A method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions

Abstract

The present invention belongs to the field of hydrometallurgy technology, and specifically relates to a method for recovering ammonia and nitrogen from ammonium molybdate mother liquor and removing other impurity ions. The method comprises: extracting the ammonium molybdate mother liquor and performing oil separation to produce an ammonia recovery stock solution; neutralizing and filtering the ammonia recovery stock solution to obtain a neutralized filtrate; deeply decalcifying the neutralized filtrate to obtain a decalcified filtrate; steam stripping the decalcified filtrate to recover ammonia; recovering ammonia from the non-condensable gas produced in the overhead condenser after steam stripping and the steam produced during the neutralization process; and heat exchanging the deeply impurity-removed purified liquid produced at the bottom of the steam stripping tower and the oil-separated ammonia recovery stock solution, cooling them, and then transferring them to the production system for reuse. The present invention can effectively recover ammonia and nitrogen resources from the ammonium molybdate mother liquor, deeply remove other impurity ions in the solution, eliminate the blockage effect of CaSO4 scale on pipelines and heat exchangers, improve the Mo leaching rate, and reduce the three-phase product yield and organic phase loss.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions. Background Art

[0002] Molybdenum and its alloys are widely used in fields such as metallurgy, electronics and electrical engineering, chemical engineering, environmental protection, and aerospace. They are important mineral resources indispensable for my country's economic development and scientific research. With the development of my country's economy, the demand for molybdenum and molybdenum products in various industries will inevitably continue to increase. As a strategic mineral resource, molybdenum has poor flotation performance in some low-grade ores due to differences in mineral properties. Therefore, it is particularly important to develop and optimize the smelting and purification technologies of low-grade, complex, and polymetallic molybdenum ores to achieve improved comprehensive molybdenum metal recovery and the recovery of polymetallic compounds associated with molybdenum ores.

[0003] A domestic enterprise carried out indoor condition tests, pilot tests and expanded tests on the oxygen pressure leaching process technology for uranium-molybdenum co-existing raw ore, and finally realized the industrial application of the raw ore oxygen pressure leaching process technology. After the application of this technology, the molybdenum leaching rate increased from 33% to 36% of conventional leaching to more than 85%, improving the comprehensive recovery rate of molybdenum resources and doubling the production capacity. Because the production process water of the enterprise adopts a closed-loop circulation method, during the production operation, K in the circulating water + 、Na + NH4 + 、Fe 3+ 、Al 3+ , Ca 2 + Mg 2+ 、SO4 2- The concentration of impurity ions is high, and the molybdenum leaching rate shows a downward trend with the increase of impurity ion concentration. In severe cases, it is reduced by more than 10% compared with the early stage of industrialization. + The cations have the greatest influence on the leaching rate of Mo in oxygen pressure leaching. + When the concentration dropped from 8g / L to 12g / L and below 2g / L, the Mo leaching rate basically returned to the initial level of industrial application. + The ions mainly come from the molybdenum back extraction qualified liquid in the production process of ammonium molybdate, and are finally collected in the ammonium molybdate acid precipitation product and acid precipitation mother liquor. According to the analysis of the acid precipitation mother liquor, the NH4 + Ion concentration is 55g / L~80g / L, SO4 2- The ion concentration is 190g / L~230g / L.

[0004] Due to the low precipitation rate of ammonium molybdate, the mother liquor of sulfuric acid precipitation still contains 8-20g / L of molybdenum. For the recovery of Mo from the mother liquor of ammonium molybdate precipitation, the more commonly used methods in the industry include selective precipitation, ion exchange, extraction, and activated carbon adsorption. Considering the maturity of the process technology and compatibility with existing process systems, this company adopted a solvent extraction method, using a mixture of 6-9wt% tri-fatty amine or trioctylamine, 10-20wt% tributyl phosphate, and 75-80wt% sulfonated kerosene to recover the molybdenum metal. The extracted organic phase enters the existing stripping system, and the raffinate enters the evaporation tank. This method can effectively recover the molybdenum in the mother liquor of sulfuric acid precipitation, reducing the molybdenum concentration in the raffinate of the mother liquor of sulfuric acid precipitation to below 20mg / L, and achieving a recovery rate of over 99.3%. However, when the raffinate of sulfuric acid precipitation mother liquor is returned to oxygen pressure leaching for recycling, the molybdenum leaching rate decreases with the increase of impurity ion concentration due to the presence of impurity ions in the raffinate, which seriously affects the molybdenum leaching rate of oxygen pressure leaching. + If ammonia water with a concentration of 13% to 18% can be recovered, it can be used as a stripping agent in the molybdenum stripping process, thereby comprehensively utilizing the ammonia nitrogen resources in the raffinate of the sulfuric acid precipitation mother liquor. Therefore, in order to return the sulfuric acid precipitation mother liquor raffinate after molybdenum recovery to the production system, avoid affecting the molybdenum leaching rate of complex molybdenum ore oxygen pressure leaching, and at the same time recover the ammonia nitrogen resources in the sulfuric acid precipitation mother liquor raffinate, it is urgent to develop a method for recovering ammonia nitrogen and removing other impurity ions from the ammonium molybdate precipitation mother liquor. Summary of the Invention

