CN108675498B

CN108675498B - Method for resource utilization of stone coal acidic wastewater

Info

Publication number: CN108675498B
Application number: CN201810513729.7A
Authority: CN
Inventors: 董玉明; 李会强; 张笛; 裴丽丽; 张红玲; 徐红彬; 张懿
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2018-05-25
Filing date: 2018-05-25
Publication date: 2021-04-06
Anticipated expiration: 2038-05-25
Also published as: CN108675498A

Abstract

The invention provides a method for recycling stone coal acidic wastewater, which comprises the steps of heavy metal recovery, salt enrichment, magnesium-nitrogen double salt crystallization, jarosite precipitation, tail water recycling and the like. According to the invention, heavy metal ions are separated and recovered from the stone coal acidic wastewater, and magnesium-nitrogen double salt and jarosite are respectively obtained by a multi-step crystallization method, so that high-efficiency separation and recovery of different components in the wastewater are realized, the problem that a large amount of waste residues and valuable components generated by a traditional wastewater neutralization and deamination method cannot be recovered is solved, various products with high added values are obtained, the product purity is high, no heavy metal is entrained, the wastewater returns to a stone coal leaching process after treatment, and zero discharge of the wastewater is realized. The method has the advantages of low cost, simple operation, cleanness, environmental protection and the like.

Description

Method for resource utilization of stone coal acidic wastewater

Technical Field

The invention belongs to the technical field of wastewater treatment and resource utilization, and relates to a method for resource utilization of stone coal acidic wastewater.

Background

The stone coal is one of the main raw materials for extracting vanadium, and besides vanadium, the stone coal also contains various associated elements such as aluminum, potassium, iron, calcium, magnesium, molybdenum, nickel, cobalt, copper, titanium, chromium, uranium, selenium and the like. The roasting-water leaching/acid leaching method and the direct acid leaching method are common vanadium extraction processes of stone coal, so that a large amount of acidic wastewater is generated by the processes. The use of additives in the roasting process, stripping agents/desorbing agents in the vanadium enrichment process, precipitating agents in the vanadium precipitation process and the leaching of various associated elements in the leaching process lead to the residue of a large amount of Na in the wastewater⁺、NH₄ ⁺、K⁺、Mg²⁺、V⁵⁺And other heavy metal elements, so that heavy metal removal, desalination and ammonia nitrogen removal treatment are required to realize the recycling of the wastewater and the recovery of components.

At present, the common treatment method of the stone coal acidic wastewater is a lime neutralization-ammonia blowing-distillation desalination method, most of high-valence vanadium and chromium are reduced to be low-valence by reduction treatment, lime is added for neutralization, at the moment, the vanadium, the chromium, the iron, the aluminum and other heavy metals in the solution form sulfate and hydroxide precipitates, a large amount of calcium sulfate precipitates are generated by the sulfate and the lime, alkaline solution enters an ammonia blowing process, ammonia is absorbed by sulfuric acid to recover ammonium sulfate, finally salt-containing wastewater is distilled to obtain mixed salt, and steam condensate water is recycled. CN 1899977A discloses a method for treating and utilizing tail water from vanadium extraction and precipitation of stone coal, namely, procedures of lime neutralization and ammonia blowing are adopted. The conventional method has the advantages of good heavy metal ion removal effect, simple operation, less equipment and the like, but ferric hydroxide and aluminum hydroxide generated in the neutralization and precipitation process have better flocculation effect and adsorb a large amount of wastewater and metal ions, so the neutralization and precipitation amount is very large, and the precipitate belongs to dangerous waste and cannot be directly buried due to the entrainment of polluted heavy metal ions; the energy consumption of the ammonia blowing and distillation desalting processes is high, and secondary atmospheric pollution is easily caused in the ammonia blowing process; in the whole process, only ammonium sulfate can be recovered in the deamination process, evaporation condensate water can be recovered in the distillation desalination process, and other parts of heavy metal, alkali metal and alkaline earth metal cannot be separated and recovered.

Because the energy consumption is higher in the single distillation desalination process, scaling is easy, the salt-containing wastewater is treated by adopting a combination method, CN 101759313A discloses a resource treatment method for high-salinity heavy metal-rich wastewater in vanadium extraction from stone coal, lime is added into the stone coal wastewater to neutralize and adjust alkali, soda is added to reduce the hardness of water, a flocculating agent is added to reduce the turbidity of the water, electrodialysis desalination treatment is carried out to obtain fresh water and concentrated water, the fresh water is reused in the vanadium extraction process from stone coal, and the concentrated water is evaporated by adopting a four-effect low-temperature plate evaporator to obtain condensed water and industrial salt. CN 102642963A discloses a comprehensive treatment method for salt-containing wastewater from vanadium extraction from stone coal, which also adopts lime neutralization, soda ash hardness removal and flocculation precipitation for pretreatment, and then adopts reversed electrodialysis, reduced pressure membrane distillation and crystallization treatment in turn. Compared with a single distillation method, the process has lower energy consumption, but the membrane treatment such as electrodialysis still has the problems of higher requirement on water quality, easy membrane pollution, high cost of matched equipment and the like.

After heavy metal ions are removed from the stone coal wastewater, the cost of deamination and desalination is high by adopting the method, so that the chemical precipitation method, the crystallization method and the like are usually adopted to simplify the process and reduce the cost. Plum inspection et al (struvite precipitation method for treating low-concentration ammonia nitrogen wastewater from vanadium extraction from stone coal. industrial water treatment, 2010,30(9):35-38.) propose a method for removing ammonia nitrogen by generating struvite precipitate, adjust the pH value of wastewater, use magnesium chloride and disodium hydrogen phosphate as precipitating agents, control reaction conditions, generate struvite precipitate to reduce the ammonia nitrogen content in wastewater, meet the relevant national discharge standards, and the struvite precipitate can also be used as a compound fertilizer. CN 101343695A discloses a method for reducing the content of potassium and sodium in vanadium extraction leaching circulating liquid, which comprises the steps of firstly adjusting the solution to be acidic, heating and adding potassium and sodium removing agents containing iron ions, and controlling the pH value to carry out precipitation reaction. The chemical precipitation method and the crystallization method have low cost and less equipment investment, but only remove one kind of components in the wastewater, do not consider the integral composition of the wastewater, and do not effectively recycle valuable components.

In conclusion, the treatment of the stone coal acidic wastewater starts from integral composition, and various components in the wastewater are removed step by adopting a reasonable method, so that the cost of wastewater treatment can be reduced, and the valuable components can be recycled.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for recycling stone coal acidic wastewater. According to the invention, heavy metal ions are separated and recovered from the stone coal acidic wastewater, and then chemical components such as alkaline earth metal, ammonia nitrogen, alkali metal and the like are separated and recovered by adopting a multi-step crystallization method, so that various products with high added values are obtained, and the high-efficiency recycling of resources in the wastewater is realized while the wastewater is effectively treated; meanwhile, the process method has the advantages of low cost, simplicity in operation, cleanness, environmental friendliness and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for resource utilization of stone coal acidic wastewater, which comprises the following steps:

(1) recovering heavy metal ions in the stone coal acidic wastewater to obtain a heavy metal concentrate and a solution;

(2) enriching the solution obtained in the step (1), adding ammonium salt and/or magnesium salt, and crystallizing to obtain magnesium-nitrogen double salt and solution;

(3) and (3) adding the solution obtained in the step (2) into an iron-containing substance, carrying out precipitation reaction to obtain jarosite precipitate and a solution, and returning the obtained solution to the stone coal leaching process.

