Resource utilization method of smelting waste acid

Abstract

The invention relates to the technical field of smelting pollution treatment, in particular to a resource utilization method of smelting waste acid. The resource utilization method of the smelting waste acid comprises the following steps: mixing the smelting waste acid with hydrogen sulfide at 10-30 DEG C to obtain a first treatment solution; mixing the first treating fluid with magnesium oxide to obtain a second treating fluid; and heating the second treatment liquid to 100 DEG C or above. According to the method, high-valued utilization of the sulfuric acid in the nonferrous smelting waste acid is achieved, meanwhile, efficient separation and resource utilization of arsenic, fluorine and chlorine impurity elements in the waste acid are achieved, no waste residues are generated in the whole process, no waste water or waste gas is discharged, and the method has the advantages of being short in process, easy to operate, low in cost and the like and has important significance on sustainable development of the nonferrous smelting industry.

Description

Technical Field

[0001] The invention relates to the technical field of non-ferrous smelting pollution control, and in particular to a method for resource utilization of smelting waste acid. Background Art

[0002] The raw materials for non-ferrous metal smelting are mostly sulfide ores. The sulfur dioxide flue gas produced during the roasting or smelting process of sulfide ores needs to be purified and removed before acid production. The purified output contains 5-10% acid and contains relatively high impurities such as fluorine, chlorine, and arsenic. This waste acid cannot be returned to the wet process system because it contains impurities such as fluorine, chlorine, and arsenic. Domestic and foreign waste acid disposal methods mostly use the "lime neutralization" method, all of which aim to meet the wastewater discharge standards, and produce a large amount of hazardous waste acid residue that needs to be waterproofed, anti-seepage, and anti-flying disposal, which occupies a large area and poses a high risk of environmental pollution. The sulfuric acid in the waste acid forms gypsum residue containing a large amount of heavy metals and calcium fluoride. Not only is the sulfuric acid resource not effectively utilized, but the gypsum residue needs to be disposed of or stored at a high cost. The neutralized liquid also needs to be processed through softening, multi-media filtration, ultrafiltration, reverse osmosis, electrodialysis and other processes. The overall process is long, the cost is high, and the labor input is large, which seriously affects the economic benefits of the enterprise. The existing technology uses lime milk to neutralize the waste acid in two stages. The first stage produces no heavy gypsum slag, and the second stage produces heavy gypsum slag. The liquid after the second stage of neutralization is softened with CO2 and then reused in the system. In this method, the fluorine in the waste acid enters the first stage of neutralization gypsum slag in the form of calcium fluoride, which is difficult to recycle; heavy metals such as arsenic enter the second stage of neutralization gypsum slag, which is also a hazardous waste slag, and chlorine still remains in the liquid after the second stage of neutralization. With the increasingly stringent national environmental protection standards, it is difficult to achieve stable wastewater discharge with the existing disposal methods, especially in areas where special emission limits are implemented, which seriously restricts the sustainable development of the non-ferrous smelting industry.

[0003] Therefore, it is necessary to strengthen the research on the process technology for resource utilization of waste acid from non-ferrous smelting, efficiently separate heavy metals and fluorine and chlorine impurities, and realize the resource utilization of sulfuric acid, arsenic, fluorine and chlorine in the waste acid, so as to achieve zero emission of the three wastes. This will not only effectively combine the economic benefits of the enterprise with the ecological and environmental benefits, but also have important significance for the sustainable development of the non-ferrous smelting industry.

[0004] Therefore, it is urgent to develop a resource utilization method for smelting waste acid. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a resource utilization method of smelting waste acid, which has the advantages of short process, easy operation and low cost.

[0006] To this end, the first aspect of the present invention provides a method for resource utilization of smelting waste acid, comprising the following steps:

[0007] Mixing the smelting waste acid with hydrogen sulfide at 10-30° C. to obtain a first treatment liquid;

[0008] mixing the first treatment liquid and magnesium oxide to obtain a second treatment liquid;

[0009] The second treatment liquid is heated to above 100°C.