[0005] The object of the present invention is to provide a method for removing ammonia nitrogen and other impurity ions from ammonium molybdate acid precipitation mother liquor. The method can effectively recover ammonia nitrogen resources in ammonium molybdate acid precipitation mother liquor, deeply remove other impurity ions in the solution, solve the blocking effect of CaSO4 scale on pipelines and heat exchangers, further improve the Mo leaching rate of the front-end leaching process, and reduce the three-phase material output and organic phase loss of the front-end extraction process.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] A method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions, the method comprising the following steps:

[0008] Step (1), extracting the ammonium molybdate sulfuric acid precipitation mother liquor using an extraction system of a mixture of 6-9 wt% trifatty amine or trioctylamine, 10-20 wt% tributyl phosphate and 75-80 wt% sulfonated kerosene to obtain raffinate;

[0009] Step (2), separating the raffinate from the oil, recovering the organic phase to obtain an aqueous phase, and subjecting the aqueous phase to deep adsorption and oil removal by activated carbon, i.e., ammonia recovery stock solution;

[0010] Step (3), adding a neutralizing agent to the ammonia recovery stock solution, neutralizing and filtering to obtain a neutralized filtrate, and discarding the filter residue;

[0011] Step (4), deep decalcifying the neutralized filtrate with carbonate to obtain a decalcified filtrate, and the filter residue is discarded and stored;

[0012] Step (5) steam stripping the decalcified filtrate, the bottom of the liquid ammonia vapor tower is the purified liquid after deammoniation and impurity removal; the top of the liquid ammonia vapor tower is a mixed steam of ammonia and water vapor; the mixed steam at the top of the tower is condensed in a condenser to recover ammonia;

[0013] Step (6), absorbing the non-condensable gas generated in the top condenser after steam stripping, the steam generated in the neutralization process and the process water in an absorption tower, and recovering the non-condensable gas and ammonia entrained in the neutralization steam;

[0014] Step (7) heat exchange is performed on the purified liquid after deep impurity removal produced at the bottom of the tower after steam stripping and the ammonia recovery liquid after oil separation, and after cooling, the liquid is collected into the production system for reuse in the upstream process.

[0015] In the step (1), molybdenum resources are recovered from the ammonium molybdate sulfuric acid precipitation mother liquor, 8g / L to 20g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the molybdenum concentration in the raffinate tail liquid is ≤50mg / L, and the molybdenum resource recovery rate reaches more than 99.3%.

[0016] In the step (2), the raffinate water is subjected to oil separation and deep oil removal treatment by activated carbon adsorption, and the oil content in the aqueous phase obtained after the treatment is controlled to be ≤30 mg / L.

[0017] The neutralizing agent added in step (3) is a calcium alkaline substance, and the calcium alkaline substance includes: CaO, Ca(OH)2, and carbide slag.

[0018] In the step (3), a neutralizing agent is added to the raffinate water to adjust the pH value to 11-13.

[0019] The amount of the neutralizer added in step (3) is based on the amount of Ca in the raffinate water. 2+ Mg 2+ 、Fe 3+ 、Al 3+ 、SO4 2- Concentration difference addition 70~130kg / m 3 Neutralizer, stirring time is 1 to 2 hours, and solid-liquid separation is performed using a plate and frame filter press.

[0020] The concentration of the carbonate solution added for deep decalcification in step (4) is 10% to 15%. After reacting for 1 to 2 hours, solid-liquid separation is performed using a plate and frame filter press.

[0021] After deep decalcification in step (4), Ca 2+ The concentration is reduced to 0.002g / L~0.003g / L, and the calcium removal rate in this step is greater than 99.5%.

[0022] In the step (5), the mixed steam of ammonia gas and water vapor at the top of the liquid ammonia distillation tower is condensed in the tower top condenser to produce 13% to 18% ammonia water, which is reused as a stripping agent in the molybdenum stripping process.

[0023] In the step (6), the ammonia water with a concentration of 13% to 18% obtained by absorption in the absorption tower in (5) is combined with the mixed steam at the top of the tower after steam stripping and condensed in a condenser to recover ammonia, and the ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 .

[0024] After heat exchange in step (7), the water is cooled to 15°C to 20°C and then returned to the process water system for use.

[0025] The beneficial technical effects of the present invention are:

[0026] 1. The present invention provides a method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions. The steam stripping ammonia recovery system is used to make the concentration of recovered ammonia water reach between 13% and 18%, meeting the process reuse requirements. After steam stripping ammonia recovery, NH4 + Concentration ≤ 0.5g / L, removal rate 99.1%; ammonia nitrogen concentration discharged from the non-condensable steam absorption tower ≤ 20mg / m 3 , meeting environmental protection requirements.