The invention mainly adopts a chemical method to realize resource utilization of the stone coal acidic wastewater, firstly separates and recovers heavy metal ions, and then realizes Mg by adding a reagent to form crystals²⁺、NH₄ ⁺、Na⁺And K⁺The separation and recovery of chemical components avoid the problems that a large amount of waste residues and valuable components generated by the traditional wastewater neutralization deamination method cannot be recovered, and the method has the advantages of low cost, simplicity in operation, cleanness, environmental friendliness and the like, and the waste water returns to the stone coal leaching process after being treated, so that zero discharge of the waste water is realized.

In the present invention, stone coalThe leaching process does not belong to the process step in the stone coal acidic wastewater treatment method, but belongs to the process of generating the wastewater, namely the step in the stone coal vanadium extraction process. Because only Mg is left after the wastewater treatment in the invention²⁺Higher concentration of other three ions NH₄ ⁺、Na⁺And K⁺The concentration of the vanadium is low, the evaporation amount in the wastewater treatment process is relatively small, the heavy metal enrichment degree is low, the solubility of magnesium sulfate is very high, and the vanadium extraction process of the stone coal cannot be influenced, so that the treated solution is preferably used as vanadium extraction process water to return to the leaching process to realize tail water recycling.

The following technical solutions are preferred but not limited to the technical solutions provided by the present invention, and the technical objects and advantages of the present invention can be better achieved and realized by the following technical solutions.

As the preferable technical scheme of the invention, the stone coal acidic wastewater in the step (1) is the wastewater of the process for extracting vanadium by a stone coal sulfuric acid method.

Preferably, the stone coal acid wastewater in the step (1) does not contain Cl^－And F^－。

In the invention, the stone coal acidic wastewater is wastewater generated after vanadium extraction from stone coal, and the stone coal does not contain Cl^－And F^－As long as no Cl is added in the process of acid leaching vanadium extraction^－And F^－Does not generate Cl^－And F^－The waste water and the prior clean vanadium extraction process also avoid Cl as much as possible^－And F^－The invention is used for treating the wastewater generated by the current clean production process.

Preferably, the pH of the stone coal acidic wastewater in the step (1) is less than 7, such as 6, 5, 4, 3, 2, 1, 0, -1 or-2, but not limited to the recited values, and other values not recited in the range of the values are also applicable, preferably 0 to 6.

Preferably, the heavy metal ion recovery in step (1) adopts an adsorption method or a precipitation method, preferably an adsorption method.

Preferably, the adsorbent used in the adsorption method is a chelating resin and/or a biological adsorbent.

Preferably, the functional group of the chelating resin includes any one of a nitrogen-containing functional group, a phosphorus-containing functional group, an oxygen-containing functional group, or a sulfur-containing functional group, or a combination of at least two thereof, as typical but non-limiting examples of the combination are: the functional group containing nitrogen and the functional group containing phosphorus are preferably a combination of the functional group containing nitrogen and the functional group containing sulfur, a combination of the functional group containing nitrogen, the functional group containing phosphorus and the functional group containing oxygen, a combination of the functional group containing phosphorus, the functional group containing oxygen and the functional group containing sulfur, and a combination of the functional group containing nitrogen, the functional group containing oxygen and the functional group containing sulfur.

Preferably, the biological adsorbent comprises any one of or a combination of at least two of natural organic adsorbents and modifications thereof, microorganisms and modifications thereof, or agricultural, forestry, animal husbandry and fishery waste and modifications thereof, and typical but non-limiting examples of the combination are: the combination of natural organic adsorbent and microorganism, the combination of natural organic adsorbent and modified substance thereof, the combination of microorganism and waste of agriculture, forestry, animal husbandry and fishery, the combination of natural organic adsorbent, microorganism and waste of agriculture, forestry, animal husbandry and fishery, and the like.

According to the invention, the adsorption method is preferentially adopted for recovering heavy metal elements, the used adsorbent can selectively recover heavy metals in the stone coal acidic wastewater, and alkali metals, alkaline earth metals and ammonia nitrogen can not be adsorbed, so that valuable single salt or double salt products of the alkali metals, the alkaline earth metals and the ammonia nitrogen can be conveniently purified and recovered by a crystallization method in the subsequent process, the problems that the process slag amount is large, a large amount of salt, ammonia nitrogen and unrecovered heavy metals are carried in mixed precipitates and the high-efficiency separation and recovery of valuable components in the wastewater can not be realized by the traditional neutralization and precipitation method are avoided.

Preferably, the precipitating agent used in the precipitation method is a sulfide.

Preferably, the sulphide comprises any one of sodium sulphide, potassium sulphide, ammonium sulphide, sodium hydrosulphide, potassium hydrosulphide or ammonium hydrosulphide, or a combination of at least two of these, typical but non-limiting examples being: combinations of sodium sulfide and potassium sulfide, sodium sulfide and sodium hydrosulfide, potassium sulfide and ammonium hydrosulfide, sodium sulfide, potassium sulfide and ammonium sulfide, sodium sulfide, potassium sulfide, sodium hydrosulfide and potassium hydrosulfide, and the like.

Preferably, the heavy metal concentrate of step (1) comprises a combination of at least two of vanadium, chromium, iron, cobalt, nickel, copper, zinc, or cadmium, typical but non-limiting examples of which are: combinations of vanadium and chromium, combinations of copper and zinc, combinations of iron, cobalt and nickel, combinations of vanadium, chromium, iron and cobalt, combinations of cobalt, nickel, copper, zinc and cadmium, and the like.

Preferably, the concentrate of step (1) further comprises aluminum and arsenic.

In the invention, the heavy metal concentrate produced by the adsorption method or the precipitation method is separated and recovered according to the prior art, and the content of the residual heavy metal in the residual solution meets the national relevant sewage discharge standard. As arsenic is a common harmful element in the stone coal wastewater, the arsenic can be removed by an adsorption method; the aluminum ions have a strong flocculation property and are adsorbed and removed in the treatment process of the adsorption method or the precipitation method, so that the obtained enriched material also comprises aluminum and arsenic.

As a preferable technical scheme of the invention, the enrichment method in the step (2) comprises any one of circulating leaching and evaporative concentration after returning to the stone coal leaching process or circulating leaching and evaporative concentration after returning to the stone coal leaching process, and preferably the evaporative concentration after returning to the stone coal leaching process.

In the invention, the stone coal leaching process does not belong to the process step in the stone coal acidic wastewater treatment method, but belongs to the process of generating the wastewater, namely the step in the stone coal vanadium extraction process.

Preferably, the evaporation concentration is performed under reduced pressure, and the degree of vacuum of the reduced pressure evaporation is 10 to 90kPa, for example, 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, or 90kPa, but the degree is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature of the evaporation concentration treatment is 60 to 100 ℃, for example, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃ or 100 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the steam obtained by the evaporation concentration treatment is condensed and then used in the stone coal vanadium extraction process.

As a preferable technical scheme of the invention, the high-concentration salt-containing solution obtained after the solution in the step (2) is enriched comprises Mg²⁺、Na⁺、K⁺And NH₄ ⁺。

Preferably, Mg in the high concentration salt-containing solution²⁺The concentration is 10 to 45g/L, for example, 10g/L, 15g/L, 20g/L, 25g/L, 30g/L, 35g/L, 40g/L or 45g/L, etc., but is not limited to the values listed, and other values not listed in the numerical range are also applicable, preferably 20 to 30 g/L.