[0010] The process of the present invention comprises: firstly treating the smelting waste acid with hydrogen sulfide to remove heavy metal elements such as arsenic, trace mercury, and trace zinc; then treating the liquid after arsenic removal (first treatment liquid) with magnesium oxide to produce a magnesium fluoride product and a second treatment liquid; evaporating and dechlorinating the second treatment liquid to volatilize the chlorine in the form of HCl and collect the hydrochloric acid product. The method of the present invention realizes the efficient separation and resource utilization of arsenic, fluorine, and chlorine impurity elements in the waste acid while making high-value use of sulfuric acid in the non-ferrous smelting waste acid. No waste residue is generated in the whole process, and no waste water or waste gas is discharged. It has the advantages of short process, easy operation, low cost, etc., and is of great significance to the sustainable development of the non-ferrous smelting industry.

[0011] In some embodiments of the present invention, the smelting waste acid and hydrogen sulfide are mixed for 3 to 6 hours at 10 to 30° C. The inventors have found that if the reaction temperature is too low or the reaction time is too short, the effect of removing arsenic, mercury and zinc is poor; if the reaction temperature is too high, energy consumption will increase.

[0012] In some embodiments of the present invention, the first treatment solution and magnesium oxide are mixed at 70 to 90° C. The temperature of 70 to 90° C. can improve the defluorination efficiency of magnesium oxide while controlling the cost.

[0013] In some embodiments of the present invention, the mixing time of the first treatment liquid and the magnesium oxide is 1 to 5 hours; in some preferred embodiments of the present invention, the mixing time of the smelting waste acid and hydrogen sulfide is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours.

[0014] In some embodiments of the present invention, the end point pH of the mixture of the first treatment solution and the magnesium oxide is 4-6.

[0015] In some embodiments of the present invention, the purity of the magnesium oxide is ≥ 90%. Thus, a better defluorination effect can be achieved on the basis of improving the defluorination efficiency.

[0016] In some embodiments of the present invention, the first treatment liquid is treated with magnesium oxide to obtain a second treatment liquid and magnesium fluoride; in the second treatment liquid, the fluorine content is ≤42.65 mg / L, and the purity of magnesium fluoride is ≥95.97%. The present invention uses magnesium oxide to treat the first treatment liquid and simultaneously produces a magnesium fluoride product, thereby increasing the output variety of the product and improving the economic benefits of the entire process; in addition, magnesium fluoride is widely used in many industrial fields (such as metallurgy, ceramics, electronics, etc.) and can be used as a raw material to further create value.

[0017] In some embodiments of the present invention, after obtaining the second treatment liquid and before heating the second treatment liquid, the second treatment liquid is evaporated and concentrated at a low temperature of 70 to 90°C.

[0018] In some embodiments of the present invention, the low-temperature evaporation concentration takes 1 to 5 hours.

[0019] In some embodiments of the present invention, the second treatment liquid is heated to above 100° C. for 1 to 5 hours.

[0020] In some embodiments of the present invention, the second treatment liquid is heated to above 100° C. to obtain a dechlorinated liquid. The high-temperature evaporation can volatilize the chlorine in the second treatment liquid in the form of HCl to obtain a hydrochloric acid product. After the dechlorination step is completed, the chlorine content in the dechlorinated liquid is ≤100 mg / L, and the mass fraction of HCl in the hydrochloric acid product is greater than 31%.

[0021] In some embodiments of the present invention, the second treated liquid is heated to above 100°C, and high-temperature evaporation and concentration are performed to obtain a dechlorinated liquid; the dechlorinated liquid is cooled; and the cooling temperature is 20 to 48°C. Thus, a magnesium sulfate heptahydrate product can be obtained. Magnesium sulfate heptahydrate is used in agriculture, medicine, printing and dyeing and other industries, realizing the resource utilization of magnesium, sulfur and other elements in waste acid.