[0027] 2. The present invention provides a method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions. The method uses an alkaline neutralizer and a carbonate deep decalcification method to remove Ca in the molybdenum raffinate tail liquid recovered from the sulfuric acid precipitation mother liquor. 2+ Mg 2+ 、Fe 3+ 、Al 3+ Cations and SO4 2- Anion, Ca 2+ Concentration ≤ 0.0031 g / L, removal rate 84.5%; Mg 2+ Concentration ≤ 0.004g / L, removal rate 99.7%; Al 3+ Concentration ≤ 0.0003g / L, removal rate 99.99%; Fe 3+ Trace concentration, removal rate 99.99%; SO4 2- The concentration is ≤1.36g / L, and the removal rate is 99.28%. It effectively removes ammonia nitrogen and its impurity ions in the raffinate of molybdenum recovery from sulfuric acid precipitation mother liquor. At the same time, it effectively avoids the impact of calcium scale on heat exchange equipment and process pipelines, ensures heat exchange efficiency, and avoids blockage of process pipelines.

[0028] 3. The present invention provides a method for recovering ammonia nitrogen and removing other impurity ions from ammonium molybdate precipitation mother liquor. The sulfuric acid precipitation mother liquor is subjected to recycling of ammonia nitrogen resources and removal of other impurity ions, and then merged into the production process circulating water, which is reused in the oxygen pressure leaching process as leaching agent configuration water. Since ammonia nitrogen and other impurity ions are effectively separated, the molybdenum leaching rate is restored from 78% to 83% to 88% to 92%, and the molybdenum leaching rate is increased by about 7 to 10 percentage points. The output of the three-phase material in the extraction process is reduced by more than 50%, and the consumption of the extracted organic phase is reduced by 20% to 50%. While ensuring the effective recovery of molybdenum resources, the production cost is further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention provides a flow chart of a method for removing ammonia nitrogen and other impurity ions from ammonium molybdate precipitation mother liquor. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] The extraction system of "a mixture of 6-9 wt% trialiphatic amine or trioctylamine, 10-20 wt% tributyl phosphate and 75-80 wt% sulfonated kerosene" was used to recover molybdenum metal. The composition of the raffinate obtained is shown in Table 1.

[0032] Table 1 Sulfuric acid precipitation mother liquor raffinate composition analysis data

[0033]

[0034]

[0035] In view of the fact that the raffinate of sulfuric acid precipitation mother liquor contains a large amount of ammonia nitrogen and other impurity ions, the present invention carries out research and industrial application of the removal method of ammonia nitrogen and other impurity ions in sulfuric acid precipitation mother liquor. + Removal methods include ion exchange technology, evaporation crystallization technology, membrane separation technology, steam stripping technology, bipolar membrane electrolysis technology, etc. Among them, evaporation crystallization technology and steam stripping technology are the most mature; for Ca 2+ Mg 2+ 、Al 3+ 、Fe 3+ Cationic impurities such as ions are neutralized and carbonates are used to remove Ca in depth. 2+ Combined method can effectively remove SO4 2-In the neutralization process, it is removed in the form of CaSO4. Through a comprehensive comparison of the compatibility, technical maturity and economic efficiency of existing processes, a method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions has been formed. The method of the present invention is to apply the method of removing other impurity ions from sulfuric acid acid precipitation mother liquor by neutralizing with alkali (lime, carbide slag, calcium hydroxide and other low-cost calcium-containing alkaline substances), and to deeply remove Ca from the liquid phase after alkali removal by using carbonate. 2+ The application of this method can achieve the purpose of Ca2+ in sulfuric acid precipitation mother liquor. 2+ Mg 2+ 、Al 3+ 、Fe 3+ Cationic impurities and SO4 2- 、F - Anionic impurities such as Ca 2+ 、SO4 2- The Ca in the recycled water after impurity removal is deeply removed. 2+ The ion concentration is reduced to 0.002g / L~0.003g / L, and the removal rate is greater than 85%, SO4 2- The ion concentration is reduced from 190g / L to 230g / L to 0.9g / L to 1.3g / L, and the removal rate is greater than 99.3%, which effectively solves the problem of Ca 2+ Incomplete removal will form CaSO4 scale during the reuse process, causing blockage of process pipelines and heat exchange equipment. The cold residue after impurity removal and heat exchange will be merged into the recycled water of the raw water treatment process and used as the recycled water of the process system. The application of steam stripping to recover ammonia nitrogen resources will convert NH4 + The ion concentration is reduced from 55g / L to 80g / L to 0.3g / L to 0.5g / L, with a recovery rate greater than 99%. The ammonia water with a concentration of 13% to 18% after stripping is reused in the molybdenum stripping process. Compared with the traditional hot air stripping method, it has the advantages of simple equipment structure and short process. The non-condensable gas is absorbed twice by the absorption tower, and the ammonia nitrogen concentration discharged from the top of the tower is less than 20mg / m 3 The features of external discharge and obvious environmental protection benefits are as follows; at the same time, due to the sulfuric acid precipitation of Ca in the mother liquor 2+ Mg 2+ 、Al 3+ 、Fe 3+ Cationic impurities and SO4 2- 、F -Anionic impurities such as anions are effectively removed, and ammonia nitrogen resources are effectively recovered and reused, avoiding the circular accumulation of various anions and cations in the process reuse water, ensuring the water quality of the process reuse water, and providing positive beneficial effects on the front-end leaching process and extraction process. The molybdenum leaching rate is increased from 80% to 84% to 90% to 94%, the production of three-phase products during molybdenum back-extraction is reduced by 45% to 70%, and the loss of organic phase is reduced by 25% to 50%, with obvious economic benefits.