Preferably, the high concentration salt-containing solution contains Na⁺The concentration is 135g/L or less, for example 135g/L, 120g/L, 100g/L, 90g/L, 80g/L, 70g/L, 60g/L, 50g/L, 40g/L or 30g/L, etc., but is not limited to the recited values, and other values not recited within the range of values are also applicable, preferably 90g/L or less.

Preferably, K is in the high concentration salt-containing solution⁺The concentration is 80g/L or less, for example 80g/L, 70g/L, 60g/L, 50g/L, 40g/L, 30g/L, 20g/L or 10g/L, etc., but is not limited to the recited values, and other values not recited within the range are also applicable, preferably 55g/L or less.

Preferably, the high concentration salt-containing solution contains NH₄ ⁺The concentration is 70g/L or less, for example 70g/L, 60g/L, 50g/L, 40g/L, 30g/L, 20g/L, 10g/L or 5g/L, etc., but is not limited to the recited values, and other values not recited within the range are also applicable, preferably 50g/L or less.

In the invention, the acid wastewater after heavy metal recovery is returned to the stone coal leaching process for enriching salt, and Na in the cyclic leaching process is controlled⁺、K⁺、Mg²⁺And NH₄ ⁺The concentration of the vanadium is higher, so that the problem that the leaching rate of the vanadium is reduced due to the influence of the diffusion leaching of the vanadium and the entrainment loss of the formed vanadium caused by the generation of sulfate precipitates caused by overhigh ion concentration is avoided.

In the invention, the circulation leaching process is adopted to enrich Na⁺、K⁺、Mg²⁺And NH₄ ⁺Compared with a single evaporation concentration method, the ion evaporation method can reduce the evaporation amount of water and reduce energy consumption; the method can also avoid the phenomenon that the heavy metal content in the solution is too high due to direct evaporation and enrichment and enters the byproducts, and the concentrated solution is subjected to the step of selectively recovering the heavy metal each time by adopting a circulating leaching method, so that the subsequent byproducts do not contain the heavy metal. However, the cyclic leaching method may not enrich ions in the solution to a sufficient concentration, and may be assisted with an evaporation concentration method to enrich ions to a higher concentration, so that the method of first cyclic leaching and then evaporation concentration is preferentially adopted, the former can reduce the evaporation amount of water, and the latter can enrich ions to a higher concentration, thereby improving the crystallization efficiency.

As a preferred embodiment of the present invention, the ammonium salt in step (2) includes any one or a combination of at least two of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium bisulfate, ammonium carbonate or ammonium bicarbonate, and the combination is exemplified by, but not limited to: a combination of ammonium chloride and ammonium sulfate, a combination of ammonium sulfate and ammonium bisulfate, a combination of ammonium bisulfate and ammonium bicarbonate, a combination of ammonium chloride, ammonium sulfate and ammonium nitrate, a combination of ammonium sulfate, ammonium bisulfate, ammonium carbonate and ammonium bicarbonate, and the like, preferably any one or a combination of at least two of ammonium sulfate, ammonium bisulfate, ammonium carbonate or ammonium bicarbonate, and more preferably ammonium sulfate and/or ammonium bisulfate.

In the present invention, the ammonium salt is added to replenish NH in the solution₄ ⁺Therefore contains NH₄ ⁺Other substances, such as ammonia, may be used as well.

Preferably, the magnesium salt in step (2) comprises any one of magnesium chloride, magnesium sulfate, magnesium phosphate, magnesium hydrogen sulfate, magnesium nitrate, magnesium carbonate, magnesium hydrogen carbonate or basic magnesium carbonate or a combination of at least two of them, and the combination is exemplified by, typically but not limited to: a combination of magnesium chloride and magnesium sulfate, a combination of magnesium sulfate and magnesium bisulfate, a combination of magnesium carbonate, magnesium bicarbonate and basic magnesium carbonate, a combination of magnesium sulfate, magnesium bisulfate, magnesium carbonate and magnesium bicarbonate, and the like, preferably any one or a combination of at least two of magnesium sulfate, magnesium bisulfate, magnesium carbonate and magnesium bicarbonate, and more preferably magnesium sulfate and/or magnesium bisulfate.

Preferably, the ammonium salt and/or the magnesium salt in the step (2) is added in an amount of MgSO (MgSO) for generating magnesium-nitrogen double salt₄·(NH₄)₂SO₄·6H₂O is preferably 0 to 2.5 times, for example, 0, 0.2, 0.5, 0.6, 0.8, 1, 1.2, 1.5, 2 or 2.5 times the theoretical amount of O, but not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, preferably 0.2 to 1.2 times.

In the present invention, when one of ammonium salt or magnesium salt is added, NH is added from the solution₄ ⁺And Mg²⁺If NH is present₄ ⁺And Mg²⁺If the molar ratio is greater than 2, magnesium salt should be added, if NH₄ ⁺And Mg²⁺If the molar ratio is less than 2, ammonium salt should be added. In addition, it is also possible to add ammonium salts and magnesium salts simultaneously, in which case, in combination with the factors of the amount added and the crystallization temperature, the crystallization effect of the ions with a smaller relative content is better than when one salt is added alone, and the other ions are removed by subsequent steps or recycling treatment, utilizing the homoionic effect.

In a preferred embodiment of the present invention, the temperature of the crystallization in the step (2) is 0 to 70 ℃, for example, 0 ℃, 10 ℃,20 ℃,30 ℃, 40 ℃, 50 ℃, 60 ℃ or 70 ℃, but not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are also applicable, preferably 10 to 60 ℃, and more preferably 20 to 40 ℃.

Preferably, the magnesium-nitrogen double salt in the step (2) is used as a magnesium-nitrogen compound fertilizer.

Preferably, the magnesium nitrogen double salt in the step (2) is used for agricultural production and/or forestry production.

The invention adopts the method of crystallization to generate magnesium-nitrogen double salt to Mg²⁺And NH₄ ⁺Recovering Na from the system⁺、NH₄ ⁺、K⁺、Mg²⁺And SO₄ ^2-Investigation of difference of crystallization regions and combination of low-temperature solubility ratio Na of magnesium-nitrogen double salt⁺、NH₄ ⁺And K⁺The sulfate has low solubility, so that the magnesium-nitrogen double salt with high purity can be obtained by cooling and crystallizing in a proper temperature range, the magnesium content in the double salt is 6.7 wt%, the ammonium content is 10 wt%, and the magnesium-nitrogen compound slow-release fertilizer is suitable for being used as a magnesium-nitrogen compound slow-release fertilizer in agricultural and forestry production.

As a preferred embodiment of the present invention, the iron-containing substance in step (3) includes any one or a combination of at least two of iron sulfate, iron chloride, iron nitrate, iron phosphate, iron hydroxide, iron oxide, iron-rich minerals, or iron-rich tailings, and the combination is typically, but not limited to, as follows: a combination of iron sulfate and iron hydroxide, a combination of iron hydroxide and iron oxide, a combination of an iron-rich mineral and an iron-rich tailings, a combination of iron sulfate, iron hydroxide and iron oxide, and the like, preferably any one or a combination of at least two of iron sulfate, iron hydroxide and iron oxide, and more preferably iron sulfate.

In the invention, the iron-containing substance is preferably ferric sulfate, ferric hydroxide or ferric oxide, namely, other anion components are not introduced into the system under the acidic condition, so that only sulfate precipitation can be obtained in the subsequent crystallization process.

Preferably, the iron-containing substance is added in an amount of 0.1 to 3 times, for example, 0.1 times, 0.3 times, 0.5 times, 0.8 times, 1 times, 1.2 times, 1.5 times, 2 times, 2.5 times or 3 times, the theoretical amount required for producing jarosite, but is not limited to the recited values, and other values not recited in the numerical range are also applicable, preferably 0.5 to 1.5 times, and more preferably 0.8 to 1 time.