[0022] In some embodiments of the present invention, the liquid obtained after solid-liquid separation is returned to the dechlorination step for evaporation and dechlorination, thereby further saving resources.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 A flow chart showing a method for resource utilization of smelting waste acid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0028] The proportion of sulfide minerals in non-ferrous metal smelting raw materials has gradually increased. As the grade of minerals decreases, the content of impurity elements such as arsenic, lead, and cadmium has also gradually increased. Enterprises discharge a large amount of acidic wastewater containing arsenic, lead, and cadmium in the purification process, which is called polluted acid. The arsenic concentration in polluted acid is usually 0.5-20g / L. Since the heavy metal ions such as arsenic, lead, mercury, and cadmium in the polluted acid seriously exceed the standard, it can be discharged or reused after purification. The existing technology usually uses lime neutralization method for treatment, which produces a large amount of gypsum hazardous waste storage.

[0029] To this end, the first aspect of the present invention provides a method for resource utilization of smelting waste acid, comprising the following steps:

[0030] Mixing the smelting waste acid with hydrogen sulfide at 10-30° C. to obtain a first treatment liquid;

[0031] mixing the first treatment liquid and magnesium oxide to obtain a second treatment liquid;

[0032] The second treatment liquid is heated to above 100°C.

[0033] The process of the present invention comprises: firstly treating the smelting waste acid with hydrogen sulfide to remove heavy metal elements such as arsenic, trace mercury, and trace zinc; then treating the liquid after arsenic removal (first treatment liquid) with magnesium oxide to produce a magnesium fluoride product and a second treatment liquid; evaporating and dechlorinating the second treatment liquid to volatilize the chlorine in the form of HCl and collect the hydrochloric acid product. The method of the present invention realizes the efficient separation and resource utilization of arsenic, fluorine, and chlorine impurity elements in the waste acid while making high-value use of sulfuric acid in the non-ferrous smelting waste acid. No waste residue is generated in the whole process, and no waste water or waste gas is discharged. It has the advantages of short process, easy operation, low cost, etc., and is of great significance to the sustainable development of the non-ferrous smelting industry.

[0034] In some embodiments of the present invention, the smelting waste acid is zinc smelting waste acid and / or copper smelting waste acid. The main components of zinc smelting waste acid are H2SO4 40-60g / L, As 3-2-10g / L, Zn 2+ 30-60mg / L, F - 2-10g / L, Cl - 1-10g / L. The main components of copper smelting waste acid are H2SO4 40-60g / L, As 3- 5-15g / L, Cu 2+ 2-10mg / L, F - 2-10g / L, Cl - 1-10g / L.

[0035] The present invention has no particular limitation on the source of the hydrogen sulfide. In some embodiments of the present invention, the hydrogen sulfide is in a gaseous state, and is preferably synthesized from sulfur and hydrogen.

[0036] In some embodiments of the present invention, the purity of hydrogen sulfide gas is ≥ 60%; in some preferred embodiments of the present invention, the purity of hydrogen sulfide gas is 62%. Thus, heavy metal impurities such as arsenic in smelting waste acid can be effectively removed.

[0037] In some embodiments of the present invention, the mixing of the smelting waste acid and hydrogen sulfide is performed by passing hydrogen sulfide gas into the smelting waste acid.

[0038] In some embodiments of the present invention, the molar ratio of hydrogen sulfide to arsenic is 1:(1.5-3). As an example, the molar ratio of hydrogen sulfide to arsenic can be 1:1.5, 1:2, 1:2.5 or 1:3.

[0039] In some embodiments of the present invention, at 10-30°C, the mixing time of the smelting waste acid and hydrogen sulfide is 3-6 hours; in some preferred embodiments of the present invention, the mixing temperature can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or 30°C; in some preferred embodiments of the present invention, the mixing time of the smelting waste acid and hydrogen sulfide is 3, 3.5, 4, 4.5, 5, 5.5 or 6 hours. The inventors have found that if the reaction temperature is too low or the reaction time is too short, the effect of removing arsenic, mercury and zinc is not good; if the reaction temperature is too high, the energy consumption will increase.