[0036] like Figure 1 As shown, the present invention provides a method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions, which specifically includes the following steps:

[0037] Step (1), extracting the ammonium molybdate sulfuric acid precipitation mother liquor using an extraction system of a mixture of 6-9 wt% trifatty amine or trioctylamine, 10-20 wt% tributyl phosphate and 75-80 wt% sulfonated kerosene to obtain raffinate;

[0038] Step (2), separating the raffinate from the oil, recovering the organic phase to obtain an aqueous phase, and subjecting the aqueous phase to deep adsorption and oil removal by activated carbon, i.e., ammonia recovery stock solution;

[0039] Step (3), adding a neutralizing agent to the ammonia recovery stock solution, neutralizing and filtering to obtain a neutralized filtrate, and discarding the filter residue;

[0040] Step (4), deep decalcifying the neutralized filtrate with carbonate to obtain a decalcified filtrate, and the filter residue is discarded and stored;

[0041] Step (5) steam stripping the decalcified filtrate, the bottom of the liquid ammonia vapor tower is the purified liquid after deammoniation and impurity removal; the top of the liquid ammonia vapor tower is a mixed steam of ammonia and water vapor; the mixed steam at the top of the tower is condensed in a condenser to recover ammonia;

[0042] Step (6) absorbing the non-condensable gas generated in the top condenser after steam stripping, the steam generated in the neutralization process in step (3), and the process water in an absorption tower to recover the non-condensable gas and ammonia entrained in the neutralization steam;

[0043] Step (7) heat exchange is performed on the purified liquid after deep impurity removal produced at the bottom of the tower after steam stripping and the ammonia recovery liquid after oil separation, and after cooling, the liquid is collected into the production system for reuse in the upstream process.

[0044] In step (1) of the embodiment of the present invention, molybdenum resources are recovered from the ammonium molybdate sulfuric acid precipitation mother liquor, 8 g / L to 20 g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the molybdenum concentration in the raffinate tail liquid is ≤50 mg / L, and the molybdenum resource recovery rate reaches more than 99.3%.

[0045] In step (2) of the embodiment of the present invention, the raffinate water is subjected to oil separation and deep adsorption removal by activated carbon, and the oil content in the separated water phase is controlled to be ≤30 mg / L.

[0046] The neutralizing agent added in step (3) of the embodiment of the present invention is a calcium alkaline substance, which includes: CaO, Ca(OH)2, and carbide slag. After adding the neutralizing agent to the raffinate water, the pH value is adjusted to 11-13. The amount of the neutralizing agent added is based on the Ca content in the raffinate water. 2+ Mg 2+ 、Fe 3+ 、Al 3+ 、SO4 2- Concentration difference addition 70~130kg / m 3 Neutralizer, stirring time is 1 to 2 hours, use plate and frame filter press for solid-liquid separation. After neutralization and impurity removal, SO4 2- The removal rate of Ca2+ was reduced from 190g / L to 230g / L to 0.9g / L to 1.3g / L, with a removal rate of more than 99.3%. 2+ The ion concentration is reduced to 0.002g / L~0.003g / L, and the removal rate is greater than 85%; Mg 2+ The concentration is reduced to 0.002g / L~0.004g / L, and the removal rate is greater than 99.7%; Al 3+ The concentration is reduced to 0.0002g / L~0.0003g / L, and the removal rate is greater than 99.99%; Fe 3+ The concentration is reduced to trace amounts, with a removal rate of more than 99.99%. The main components of the tailings are slightly soluble substances such as calcium sulfate, calcium hydroxide, magnesium hydroxide, iron hydroxide, and calcium fluoride.