Preferably, the composition of the jarosite is MFe₃(SO₄)₂(OH)₆Wherein M is Na⁺、NH₄ ⁺Or K⁺Any one or a combination of at least two of the following, typical but non-limiting examples being: na (Na)⁺And NH₄ ⁺Combination of (A) and (B), Na⁺And K⁺Combination of (A) and (B), Na⁺、NH₄ ⁺And K⁺Combinations of (a), (b), and the like.

In the present invention, alum refers to a double salt composed of two or more kinds of metal sulfates, and the addition of an iron-containing substance to generate an jarosite precipitate is because it is more likely to crystallize out of solution than the corresponding single salt, and can also form larger grains, which is advantageous for solid-liquid separation.

In the present invention, the theoretical amount of iron-containing material required to form jarosite is based on Na in solution⁺、NH₄ ⁺And K⁺Is calculated from the total amount of (c).

In a preferred embodiment of the present invention, the pH of the precipitation reaction in step (3) is-2 to 4, for example, -2, -1.5, -1, -0.5, 0, 0.5, 1, 1.5, 2, 3 or 4, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, preferably-1 to 3, and more preferably 0 to 1.3.

Preferably, the pH is adjusted with an acidic or basic substance.

In the present invention, the process of producing jarosite produces an acid having the formula 3Fe³⁺+2SO₄ ^2-+M⁺+6H₂O＝MFe₃(SO₄)₂(OH)₆+6H⁺Therefore, it is necessary to continuously adjust the pH of the solution so that the precipitation reaction is always performed within this pH range.

Preferably, the acidic substance comprises any one of hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, or a combination of at least two of these, typical but non-limiting examples being: a combination of hydrochloric acid and nitric acid, a combination of phosphoric acid and sulfuric acid, a combination of hydrochloric acid, phosphoric acid and sulfuric acid, and the like, with sulfuric acid being preferred.

Preferably, the basic substance comprises any one of sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate or a combination of at least two of them, typical but non-limiting examples being: a combination of sodium hydroxide and potassium hydroxide, a combination of sodium carbonate and potassium carbonate, a combination of sodium hydroxide, sodium carbonate and sodium bicarbonate, a combination of sodium hydroxide, potassium hydroxide and aqueous ammonia, and the like, and preferably any one of or a combination of at least two of sodium hydroxide, potassium hydroxide or aqueous ammonia.

In the invention, the pH value is preferably adjusted by sulfuric acid, sodium hydroxide, potassium hydroxide or ammonia water, and other components are not introduced into the system, so that only sulfate precipitate can be obtained in the subsequent crystallization process.

Preferably, the temperature of the precipitation reaction in step (3) is 30 to 200 ℃, for example, 30 ℃, 50 ℃, 60 ℃, 80 ℃, 100 ℃, 120 ℃, 150 ℃, 180 ℃ or 200 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable, preferably 60 to 150 ℃, and more preferably 101 to 150 ℃.

Preferably, the precipitation reaction time in step (3) is 0.2 to 8 hours, such as 0.2 hour, 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable, preferably 0.5 to 6 hours, and more preferably 1 to 4 hours.

The method for separating and recovering Na by adopting the crystallized jarosite is adopted in the invention⁺、K⁺And NH₄ ⁺By controlling the adding amount of iron-containing substances, the pH value of the solution, the precipitation temperature and other conditions, the jarosite precipitate with higher purity can be obtained, and Fe in the solution³⁺Basically has no residue, the precipitation rate of the jarosite is higher, and the residual Na⁺、K⁺And NH₄ ⁺The concentration is low, and the requirement of returning to the process of extracting vanadium from stone coal acid is met.

The invention adopts harsher reaction conditions to crystallize the jarosite, not only from the viewpoint of precipitating the jarosite, but also in order to avoid the entrainment loss of vanadium in the crystallization process, because the vanadium is cation under the pH condition, VO₂ ⁺Even at higher temperature, the iron vanadate precipitate can not be generated with iron, so the high-temperature precipitated jarosite avoids the entrainment of vanadium, the vanadium can enter into multi-metal concentrates, and the residual VO₂ ⁺And returning to the stone coal acid leaching process, and recovering vanadium in the wastewater, thereby realizing zero discharge of the wastewater and efficient utilization of resources.

Preferably, the jarosite precipitate of step (3) is used for recovering valuable components or for landfill disposal.

Preferably, the jarosite precipitate is recovered to obtain an ammonium sulfate solution, iron oxide and an alkali metal sulfate solution.

In the invention, the generated jarosite precipitate comprises jarosite, ammonioiarosite and jarosite, and the method for recovering the valuable components comprises the following steps: and recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

The ammonium sulfate solution can be used for a vanadium extraction process or for preparing the magnesium-nitrogen compound fertilizer in the step (2), the iron oxide product can be used for removing alkali metals in the step (3), and the alkali metal sulfate solution can be used for separating and recovering potassium and sodium according to the existing process.

According to the invention, through stone coal leaching, cyclic leaching and evaporation concentration are carried out, obtained jarosite is enriched to be a mixture, ammonium sulfate, ferric oxide and a high-concentration potassium-sodium mixed salt solution are recovered through a roasting-washing method, wherein the ammonium sulfate and the ferric oxide can be returned to a stone coal vanadium extraction process, and because the roasting method is high in deamination rate, the potassium-sodium mixed salt solution basically does not contain ammonium radicals, and potassium sulfate and sodium sulfate with high purity can be directly separated through methods such as crystallization and the like. In the traditional lime neutralization-deamination-distillation desalting method, because the deamination rate is not particularly high, ammonium radicals still remain in a potassium-sodium mixed salt solution after deamination, and a large amount of ammonium sulfate still remains in mixed salt obtained by final distillation desalting.

In the invention, the jarosite precipitate does not contain heavy metal, and can be directly buried after being washed and deacidified.

In the invention, insufficient iron-containing compound is added into the precipitated jarosite, and the more rigorous reaction conditions are adopted, so that the Fe residual in the solution is ensured to be less through theoretical analysis and experimental verification³⁺The jarosite has high crystallization purity and does not carry waste water components such as heavy metals, so valuable components can be selectively recycled or buried.

At present, the technology for removing the alkali metal-containing industrial wastewater in other industries also adopts the jarosite method, and in order to complete the reaction, a large amount of iron-containing compounds are added in the technology or the reaction is carried out at a lower temperature (less than or equal to 100 ℃), so that a large amount of Fe is contained in the wastewater³⁺Residual, the solution must be adjusted to a higher pH to remove Fe³⁺So that a large amount of precipitates are generated, which wastes resources, and the precipitates can not meet the requirements of common wastes and can not be directly buried because most of the precipitates are iron hydroxides which have good flocculation and carry wastewater and various components in the wastewater.

In the invention, tail water is obtained after wastewater treatment, and Fe in tail water solution³⁺、Na⁺、K⁺And NH₄ ⁺The residual quantity of the waste water meets the requirement of returning to the acid leaching process, and the steam condensate water generated in the whole waste water treatment process is used in the process of extracting vanadium from stone coal, thereby realizing zero discharge of waste water and high-efficiency utilization of resources.