[0040] The reaction equation of hydrogen sulfide and impurities in smelting waste acid is as follows:

[0041] 2H3AsO3+3H2S=As2S3↓+6H2O

[0042] Hg 2+ +H2S=HgS↓+2H +

[0043] Zn2+ +H2S=ZnS↓+2H +

[0044] Cu 2+ +H2S=CuS↓+2H +

[0045] In some embodiments of the present invention, after impurities are removed by hydrogen sulfide, a first treatment liquid and arsenic sulfide slag and other heavy metal sulfides are obtained; the arsenic content in the first treatment liquid is ≤16 mg / L; the arsenic sulfide slag contains ≥40% arsenic. The smelting waste acid after hydrogen sulfide treatment can effectively remove heavy metal elements such as arsenic, trace mercury, and trace zinc, which can reduce the emission of these heavy metals in the environment and reduce the risk of pollution to the surrounding environment such as soil and water bodies, because these heavy metals are difficult to degrade in the natural environment and are easily enriched in organisms, endangering the ecosystem and human health. Arsenic sulfide slag can further recycle arsenic, realizing the transformation of arsenic in waste acid from a pollutant to a resource, improving resource utilization, and conforming to the concept of sustainable development.

[0046] In some embodiments of the present invention, the first treatment solution and magnesium oxide are mixed at 70-90° C.; in some preferred embodiments of the present invention, the mixing temperature is 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 or 90° C. The temperature of 70-90° C. can improve the defluorination efficiency of magnesium oxide while controlling the cost.

[0047] In some embodiments of the present invention, the mixing time of the first treatment liquid and the magnesium oxide is 1 to 5 hours; in some preferred embodiments of the present invention, the mixing time of the smelting waste acid and hydrogen sulfide is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours.

[0048] In some embodiments of the present invention, the end point pH of the mixture of the first treatment solution and the magnesium oxide is 4 to 6. As an example, the end point pH of the mixture of the first treatment solution and the magnesium oxide can be 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5 or 6.0.

[0049] In some embodiments of the present invention, after the first treatment solution and magnesium oxide are mixed for 1 to 5 hours, the pH of the system is 4.5 to 5.5.

[0050] In some embodiments of the present invention, the purity of magnesium oxide is ≥90%. In some preferred embodiments of the present invention, the purity of magnesium oxide is 92.34% or 94.65%. Thus, a better defluorination effect can be achieved on the basis of improving the defluorination efficiency.

[0051] In some embodiments of the present invention, the particle size of magnesium oxide is greater than 90% of -200 mesh; and the whiteness of magnesium oxide is ≥95%.

[0052] Magnesium oxide can react with fluorine in the first treatment solution, and the equation is as follows:

[0053] 2HF+MgO=MgF2↓+H2O

[0054] In some embodiments of the present invention, the first treatment liquid is treated with magnesium oxide to obtain a second treatment liquid and magnesium fluoride; in the second treatment liquid, the fluorine content is ≤42.65 mg / L, and the purity of magnesium fluoride is ≥95.97%. The present invention uses magnesium oxide to treat the first treatment liquid and simultaneously produces a magnesium fluoride product, thereby increasing the output variety of the product and improving the economic benefits of the entire process; in addition, magnesium fluoride is widely used in many industrial fields (such as metallurgy, ceramics, electronics, etc.) and can be used as a raw material to further create value.

[0055] In some embodiments of the present invention, after obtaining the second treatment liquid, before heating the second treatment liquid, the second treatment liquid is subjected to low-temperature evaporation and concentration at 70 to 90°C.

[0056] In some embodiments of the present invention, the low temperature evaporation concentration time is 1 to 5 hours; the magnesium content in the liquid after low temperature evaporation concentration is controlled to be 50 to 150 g / L. As an example, the low temperature evaporation concentration time can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours.