[0047] In the embodiment of the present invention, step (3) uses a calcium-containing neutralizing agent. After impurities are removed, the filtrate contains 0.6g / L to 0.9g / L of calcium ions. In step (4), the concentration of the carbonate solution added for deep calcium removal is 10% to 15%. After reacting for 1 to 2 hours, a plate and frame filter press is used for solid-liquid separation. The calcium ions are discarded as calcium carbonate. After deep calcium removal in step (4), the calcium ions are removed. 2+ The concentration is reduced to 0.002g / L~0.003g / L, and the calcium removal rate in this step is greater than 99.5%.

[0048] In the embodiment of the present invention, step (5) is to use 3kgf to 4kgf of steam to perform countercurrent heat exchange on the filtrate obtained in step (4) to evaporate ammonia. The NH4 + The ion concentration is reduced from 55g / L to 80g / L to 0.3g / L to 0.5g / L, and the recovery rate is greater than 99%; the mixed steam of ammonia gas and water vapor at the top of the liquid ammonia distillation tower is condensed in the top condenser to produce 13% to 18% ammonia water, which is reused as a stripping agent in the molybdenum stripping process.

[0049] In step (6) of the embodiment of the present invention, the ammonia water with a concentration of 13% to 18% obtained by absorption in the absorption tower in step (5) is combined with the mixed steam at the top of the tower after steam stripping and condensed in a condenser to recover ammonia, and the ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 External discharge.

[0050] In step (7) of the embodiment of the present invention, the water is cooled to 15°C to 20°C after heat exchange and then returned to the process water system for use.

[0051] Example 1

[0052] Taking the circulating water of the sulfuric acid system containing ammonia nitrogen in a primary molybdenum ore production enterprise as an example, the method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions provided by the present invention is used to recover ammonia nitrogen resources in the sulfuric acid precipitation mother liquor of the acid precipitation step in the process system, remove other impurity ions, and then return the treated water to the circulating water of the process system. The concentration of ammonia nitrogen and other impurity ions in the process water is effectively controlled. The specific steps are:

[0053] Step (1), using "6-9wt% trifatty amine or trioctylamine, 10-20wt% tributyl phosphate and 75-80wt% sulfonated kerosene mixture" extraction system to extract ammonium molybdate sulfuric acid precipitation mother liquor, the ammonium molybdate sulfuric acid precipitation mother liquor and the extractant two-phase flow ratio is A / O = 6: 1-10: 1, the extraction temperature is 25 ° C to 30 ° C, the mixing contact time is 3-5 minutes, 12.3g / L to 18.5g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the retained molybdenum concentration reaches 9g / L to 11g / L, the molybdenum concentration in the raffinate tail liquid is stably controlled at below 50mg / L, and raffinate water is obtained;

[0054] Step (2), the raffinate obtained in the above step (1) is subjected to oil separation for 1 h to 2 h, the organic phase is recovered to obtain an aqueous phase, and the aqueous phase is deoiled by an activated carbon absorption tower, i.e., ammonia recovery stock solution, and the oil content in the aqueous phase is 15 mg / L to 30 mg / L;

[0055] Step (3): the ammonia recovery solution obtained in step (2) is heated to 95 kg / m 3 ~110kg / m 3 Add lime (quicklime, slaked lime or carbide slag, the weight ratio is calculated based on the calcium oxide content) to neutralize the ammonia recovery raw liquid, adjust the pH value to 11.5-12.5, stir and react for 1 hour, then use a box filter press to filter to obtain the neutralized filtrate, and store the filter residue as tailings;

[0056] Step (4): the neutralized filtrate obtained in step (3) is treated with CO3 2-The soluble carbonate with a content of 8% to 12% is deeply decalcified to obtain a decalcified filtrate, and the filter residue is discarded and stored;

[0057] Step (5): The decalcified filtrate obtained in step (4) is subjected to countercurrent heat exchange with 3kgf to 3.5kgf of water vapor to evaporate ammonia. The bottom of the liquid ammonia evaporation tower is a purified liquid after deammoniation and impurity removal. The top of the liquid ammonia evaporation tower is a mixed steam of ammonia gas and water vapor. The mixed steam of ammonia gas and water vapor is condensed in a tower top condenser to produce 14% to 16% ammonia water, which is reused as a stripping agent in the molybdenum stripping process.

[0058] In step (6), the non-condensable gas generated by the top condenser after step (5), the steam generated during the neutralization process (3) and the process water are absorbed in the absorption tower, and the ammonia gas entrained in the non-condensable gas is recovered and concentrated to an ammonia concentration of 14% to 16% and then combined with the ammonia water in (5). The ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 Exclusion;

[0059] Step (7): heat exchange the purified liquid after deamination and impurity removal at the bottom of the tower (5) with the water phase after medium-depth oil removal in (2), cool it to 20°C to 25°C, and then return it to the process water system for use.