As a preferred technical scheme of the invention, the method comprises the following steps:

(1) recovering heavy metal ions in the stone coal acidic wastewater by adopting an adsorption method or a precipitation method to obtain a heavy metal concentrate and a solution;

(2) returning the solution obtained in the step (1) to a stone coal leaching process for cyclic leaching, evaporating, concentrating and enriching, wherein the vacuum degree of evaporation concentration treatment is 10-90 kPa, the temperature is 60-100 ℃, then adding ammonium salt and/or magnesium salt, and crystallizing at 0-70 ℃ to obtain magnesium-nitrogen double salt and solution;

(3) adding an iron-containing substance into the solution obtained in the step (2), adjusting the pH value of the solution to-2-4, carrying out precipitation reaction at the temperature of 30-200 ℃ for 0.2-8 h to obtain jarosite precipitate and a solution, and returning the obtained solution to the stone coal leaching process.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method is combined with the ion composition of a stone coal wastewater system, and adopts a multi-step crystallization method to respectively obtain magnesium-nitrogen double salt and jarosite, so that the high-efficiency separation of different components in the wastewater is realized, products with high added values are obtained by recovery, the purity of byproducts is high, and no heavy metal is entrained;

(2) the invention realizes the selective recovery of heavy metal ions and avoids the generation of a large amount of dangerous waste residues which are difficult to be recycled;

(3) the tail water solution obtained by the invention is circularly treated, zero discharge of waste water and efficient recovery of resources are realized, and the method has the advantages of low cost, simple operation, cleanness, environmental protection and the like.

Drawings

Fig. 1 is a process flow chart of a stone coal acidic wastewater resource utilization method provided in the section of the embodiment of the invention.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The specific embodiment of the invention provides a method for recycling stone coal acidic wastewater, and the process flow diagram of the method is shown in figure 1, and the method comprises the following steps:

The following are typical but non-limiting examples of the invention:

example 1:

the embodiment provides a method for resource utilization of stone coal acidic wastewater, which comprises the following main components in percentage by weight: na (Na)⁺5.16g/L、K⁺0.56g/L、NH₄ ⁺1.75g/L、Mg²⁺1.82g/L、SO₄ ^2-8.92g/L, and the stone coal acid wastewater further comprises: 0.055g/L vanadium, 0.0032g/L chromium, 0.0044g/L nickel, 0.021g/L copper, 0.0039g/L cobalt, 0.0013g/L cadmium, 0.0002g/L arsenic, 0.083g/L zinc, 0.086g/L iron, 0.023g/L aluminium, said method including the following steps：

(1) Selectively recovering heavy metals from the stone coal acidic wastewater by using a nitrogen-containing chelate resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, performing multiple times of circulating leaching, evaporating at 90 ℃ and under the vacuum degree of 90kPa, and enriching to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺135g/L、K⁺10.26g/L、Mg²⁺44.85g/L、NH₄ ⁺27.47g/L, adding ammonium sulfate into the enrichment solution, wherein the addition amount of the ammonium sulfate is 1 time of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at 65 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate into the filtrate obtained in the step (2), wherein the adding amount of ferric sulfate is 0.5 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and ammonia water to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about 3 in the reaction process, carrying out precipitation reaction for 6 hours at the temperature of 30 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the concentration of each ion in the filtrate is Na⁺2.26g/L、K⁺0.93g/L、Mg²⁺21.08g/L、NH₄ ⁺4.83g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 98.48 wt%, and the purity of the magnesium-nitrogen double salt was 98.59 wt% through detection and calculation.

Example 2:

the embodiment provides a method for resource utilization of stone coal acidic wastewater, wherein the components and the concentration in the stone coal acidic wastewater refer to embodiment 1, and the method comprises the following steps:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a sulfide precipitator to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, and performing multiple circulating leaching and enrichment to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺15.24g/L、K⁺1.36g/L、Mg²⁺12.33g/L、NH₄ ⁺4.97g/L, adding ammonium bisulfate and magnesium bisulfate into the enrichment solution, wherein the total addition amount of the ammonium bisulfate and the magnesium bisulfate is 2 times of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at the temperature of 0 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric chloride into the filtrate obtained in the step (2), wherein the addition amount of the ferric chloride is 3 times of the theoretical amount required for producing the jarosite, adding hydrochloric acid and sodium hydroxide to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about-2 in the reaction process, carrying out precipitation reaction for 0.2h at 115 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the ion concentration in the filtrate is Na⁺0.69g/L、K⁺0.73g/L、Mg²⁺4.85g/L、NH₄ ⁺1.02g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 98.29 wt% and the purity of the magnesium-nitrogen double salt was 97.42 wt% by detection and calculation.

Example 3:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using an oxygen-containing and sulfur-containing chelate resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, and performing multiple circulating leaching and enrichment to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺126.46g/L、K⁺23.83g/L、Mg²⁺42.89g/L、NH₄ ⁺70g/L, adding magnesium sulfate into the enrichment solution, wherein the addition amount of the magnesium sulfate is 1.2 times of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at 70 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric hydroxide into the filtrate obtained in the step (2), wherein the addition amount of the ferric hydroxide is 0.1 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and sodium carbonate to adjust and control the pH of the solution, so that the solution is maintained at about 4 in the reaction process, carrying out precipitation reaction for 7 hours at the temperature of 50 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the concentration of each ion in the filtrate is Na⁺3.02g/L、K⁺1.96g/L、Mg²⁺16.92g/L、NH₄ ⁺5.05g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 98.97 wt%, and the purity of the magnesium-nitrogen double salt was 98.83 wt%.

Example 4:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a nitrogen-containing and phosphorus-containing chelate resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) evaporating the solution obtained in the step (1) at the temperature of 80 ℃ and the vacuum degree of 80kPa, and enriching to obtain a high-concentration salt-containing solution, wherein the concentration of each ion in the high-concentration salt-containing solution is Na⁺44.22g/L、K⁺4.81g/L、Mg²⁺15.48g/L、NH₄ ⁺15.46g/L, adding ammonium chloride and ammonium nitrate into the enrichment solution, wherein the addition amount of the ammonium chloride and the ammonium nitrate is 0.2 times of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at the temperature of 10 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate and ferric hydroxide into the filtrate obtained in the step (2), wherein the addition amount of the ferric sulfate and the ferric hydroxide is 1 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and potassium hydroxide to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about 0.5 in the reaction process, carrying out precipitation reaction for 1h at the temperature of 125 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the concentration of each ion in the filtrate is Na⁺1.72g/L、K⁺0.99g/L、Mg²⁺6.27g/L、NH₄ ⁺1.29g/L, returning the filtrate to the stone coal leaching process for circular treatment, and precipitating the jarosite into a mixture of jarosite, ammoniojarosite and jarosite, washing with water, deacidifying, and directly burying.

In this example, the purity of the obtained magnesium-nitrogen double salt product was 98.95 wt% by detection and calculation.

Example 5:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a phosphorus-containing chelating resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, performing multiple times of circulating leaching, evaporating at 70 ℃ under the condition of vacuum degree of 40kPa, and enriching to obtain high-concentrationA salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺85.92g/L、K⁺5.57g/L、Mg²⁺30g/L、NH₄ ⁺25.94g/L, adding ammonium bisulfate into the enrichment solution, wherein the addition amount of the ammonium bisulfate is 0.8 times of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at the temperature of 50 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding iron-rich minerals and iron-rich tailings into the filtrate obtained in the step (2), wherein the addition amount of the iron-rich minerals and the iron-rich tailings is 0.85 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and ammonia water to adjust and control the pH of the solution, maintaining the pH of the solution at about 1.3 in the reaction process, carrying out precipitation reaction for 2 hours at the temperature of 110 ℃, and filtering to obtain jarosite precipitates and filtrate, wherein the ion concentration of each filtrate is Na⁺1.91g/L、K⁺0.79g/L、Mg²⁺13.95g/L、NH₄ ⁺1.81g/L, returning the filtrate to the stone coal leaching process for circular treatment, and precipitating the jarosite into a mixture of jarosite, ammoniojarosite and jarosite, washing with water, deacidifying, and directly burying.