[0057] In some embodiments of the present invention, the second treatment liquid is heated to above 100°C for 1 to 5 hours. In some preferred embodiments of the present invention, the second treatment liquid is heated to 100 to 120°C. In other preferred embodiments of the present invention, the second treatment liquid is heated to 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119 or 120°C. The heating time is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours.

[0058] In some embodiments of the present invention, the second treatment liquid is heated to above 100°C, and high-temperature evaporation and concentration are performed to obtain a dechlorinated liquid; the dechlorinated liquid is cooled; and the cooling temperature is 20 to 48°C. High-temperature evaporation can volatilize the chlorine in the second treatment liquid in the form of HCl to obtain a hydrochloric acid product. After the dechlorination step is completed, the chlorine content in the dechlorinated liquid is ≤100 mg / L, and the mass fraction of HCl in the hydrochloric acid product is greater than 31%.

[0059] In some embodiments of the present invention, the method for resource utilization of smelting waste acid further comprises the following steps:

[0060] The cooled system is separated into solid and liquid to obtain a magnesium sulfate heptahydrate product; the solid-liquid separation is preferably centrifugal filtration. Thus, a magnesium sulfate heptahydrate product with a purity greater than 99.5% and an attached water content less than 20% can be obtained. Magnesium sulfate heptahydrate is used in agriculture, medicine, printing and dyeing and other industries, realizing the resource utilization of magnesium, sulfur and other elements in waste acid.

[0061] In some embodiments of the present invention, the liquid obtained after solid-liquid separation is returned to the dechlorination step for evaporation and dechlorination, thereby further saving resources.

[0062] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will appreciate that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Where the manufacturers of reagents or instruments are not indicated, they are all conventional products that can be obtained commercially.

[0063] Example 1

[0064] A method for resource utilization of smelting waste acid in this embodiment, the process flow chart is as follows Figure 1 As shown, the following steps are included:

[0065] (1) Arsenic sulfide precipitation: Take 200m3 of zinc smelting waste acid 3 The main component concentration is H2SO4 53.55g / L, As 3+ 2.52g / L, Zn 2+ 36mg / L, Hg + 25mg / L, F - 8.69g / L, Cl - 1.53g / L; hydrogen sulfide gas with a purity of 62% is introduced into the zinc smelting waste acid, and an excess coefficient of 1.5 times of arsenic is added, the reaction temperature is 15°C, and the reaction is carried out for 3 hours. After the reaction is completed, a sulfided liquid is obtained, wherein the sulfided liquid contains As 3+ 8.68mg / L, Zn 2+3.3mg / L, Hg + 1.56mg / L, the output arsenic sulfide slag contains 40.35% arsenic;

[0066] (2) Fluoride removal: Add industrial light magnesium oxide (HG / T2573-2006 standard) with a purity of 92%, a whiteness of 90%, and a particle size of 92%-200 mesh to the dearsenicized liquid, the reaction temperature is 85°C, the reaction is carried out for 3 hours, the end point pH is 4.6, the reaction is stopped, and the defluorinated liquid contains 42.65 mg / L fluorine, and the purity of magnesium fluoride is 95.97%;

[0067] (3) One-stage low-temperature evaporation concentration: The defluorinated liquid is subjected to one-stage low-temperature evaporation concentration at 85°C for 3 hours using steam. The concentrated liquid contains 123.54 g / L of magnesium. After the one-stage low-temperature evaporation concentration is completed, the steam becomes condensed water and is discharged through a pipeline;

[0068] (4) Two-stage high-temperature evaporation and concentration: After the first-stage low-temperature evaporation and concentration, the liquid is continuously subjected to a second-stage high-temperature evaporation and concentration with steam at 105° C. for 2 hours in a dechlorination device, and the evaporated tail gas is collected to produce a hydrochloric acid product with a mass fraction of HCl of 31.85%. The chlorine content of the liquid after evaporation and concentration is 56.34 mg / L;

[0069] (5) Cooling crystallization: The dechlorinated liquid is cooled to 32°C and filtered by a centrifuge to produce magnesium sulfate heptahydrate product with a purity of 99.68% and 18.56% of attached water and hydrochloric acid. The crystallized mother liquor is returned to the second high-temperature evaporation and concentration process.