[0060] The process water obtained by the above process is returned to the leaching process, and NH4 is removed from the impurity water after neutralization and steam stripping to recover ammonia. + The ion concentration was reduced from 60g / L to 75g / L to 0.3g / L to 0.5g / L, and the ammonia nitrogen recovery rate was greater than 99.1%; SO4 2- Reduced from 185g / L to 210g / L to 0.9g / L to 1.2g / L, with a removal rate greater than 99.2%; Mg 2+ The concentration was reduced from 1.1g / L to 1.4g / L to 0.003g / L to 0.004g / L, and the removal rate was greater than 99.7%. 3+ The concentration was reduced from 1.8g / L to 2.3g / L to 0.0002g / L to 0.0003g / L, and the removal rate was greater than 99.99%; Fe 3+ The concentration was reduced from 0.4g / L to 0.7g / L to trace amounts, with a removal rate greater than 99.99%. Ammonia nitrogen was recovered and other anions and cations were removed before being returned to the production water, effectively controlling ammonia nitrogen and other anionic and cation impurities in the production water. After the production water was reused, the molybdenum leaching rate increased from 82% to over 91%, an increase of 9 percentage points. Simultaneously, due to the reduction in impurity ions in the leachate, the production of three-phase products during molybdenum stripping was reduced by 61.74%, and the loss of the organic phase was reduced by 43.24%, resulting in significant economic benefits.

[0061] Example 2

[0062] Taking the circulating water of the sulfuric acid system containing ammonia nitrogen produced by the acid leaching of a molybdenum concentrate as an example, the method for recovering ammonia nitrogen from the ammonium molybdate acid precipitation mother liquor and removing other impurity ions provided by the present invention is used to recover and reuse the ammonia nitrogen resources in the sulfuric acid precipitation mother liquor of the acid precipitation process in the process system, remove other impurity ions, and then return the treated water to the circulating water of the process system. The concentration of ammonia nitrogen and other impurity ions in the process water is effectively controlled. The specific steps are:

[0063] Step (1), using "6-9wt% trifatty amine or trioctylamine, 10-20wt% tributyl phosphate and 75-80wt% sulfonated kerosene mixture" extraction system to extract ammonium molybdate sulfuric acid precipitation mother liquor, the ammonium molybdate sulfuric acid precipitation mother liquor and the extractant two-phase flow ratio A / O = 6: 1-10: 1, the extraction temperature is 25 ° C to 30 ° C, the mixing contact time is 3-8 minutes, 9.5g / L to 17.5g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the retained molybdenum concentration reaches 10g / L to 11.5, the molybdenum concentration in the raffinate tail liquid is 15mg / L to 40mg / L, and raffinate water is obtained;

[0064] Step (2), separating the raffinate obtained in the above step (1) from oil, recovering the organic phase to obtain an aqueous phase, and removing oil from the aqueous phase through an activated carbon absorption tower, i.e., ammonia recovery stock solution, wherein the oil content in the aqueous phase is 10 mg / L to 23 mg / L;

[0065] Step (3): the ammonia recovery solution obtained in step (2) is heated to 90 kg / m 3 ~105kg / m 3 The ammonia recovery raw liquid is neutralized by adding lime (quicklime, slaked lime or carbide slag, the weight ratio of which is calculated based on the calcium oxide content), and the pH value is adjusted to 10.5-12. After stirring and reacting for 1 hour, the liquid is filtered using a box filter press to obtain a neutralized filtrate, and the filter residue is discarded and stored;

[0066] Step (4): the neutralized filtrate obtained in step (3) is treated with CO3 2- The soluble carbonate with a content of 8% to 12% is deeply decalcified to obtain a decalcified filtrate, and the filter residue is discarded and stored;

[0067] Step (5), the decalcified filtrate obtained in step (4) is subjected to countercurrent heat exchange with 2.5-3.5 kgf of steam to evaporate ammonia, and the bottom of the ammonia evaporation tower is a purified liquid after deammoniation and impurity removal; the top of the liquid ammonia evaporation tower is a mixed steam of ammonia gas and water vapor, and the mixed steam of ammonia gas and water vapor is condensed in a tower top condenser to produce 15%-16.5% ammonia water, which is reused as a stripping agent in the molybdenum stripping process;

[0068] In step (6), the non-condensable gas generated by the top condenser after step (5), the steam generated during the neutralization process (3) and the process water are absorbed in the absorption tower, and the ammonia gas entrained in the non-condensable gas is recovered and concentrated to 16.5% ammonia concentration and then combined with the ammonia water in (5). The ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 Exclusion;

[0069] Step (7): heat exchange the purified liquid after deamination and impurity removal at the bottom of the tower (5) with the water phase after medium-depth oil removal in (2), cool it to 20°C to 25°C, and then return it to the process water system for use.