In this example, the purity of the magnesium nitrogen double salt product obtained by detection and calculation is 97.91 wt%.

Example 6:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a sulfur-containing chelating resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, and performing multiple circulating leaching and enrichment to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺133.84g/L、K⁺16.25g/L、Mg²⁺43.87g/L、NH₄ ⁺50g/L, adding ammonium carbonate and ammonium bicarbonate into the enrichment solution, wherein the adding amount is to generate magnesium-nitrogen complexCrystallizing 0.6 times of the theoretical amount of salt at 60 deg.C, and filtering to obtain magnesium-nitrogen double salt and filtrate;

(3) adding ferric oxide into the filtrate obtained in the step (2), wherein the addition amount of ferric oxide is 0.7 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and potassium hydroxide to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about 2 in the reaction process, carrying out precipitation reaction for 6 hours at the temperature of 60 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the concentration of each ion in the filtrate is Na⁺2.39g/L、K⁺1.61g/L、Mg²⁺19.44g/L、NH₄ ⁺2.88g/L, returning the filtrate to the stone coal leaching process for circular treatment, precipitating the jarosite into a mixture of jarosite, ammonioiarosite and jarosite, washing the jarosite with water, deacidifying, and directly burying.

In this example, the purity of the magnesium nitrogen double salt product obtained by detection and calculation is 98.14 wt%.

Example 7:

the embodiment provides a method for resource utilization of stone coal acidic wastewater, which comprises the following main components in percentage by weight: na (Na)⁺6.52g/L、K⁺0.73g/L、NH₄ ⁺1.92g/L、Mg²⁺1.69g/L、SO₄ ^2-7.49g/L, and the stone coal acid wastewater also comprises: 0.0084g/L of vanadium, 0.017g/L of chromium, 0.0012g/L of nickel, 0.045g/L of copper, 0.0013g/L of cobalt, 0.0007g/L of cadmium, 0.0003g/L of arsenic, 0.069g/L of zinc, 0.072g/L of iron and 0.048g/L of aluminum, wherein the method comprises the following steps:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a chelate resin adsorbent containing nitrogen, phosphorus, oxygen and sulfur to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, and performing multiple circulating leaching and enrichment to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺30.93g/L、K⁺3.27g/L、Mg²⁺7.56g/L、NH₄ ⁺8.85g/L, adding ammonium bicarbonate and magnesium bicarbonate into the enrichment solution, wherein the total addition amount of the ammonium bicarbonate and the magnesium bicarbonate is 2.5 times of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at the temperature of 30 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate and ferric hydroxide into the filtrate obtained in the step (2), wherein the addition amount of the ferric sulfate and the ferric hydroxide is 1.5 times of the theoretical amount required for producing the jarosite, adding sulfuric acid and sodium hydroxide to adjust and control the pH of the solution, so that the solution is maintained at about-1 in the reaction process, carrying out precipitation reaction for 0.8h at the temperature of 150 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the ion concentration of each filtrate is Na⁺0.79g/L、K⁺0.84g/L、Mg²⁺9.63g/L、NH₄ ⁺2.18g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 98.64 wt%, and the purity of the magnesium-nitrogen double salt was 98.18 wt% through detection and calculation.

Example 8:

the embodiment provides a method for resource utilization of stone coal acidic wastewater, wherein the components and the concentration in the stone coal acidic wastewater refer to embodiment 7, and the method comprises the following steps:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a microbial adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, performing multiple times of circulating leaching, evaporating at 60 ℃ and under the vacuum degree of 10kPa, and enriching to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺128.86g/L、K⁺21.29g/L、Mg²⁺45g/L、NH₄ ⁺36.24g/L, adding ammonium bisulfate into the enrichment solution, wherein the addition amount of the ammonium bisulfate is 0.3 time of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at the temperature of 75 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate into the filtrate obtained in the step (2), wherein the adding amount of ferric sulfate is 0.8 time of the theoretical amount required for producing the jarosite, adding sulfuric acid and ammonia water to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about 1.2 in the reaction process, carrying out precipitation reaction for 3h at the temperature of 130 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the concentration of each ion in the filtrate is Na⁺2.88g/L、K⁺1.02g/L、Mg²⁺29.28g/L、NH₄ ⁺1.58g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 98.86 wt% and the purity of the magnesium nitrogen double salt was 99.07 wt% through detection and calculation.

Example 9:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using an oxygen-containing and sulfur-containing chelating resin adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) evaporating the solution obtained in the step (1) at the temperature of 95 ℃ and the vacuum degree of 30kPa, and enriching to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺38.92g/L、K⁺4.46g/L、Mg²⁺10g/L、NH₄ ⁺11.28g/L, adding ammonium sulfate into the enrichment solution, wherein the addition amount of the ammonium sulfate is 1.8 times of the theoretical amount required for generating the magnesium-nitrogen double saltCrystallizing at 40 deg.C, and filtering to obtain magnesium-nitrogen double salt and filtrate;

(3) adding ferric oxide into the filtrate obtained in the step (2), wherein the addition amount of ferric oxide is 0.99 times of the theoretical amount required for producing the jarosite, adding sulfuric acid and potassium hydroxide to adjust and control the pH of the solution, so that the pH value of the solution is maintained at about 0.3 in the reaction process, carrying out precipitation reaction for 1.5h at the temperature of 101 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the ion concentration in the filtrate is Na⁺1.87g/L、K⁺0.94g/L、Mg²⁺8.75g/L、NH₄ ⁺2.23g/L, returning the filtrate to the stone coal leaching process for cyclic treatment, precipitating the jarosite into a mixture of the jarosite, the ammoniojarosite and the jarosite, recovering ammonia gas and sulfur trioxide generated by roasting the jarosite to obtain an ammonium sulfate solution, and washing the roasted material with water to obtain an iron oxide product and an alkali metal sulfate solution.

In this example, the purity of the obtained iron oxide product was 99.28 wt% and the purity of the magnesium-nitrogen double salt was 97.82 wt% by detection and calculation.

Example 10:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a chelate resin adsorbent containing nitrogen, phosphorus and sulfur to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, performing multiple times of circulating leaching, evaporating at 100 ℃ and under the vacuum degree of 60kPa, and enriching to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺84.59g/L、K⁺21.29g/L、Mg²⁺22.37g/L、NH₄ ⁺25.74g/L, adding ammonium sulfate and ammonium bisulfate into the enrichment solution, wherein the addition amount of the ammonium sulfate and the ammonium bisulfate is 1.1 times of the theoretical amount required for generating the magnesium-nitrogen double salt, and carrying out treatment at 5 DEG CCrystallizing under the condition of one-step crystallization, and filtering to obtain magnesium-nitrogen double salt and filtrate;

(3) adding ferric hydroxide and ferric oxide into the filtrate obtained in the step (2), wherein the addition amount of the ferric hydroxide and the ferric oxide is 1.8 times of the theoretical amount required for producing the jarosite, adding sulfuric acid and sodium hydroxide to adjust and control the pH of the solution, maintaining the pH value of the solution at about 0.8 in the reaction process, carrying out precipitation reaction for 4 hours at the temperature of 80 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the ion concentration of each filtrate is Na⁺1.27g/L、K⁺1.82g/L、Mg²⁺4.02g/L、NH₄ ⁺1.18g/L, returning the filtrate to the stone coal leaching process for circular treatment, precipitating the jarosite into a mixture of jarosite, ammoniojarosite and jarosite, washing with water, deacidifying, and directly burying.