[0070] Example 2

[0071] A method for resource utilization of smelting waste acid in this embodiment includes the following steps:

[0072] (1) Arsenic sulfide precipitation: Take 150m3 of waste acid from copper smelting 3 Its main components are H2SO4 46.54g / L, As 3+ 10.82g / L, Cu 2+ 65mg / L, Hg + 10mg / L, F - 2.71g / L, Cl - 3.86g / L. Hydrogen sulfide gas with a purity of 62% was introduced, and an excess coefficient of 2.0 times of arsenic was added. The reaction temperature was 28°C and the reaction was carried out for 5 hours to obtain a sulfided liquid, wherein the sulfided liquid contained As 3+ 15.54mg / L,Cu 2+ 2.78mg / L, Hg + 0.56mg / L, the output arsenic sulfide slag contains 43.58% arsenic;

[0073] (2) Fluoride removal: Add industrial light magnesium oxide (HG / T2573-2006 standard) with a purity of 93%, a whiteness of 92%, and a particle size of 95%-200 mesh to the dearsenicized liquid, the reaction temperature is 76°C, the reaction time is 2 hours, the end point pH is 5.0, the defluorinated liquid contains 36.12 mg / L fluorine, and the purity of magnesium fluoride is 96.64%;

[0074] (3) One-stage low-temperature evaporation concentration: The defluorinated liquid is subjected to one-stage low-temperature evaporation concentration at 80°C for 3 hours using steam. The concentrated liquid contains 145.06 g / L of magnesium. After the one-stage low-temperature evaporation concentration is completed, the steam becomes condensed water and is discharged through a pipeline;

[0075] (4) Two-stage high-temperature evaporation and concentration: After the first-stage low-temperature evaporation and concentration, the liquid is continuously subjected to a second-stage high-temperature evaporation and concentration with steam at 113° C. for 3 hours in a dechlorination device. The evaporated tail gas is collected to produce a hydrochloric acid product with a mass fraction of HCl of 32.12%. The chlorine content of the liquid after evaporation and concentration is 65.47 mg / L;

[0076] (5) Cooling crystallization: The dechlorinated liquid is cooled to 25°C and filtered by a centrifuge to produce magnesium sulfate heptahydrate product with a purity of 99.75% and an adhering water content of 17.36% and hydrochloric acid. The crystallized mother liquor is returned to the second high-temperature evaporation and concentration process.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 1 is the defluorination process, which specifically includes the following steps:

[0079] (1) Arsenic sulfide precipitation: Take 200m3 of zinc smelting waste acid 3 The main component concentration is H2SO4 53.55g / L, As 3+ 2.52g / L, Zn 2+ 36mg / L, Hg + 25mg / L, F - 8.69g / L, Cl - 1.53g / L; hydrogen sulfide gas with a purity of 62% is introduced into the zinc smelting waste acid, and an excess coefficient of 1.5 times of arsenic is added, the reaction temperature is 15°C, and the reaction is carried out for 3 hours. After the reaction is completed, a sulfided liquid is obtained, wherein the sulfided liquid contains As 3+ 8.68mg / L, Zn 2+ 3.3mg / L, Hg + 1.56mg / L, the output arsenic sulfide slag contains 40.35% arsenic;

[0080] (2) Fluoride removal: add industrial calcium oxide with a purity of 95%, a whiteness of 89%, and a particle size of 96%-200 mesh to the dearsenicized liquid, the reaction temperature is 82°C, the reaction is carried out for 3 hours, until the pH of the system reaches 5.5, the reaction is stopped, and the defluorinated liquid contains 18.37 mg / L fluoride and the purity of calcium fluoride is 32.42% (the remaining components are mainly calcium sulfate dihydrate);