[0070] The process water obtained by the above process is returned to the leaching process, and NH4 is removed from the impurity water after neutralization and steam stripping to remove ammonia. + The ion concentration was reduced from 50g / L to 70g / L to 0.4g / L to 0.6g / L, with a removal rate of more than 98.8%; SO4 2- Reduced from 195g / L to 220g / L to 0.6g / L to 1g / L, with a removal rate greater than 99.5%; Cu 2+ The concentration was reduced from 0.5g / L to 0.7g / L to trace amounts, with a removal rate of more than 99.99%; 2+ The concentration was reduced from 0.6g / L to 0.9g / L to 0.0005g / L to 0.0013g / L, and the removal rate was greater than 99.97%; 2+ The concentration was reduced from 1.5g / L to 2.1g / L to 0.002g / L to 0.003g / L, with a removal rate greater than 99.8%. After impurities were removed and returned to the production water, ammonia nitrogen and other impurity ions in the production water were effectively controlled. After the production water was reused, the molybdenum leaching rate increased from 85% to over 93%, an increase of 8 percentage points. Simultaneously, due to the reduction of impurity ions in the leachate, the production of three-phase products during molybdenum stripping was reduced by 52.55%, and the loss of the organic phase was reduced by 32.15%, resulting in significant economic benefits.

[0071] Example 3

[0072] The sulfuric acid system produced by acid leaching of a certain tungsten-molybdenum ore contains ammonia nitrogen in the circulating water of the process system. Figure 1 As shown, the present invention applies a method for recovering ammonia nitrogen and removing other impurity ions from ammonium molybdate acid precipitation mother liquor. The sulfuric acid precipitation mother liquor of the acid precipitation process in the process system is treated by the method for removing ammonia nitrogen and other impurity ions described in this patent. After treatment, the mother liquor is introduced into the circulating water of the process system. The ammonia nitrogen in the process water is recovered and reused, and the concentrations of other impurity ions are effectively controlled:

[0073] (1) The sulfuric acid precipitation mother liquor is extracted with an extraction system of a mixture of 6 to 9 wt% tri-fatty amine or trioctylamine, 10 to 20 wt% tributyl phosphate and 75 to 80 wt% sulfonated kerosene, the two-phase flow ratio of ammonium molybdate sulfuric acid precipitation mother liquor to the extractant is A / O=6:1 to 10:1, the extraction temperature is 25°C to 30°C, the mixing contact time is 3 to 8 minutes, 10.3 g / L to 19.7 g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the retained molybdenum concentration reaches 9 g / L to 11 g / L, and the molybdenum concentration in the raffinate tail liquid is 15 mg / L to 40 mg / L;

[0074] (2) separating the raffinate obtained in step (1) from oil, recovering the organic phase to obtain an aqueous phase, and removing oil from the aqueous phase through an activated carbon absorption tower, with the oil content being 8 mg / L to 20 mg / L;

[0075] (3) The ammonia recovery solution obtained in step (2) was heated at 120 kg / m 3 ~140kg / m 3 Add slaked lime to neutralize the recovered ammonia solution, adjust the pH value to 12-13, stir and react for 1.2 hours, then filter using a box filter press, and store the filter residue as tailings.

[0076] (4) The filtrate obtained in step (3) was treated with CO3 2- The soluble carbonate with a content of 8% to 12% is subjected to deep decalcification, and the filter residue is dumped;

[0077] (5) The filtrate obtained in step (4) is subjected to countercurrent heat exchange with 3.5-4.5 kgf of steam to evaporate ammonia, and the bottom of the ammonia evaporation tower is a purified liquid after deammoniation and impurity removal; the mixed steam of ammonia gas and water vapor at the top of the ammonia evaporation tower is condensed in a tower top condenser to produce 16%-18% ammonia water, which is reused as a stripping agent in the tungsten and molybdenum stripping process;

[0078] (6) The non-condensable gas generated by the top condenser after step (5), the steam generated in the neutralization process (3) and the process water are absorbed in the absorption tower, and the ammonia entrained in the non-condensable gas is recovered and concentrated to an ammonia concentration of 16% to 18% and then combined with the ammonia water in (5). The ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 Exclusion;

[0079] Step (7): heat exchange the purified liquid after deamination and impurity removal at the bottom of the tower (5) with the water phase after oil separation in the middle of (2), cool it to 20°C to 25°C, and then return it to the process water system for use.

[0080] The process water obtained by the above process is returned to the leaching process, and NH4 is removed from the impurity water after neutralization and steam stripping to remove ammonia. +The ion concentration was reduced from 45g / L to 65g / L to 0.35g / L to 0.55g / L, with a removal rate of more than 98.7%; SO4 2- The removal rate of Cu was reduced from 187g / L to 215g / L to 0.7g / L to 1.1g / L, and the removal rate was greater than 99.4%. 2+ The concentration was reduced from 0.8g / L to 1.3g / L to trace amounts, with a removal rate of more than 99.99%; 2+ The concentration was reduced from 0.7g / L to 1.5g / L to 0.0004g / L to 0.0011g / L, and the removal rate was greater than 99.99%; 2+ The concentration was reduced from 1.8g / L to 2.5g / L to 0.002g / L to 0.003g / L, with a removal rate greater than 99.9%. After impurities were removed and then returned to the production water, ammonia nitrogen and other impurity ions in the production water were effectively controlled. After the production water was reused, the molybdenum leaching rate increased from 85% to over 93%, an increase of 8 percentage points. At the same time, due to the reduction of impurity ions in the leachate, the production of three-phase products during stripping was reduced by 47.83%, and the loss of organic phase was reduced by 28.74%, resulting in significant economic benefits.

