing water C reaches 6-7. The filter residue G is rinsed and purified with clear water to obtain a filter residue H. The filter residue H and the rinsing water C are collected. The filter residue H is the purified calcium sulfate product, and the rinsing water C enters the next process together with the filtrate G.

Images