[0081] (3) One-stage low-temperature evaporation and concentration: The defluorinated liquid is subjected to one-stage low-temperature evaporation and concentration at 85°C for 3 hours to produce a chlorine-free condensate water reuse system;

[0082] (4) Two-stage high-temperature evaporation and concentration: After the first low-temperature concentration, the liquid is further subjected to two-stage high-temperature evaporation and concentration at 105°C in a dechlorination device for 2 hours. The evaporated tail gas is collected to produce dilute hydrochloric acid with a mass fraction of 18.56% HCl. The chlorine content of the liquid after evaporation and concentration is 220.62 mg / L.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that the evaporation concentration process specifically comprises the following steps:

[0085] (1) Arsenic sulfide precipitation: Take 200m3 of zinc smelting waste acid 3 The main component concentration is H2SO4 53.55g / L, As 3+ 2.52g / L, Zn 2+ 36mg / L, Hg + 25mg / L, F - 8.69g / L, Cl - 1.53g / L; hydrogen sulfide gas with a purity of 62% is introduced into the zinc smelting waste acid, and an excess coefficient of 1.5 times of arsenic is added, the reaction temperature is 15°C, and the reaction is carried out for 3 hours. After the reaction is completed, a sulfided liquid is obtained, wherein the sulfided liquid contains As 3+ 8.68mg / L, Zn 2+ 3.3mg / L, Hg + 1.56mg / L, the output arsenic sulfide slag contains 40.35% arsenic;

[0086] (2) Fluoride removal: Add industrial light magnesium oxide (HG / T2573-2006 standard) with a purity of 92%, a whiteness of 90%, and a particle size of 92%-200 mesh to the dearsenicized liquid, the reaction temperature is 85°C, the reaction is carried out for 3 hours, the end point pH is 4.6, the reaction is stopped, and the defluorinated liquid contains 42.65 mg / L fluorine, and the purity of magnesium fluoride is 95.97%;

[0087] (3) Chlorine removal: The defluorinated liquid is heated to 106°C in a dechlorination device and evaporated for 5 hours. The evaporated tail gas is collected to produce a hydrochloric acid product with a HCl mass fraction of 30.85%. The chlorine content of the liquid after evaporation and concentration is 76.24 mg / L, which is reused as system makeup water.

[0088] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "some implementation schemes" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0089] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for resource utilization of smelting waste acid, characterized in that: The following steps are involved: Mixing the smelting waste acid with hydrogen sulfide at 10-30° C. to obtain a first treatment liquid; mixing the first treatment liquid and magnesium oxide to obtain a second treatment liquid; The second treatment liquid is heated to above 100°C.

2. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The time for mixing the smelting waste acid and hydrogen sulfide is 3 to 6 hours.

3. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The first treatment solution and magnesium oxide are mixed at 70-90°C.

4. The method for resource utilization of smelting waste acid according to claim 1 or 3, characterized in that: The mixing time of the first treatment liquid and the magnesium oxide is 1 to 5 hours.

5. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The end point pH of the mixture of the first treatment solution and the magnesium oxide is 4-6.

6. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The purity of the magnesium oxide is ≥90%.

7. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: Before heating the second treatment liquid, the second treatment liquid is evaporated and concentrated at a low temperature of 70 to 90°C.

8. The method for resource utilization of smelting waste acid according to claim 7, characterized in that: The time for the low-temperature evaporation concentration is 1 to 5 hours.

9. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The second treatment liquid is heated to 100-120° C. for 1-5 hours.

10. The method for resource utilization of smelting waste acid according to claim 1, characterized in that: The second treated liquid is heated to above 100°C and evaporated and concentrated at high temperature to obtain a dechlorinated liquid; the dechlorinated liquid is cooled; the cooling temperature is 20-48°C.

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