In this example, the purity of the obtained magnesium-nitrogen double salt product was 97.68 wt% by detection and calculation.

Example 11:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using a natural biological adsorbent to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) evaporating the solution obtained in the step (1) at the temperature of 85 ℃ and the vacuum degree of 50kPa, and enriching to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺78.33g/L、K⁺8.67g/L、Mg²⁺20g/L、NH₄ ⁺23.07g/L, adding ammonium sulfate into the enrichment solution, wherein the addition amount of the ammonium sulfate is 0.9 time of the theoretical amount required for generating the magnesium-nitrogen double salt, crystallizing at 25 ℃, and filtering to obtain the magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate into the filtrate obtained in the step (2), wherein the adding amount of the ferric sulfate is 2 times of the theoretical amount required for producing the jarosite, adding sulfuric acid and potassium hydroxide to adjust and control the pH value of the solution, so that the solution is reactedMaintaining at about 1 deg.C, precipitating at 200 deg.C for 1.2 hr, filtering to obtain jarosite precipitate and filtrate, wherein each ion concentration in the filtrate is Na⁺3.98g/L、K⁺1.24g/L、Mg²⁺8.36g/L、NH₄ ⁺1.68g/L, returning the filtrate to the stone coal leaching process for circular treatment, precipitating the jarosite into a mixture of jarosite, ammoniojarosite and jarosite, washing with water, deacidifying, and directly burying.

In this example, the purity of the magnesium nitrogen double salt product obtained by detection and calculation is 98.52 wt%.

Example 12:

(1) selectively recovering heavy metals from the stone coal acidic wastewater by using oxygen-containing and phosphorus-containing chelating resin adsorbents to obtain a heavy metal concentrate and a solution, wherein the concentrations of vanadium, chromium, nickel, copper, cobalt, cadmium, zinc, iron and aluminum in the solution are all less than 0.1ppm, and the heavy metal concentrate is separated and recovered according to the prior art;

(2) returning the solution obtained in the step (1) to the stone coal leaching process, performing multiple times of circulating leaching, evaporating at 80 ℃ and 70kPa to obtain a high-concentration salt-containing solution, wherein each ion concentration in the high-concentration salt-containing solution is Na⁺90g/L、K⁺9.77g/L、Mg²⁺23.21g/L、NH₄ ⁺24.57g/L, crystallizing at 20 ℃, and filtering to obtain magnesium-nitrogen double salt and filtrate;

(3) adding ferric sulfate, ferric oxide and ferric hydroxide into the filtrate obtained in the step (2), wherein the adding amount of the ferric sulfate, the ferric oxide and the ferric hydroxide is 0.95 times of the theoretical amount required for producing the jarosite, adding sulfuric acid and sodium hydroxide to adjust and control the pH of the solution, maintaining the pH of the solution at about 0 in the reaction process, carrying out precipitation reaction for 2 hours at 105 ℃, and filtering to obtain jarosite precipitate and filtrate, wherein the ion concentration of each filtrate is Na⁺1.25g/L、K⁺0.91g/L、Mg²⁺7.04g/L、NH₄ ⁺0.74g/L, and the filtrate returns to the stone coalThe leaching process is circulated, the jarosite is precipitated into a mixture of the jarosite, the ammoniojarosite and the jarosite, and the mixture is washed with water to deacidify and then is directly buried.

In this example, the purity of the obtained magnesium-nitrogen double salt product was 98.62 wt% by detection and calculation.

By integrating the above embodiments, the stone coal acidic wastewater is separated and recovered with heavy metal ions, and then magnesium-nitrogen double salt and jarosite are respectively obtained by a multi-step crystallization method, so that high-efficiency separation and recovery of different components in the wastewater are realized, various products with high added values are obtained, the product purity is high, no heavy metal is entrained, the wastewater is returned to the stone coal leaching process after treatment, and zero discharge of the wastewater is realized; the method has the advantages of low cost, simple operation, cleanness, environmental protection and the like.

The applicant states that the process of the present invention is illustrated by the above examples, but the present invention is not limited to the above process, i.e. it is not meant that the present invention must rely on the above process to be carried out. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims

1. A method for resource utilization of stone coal acidic wastewater is characterized by comprising the following steps:

(1) recovering heavy metal ions in stone coal acidic wastewater, wherein the stone coal acidic wastewater is stone coal sulfuric acid process vanadium extraction process wastewater, the heavy metal ions are recovered by adopting an adsorption method or a precipitation method, an adsorbent used by the adsorption method is chelate resin and/or a biological adsorbent, a precipitator used by the precipitation method is sulfide, and a heavy metal concentrate and a solution are obtained, wherein the heavy metal concentrate comprises a combination of at least two of vanadium, chromium, iron, cobalt, nickel, copper, zinc or cadmium;

(2) enriching the solution obtained in the step (1) to obtain a high-concentration salt-containing solution containing Mg²⁺、Na⁺、K⁺And NH₄ ⁺Adding ammonium salt and/or magnesium salt, and crystallizing to obtain magnesium-nitrogen double salt and solution; the addition amount of the ammonium salt and/or the magnesium salt is MgSO (MgSO) used for generating magnesium-nitrogen double salt₄·(NH₄)₂SO₄·6H₂0-2.5 times of theoretical amount of O; the ammonium salt comprises ammonium sulfate and/or ammonium bisulfate, and the magnesium salt comprises magnesium sulfate and/or magnesium bisulfate;

2. The method according to claim 1, wherein the stone coal acidic wastewater in the step (1) does not contain Cl^－And F^－。

3. The method as claimed in claim 1, wherein the pH of the stone coal acidic wastewater in the step (1) is less than 7.

4. The method according to claim 3, wherein the pH of the stone coal acidic wastewater in the step (1) is 0-6.

5. The method of claim 1, wherein the heavy metal ion recovery in step (1) is performed by adsorption.

6. The method of claim 1, wherein the functional groups of the chelating resin comprise any one of or a combination of at least two of nitrogen-containing functional groups, phosphorus-containing functional groups, oxygen-containing functional groups, or sulfur-containing functional groups.

7. The method according to claim 6, wherein the functional group of the chelating resin is a nitrogen-containing functional group and/or a phosphorus-containing functional group.

8. The method of claim 1, wherein the biological adsorbent comprises any one or a combination of at least two of natural organic adsorbents and modifications thereof, microorganisms and modifications thereof, or agricultural, forestry, animal husbandry and fishery waste and modifications thereof.

9. The method of claim 1, wherein the sulfide comprises any one of sodium sulfide, potassium sulfide, ammonium sulfide, sodium hydrosulfide, potassium hydrosulfide, or ammonium hydrosulfide, or a combination of at least two thereof.

10. The method of claim 1, wherein the concentrate of step (1) further comprises aluminum and arsenic.

11. The method according to claim 1, wherein the enrichment method in step (2) comprises any one of recycling leaching, evaporative concentration or evaporative concentration after recycling leaching in the stone coal leaching process.

12. The method according to claim 11, wherein the enrichment method in the step (2) is to return to the stone coal leaching process for cyclic leaching and then evaporation concentration.

13. The method according to claim 11, wherein the evaporation concentration treatment is reduced pressure evaporation, and the vacuum degree of the reduced pressure evaporation is 10-90 kPa.