[0081] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Any content not described in detail in the present invention may be adapted from existing technologies.

Claims

1. A method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions, characterized in that: The method comprises the following steps: Step (1), extracting the ammonium molybdate sulfuric acid precipitation mother liquor using an extraction system of a mixture of 6-9 wt% trifatty amine or trioctylamine, 10-20 wt% tributyl phosphate, and 75-80 wt% sulfonated kerosene to obtain raffinate; Step (2), separating the raffinate from the oil, recovering the organic phase to obtain an aqueous phase, and removing the oil by deep adsorption on activated carbon to obtain ammonia recovery stock solution; Step (3), adding a neutralizing agent to the ammonia recovery stock solution, neutralizing and filtering to obtain a neutralized filtrate, and discarding the filter residue; Step (4), deep decalcifying the neutralized filtrate with carbonate to obtain a decalcified filtrate, and the filter residue is discarded and stored; Step (5) steam stripping the decalcified filtrate, the bottom of the liquid ammonia vapor tower is the purified liquid after deammoniation and impurity removal; the top of the liquid ammonia vapor tower is a mixed steam of ammonia and water vapor; the mixed steam at the top of the tower is condensed in a condenser to recover ammonia; Step (6), absorbing the non-condensable gas generated in the top condenser after steam stripping, the steam generated in the neutralization process and the process water in an absorption tower, and recovering the non-condensable gas and ammonia entrained in the neutralization steam; Step (7), heat exchange is performed on the purified liquid after deep impurity removal produced at the bottom of the tower after steam stripping and the ammonia recovery liquid after oil separation, and after cooling, the liquid is collected into the production system for reuse in the upstream process; The neutralizing agent added in step (3) is a calcium alkaline substance, and the calcium alkaline substance includes: CaO, Ca(OH)2, and carbide slag.

2. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: In the step (1), molybdenum resources are recovered from the ammonium molybdate sulfuric acid precipitation mother liquor, 8g / L to 20g / L of molybdenum resources are recovered from the sulfuric acid precipitation mother liquor, the molybdenum concentration in the raffinate tail liquid is ≤50mg / L, and the molybdenum resource recovery rate reaches more than 99.3%.

3. A method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, characterized in that: In the step (2), the raffinate water is subjected to oil separation and deep oil removal treatment by activated carbon adsorption, and the oil content in the aqueous phase obtained after the treatment is controlled to be ≤30 mg / L.

4. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: In the step (3), a neutralizing agent is added to the raffinate water to adjust the pH value to 11-13.

5. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: The amount of the neutralizer added in step (3) is based on the amount of Ca in the raffinate water. 2+ Mg 2+ 、Fe 3+ 、Al 3+ 、SO4 2- Concentration difference addition 70~130kg / m 3 Neutralizer, stirring time is 1 to 2 hours, and solid-liquid separation is performed using a plate and frame filter press.

6. The method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions according to claim 1, wherein: The concentration of the carbonate solution added for deep decalcification in step (4) is 10% to 15%. After reacting for 1 to 2 hours, solid-liquid separation is performed using a plate and frame filter press.

7. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: After deep decalcification in step (4), Ca 2+ The concentration is reduced to 0.002g / L~0.003g / L, and the calcium removal rate in this step is greater than 99.5%.

8. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: In the step (5), the mixed steam of ammonia gas and water vapor at the top of the liquid ammonia distillation tower is condensed in the tower top condenser to produce 13% to 18% ammonia water, which is reused as a stripping agent in the molybdenum stripping process.

9. The method for recovering ammonia nitrogen from ammonium molybdate acid precipitation mother liquor and removing other impurity ions according to claim 1, wherein: In the step (6), the ammonia water with a concentration of 13% to 18% obtained by absorption in the absorption tower in (5) is combined with the mixed steam at the top of the tower after steam stripping and condensed in a condenser to recover ammonia, and the ammonia nitrogen concentration discharged from the top of the absorption tower is less than 20 mg / m 3 .

10. The method for recovering ammonia nitrogen from ammonium molybdate precipitation mother liquor and removing other impurity ions according to claim 1, characterized in that: After heat exchange in step (7), the water is cooled to 15°C to 20°C and then returned to the process water system for use.

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