14. The method according to claim 11, wherein the temperature of the evaporative concentration treatment is 60 to 100 ℃.

15. The method according to claim 11, wherein the steam obtained from the evaporative concentration treatment is condensed and used in the process of extracting vanadium from stone coal.

16. The method of claim 1, wherein step (2) comprises adding Mg to the high-concentration salt-containing solution²⁺The concentration is 10-45 g/L。

17. The method of claim 16, wherein step (2) comprises adding Mg to the high-concentration salt-containing solution²⁺The concentration is 20-30 g/L.

18. The method of claim 1, wherein the high concentration salt-containing solution of step (2) contains Na⁺The concentration is less than or equal to 135 g/L.

19. The method of claim 18, wherein the high concentration salt-containing solution of step (2) contains Na⁺The concentration is less than or equal to 90 g/L.

20. The method of claim 1, wherein K is present in the high concentration salt-containing solution of step (2)⁺The concentration is less than or equal to 80 g/L.

21. The method of claim 20, wherein the K in the high concentration salt-containing solution of step (2)⁺The concentration is less than or equal to 55 g/L.

22. The method of claim 1, wherein the NH in the high-concentration salt-containing solution of step (2)₄ ⁺The concentration is less than or equal to 70 g/L.

23. The method of claim 22, wherein the step (2) of providing NH in the high-strength salt-containing solution₄ ⁺The concentration is less than or equal to 50 g/L.

24. The method of claim 1, wherein the ammonium salt of step (2) comprises any one of ammonium nitrate, ammonium carbonate or ammonium bicarbonate or a combination of at least two thereof.

25. The method of claim 24, wherein the ammonium salt of step (2) comprises ammonium carbonate and/or ammonium bicarbonate.

26. The method of claim 1, wherein the magnesium salt in step (2) comprises any one of magnesium nitrate, magnesium carbonate, magnesium bicarbonate, or basic magnesium carbonate, or a combination of at least two of them.

27. The method of claim 26, wherein the magnesium salt of step (2) comprises magnesium carbonate and/or magnesium bicarbonate.

28. The method of claim 1, wherein the ammonium salt and/or magnesium salt of step (2) is added in an amount to produce magnesium nitrogen double salt (MgSO)₄·(NH₄)₂SO₄·6H₂O is 0.2 to 1.2 times of the theoretical amount required.

29. The method according to claim 1, wherein the temperature of the crystallization in the step (2) is 0 to 70 ℃.

30. The method according to claim 29, wherein the temperature of the crystallization in the step (2) is 10 to 60 ℃.

31. The method according to claim 29, wherein the temperature of the crystallization in the step (2) is 20 to 40 ℃.

32. The method according to claim 1, wherein the magnesium-nitrogen double salt of step (2) is used as a magnesium-nitrogen compound fertilizer.

33. The method as claimed in claim 1, wherein the magnesium nitrogen double salt of step (2) is used in agricultural production and/or forestry production.

34. The method of claim 1, wherein the iron-containing substance of step (3) comprises any one of iron sulfate, iron nitrate, iron hydroxide, iron oxide, iron-rich minerals or iron-rich tailings or a combination of at least two thereof.

35. The method of claim 34, wherein the iron-containing material of step (3) comprises any one of iron sulfate, iron hydroxide, or iron oxide, or a combination of at least two thereof.

36. The method of claim 35, wherein the iron-containing species of step (3) comprises iron sulfate.

37. The method according to claim 1, wherein the iron-containing material added in step (3) is 0.1 to 3 times the theoretical amount required for producing jarosite.

38. The method according to claim 37, wherein the iron-containing material of step (3) is added in an amount of 0.5 to 1.5 times the theoretical amount required for producing jarosite.

39. The method according to claim 38, wherein the iron-containing material of step (3) is added in an amount of 0.8 to 1 times the theoretical amount required for producing jarosite.

40. The method of claim 1, wherein the composition of said jarosite of step (3) is MFe₃(SO₄)₂(OH)₆Wherein M is Na⁺、NH₄ ⁺Or K⁺Any one or a combination of at least two of them.

41. The method according to claim 1, wherein the precipitation reaction in step (3) has a pH of-2 to 4.

42. The method according to claim 41, wherein the precipitation reaction in step (3) has a pH of-1 to 3.

43. The method according to claim 42, wherein the precipitation reaction in step (3) has a pH of 0 to 1.3.

44. The method of claim 41, wherein the pH is adjusted with an acidic or basic substance.

45. The method of claim 44, wherein the acidic material comprises nitric acid and/or sulfuric acid.

46. The method of claim 45, wherein the acidic material comprises sulfuric acid.

47. The method of claim 44, wherein the alkaline substance comprises any one of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, or potassium bicarbonate, or a combination of at least two thereof.

48. The method of claim 44, wherein the alkaline substance comprises any one of sodium hydroxide, potassium hydroxide, or ammonia, or a combination of at least two thereof.

49. The method according to claim 1, wherein the precipitation reaction in step (3) is carried out at a temperature of 30 to 200 ℃.

50. The method as claimed in claim 49, wherein the precipitation reaction in step (3) is carried out at a temperature of 60-150 ℃.

51. The method according to claim 50, wherein the precipitation reaction in step (3) is carried out at a temperature of 101-150 ℃.

52. The method according to claim 1, wherein the precipitation reaction time in the step (3) is 0.2-8 h.

53. The method as claimed in claim 52, wherein the precipitation reaction time in step (3) is 0.5-6 h.

54. The method according to claim 53, wherein the precipitation reaction time in step (3) is 1-4 h.

55. The method of claim 1, wherein the jarosite precipitate of step (3) is used for recovery of valuable components or for landfill disposal.

56. The process of claim 55, wherein said jarosite precipitate is recovered as an ammonium sulfate solution, ferric oxide and an alkali metal sulfate solution.

57. The method as claimed in claim 56, wherein the ammonium sulfate solution is used in the process of vanadium extraction from stone coal and/or returned to step (2) for preparing magnesium nitrogen double salt.

58. The method of claim 56, wherein the iron oxide is returned to step (3) as an iron-containing material.

59. Method according to claim 1, characterized in that it comprises the following steps:

(1) recovering heavy metal ions in stone coal acidic wastewater by adopting an adsorption method or a precipitation method, wherein the stone coal acidic wastewater is stone coal sulfuric acid method vanadium extraction process wastewater, an adsorbent used by the adsorption method is a chelating resin and/or a biological adsorbent, a precipitator used by the precipitation method is a sulfide, and a heavy metal concentrate and a solution are obtained, wherein the heavy metal concentrate comprises a combination of at least two of vanadium, chromium, iron, cobalt, nickel, copper, zinc or cadmium;

(2) returning the solution obtained in the step (1) to the stone coal leaching process for cyclic leaching, and then carrying out evaporation concentration and enrichment, wherein the vacuum degree of evaporation concentration treatment is 10-90 kPa, the temperature is 60-100 ℃, and the solution obtained after enrichment is obtainedHigh concentration salt solutions containing Mg²⁺、Na⁺、K⁺And NH₄ ⁺Then adding ammonium salt and/or magnesium salt in an amount to generate magnesium nitrogen double salt MgSO₄·(NH₄)₂SO₄·6H₂O is 0-2.5 times of the theoretical amount required by the reaction, the ammonium salt comprises ammonium sulfate and/or ammonium bisulfate, the magnesium salt comprises magnesium sulfate and/or magnesium bisulfate, and the crystallization is carried out at the temperature of 0-70 ℃ to obtain magnesium-nitrogen double salt and solution;