Ammonium molybdate washing wastewater treatment process

Abstract

The invention provides an ammonium molybdate washing wastewater treatment process. The ammonium molybdate washing wastewater treatment process comprises the following steps: S1, adding caustic soda liquid into washing wastewater, adjusting the pH value to 9-11, reacting for two hours, and preserving waste residues after coarse filtration, wherein the liquid is a sodium molybdate solution; finely filtering the sodium molybdate solution by adopting a precision filter, and reserving filtrate for later use; s2, adsorbing the filtrate through a resin bed, and preserving the liquid after adsorption; washing the resin bed with deionized water after adsorption; after the resin bed is washed, 5% ammonia water is used for resolving, and resolving liquid with the molybdenum content larger than or equal to 160 g / L is obtained; washing the resin bed with deionized water after desorption; and washing the resin bed, and regenerating with 3% hydrochloric acid. The ammonium molybdate washing wastewater treatment process provided by the invention has the advantages of high molybdenum recovery rate, low energy consumption, no secondary pollution, economy and environmental protection, and is suitable for wastewater treatment and resource demands of ammonium molybdate production enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a process for treating ammonium molybdate washing wastewater. Background Art

[0002] The wastewater generated by the ammonium molybdate washing process mainly contains Cu, Ca, Mg, Al, Fe, Si, Mo, SO42-, etc. The Mo content is 15 g / L, which needs to be recovered. In the prior art, when recycling the wastewater generated by the ammonium molybdate washing process, two methods are mostly used: lime precipitation method and evaporation method.

[0003] However, when using the lime precipitation method, molybdenum is recovered in the form of calcium molybdate precipitate, but the precipitate requires additional treatment (such as crushing and screening), the recovery rate is less than 80%, and the added value of calcium molybdate is low, and the economic efficiency is poor; and a large amount of heavy metal sludge (containing Cu, Fe, Al, etc.) is generated during the precipitation process. If it is not properly handled (such as solidification and landfill), it is easy to cause soil and groundwater pollution.

[0004] When using the evaporation method, evaporation and concentration consumes a lot of heat energy (energy consumption ≥ 3kW·h / m 3 ), the operating cost is high and it is not suitable for large-scale industrial application. In addition, long-term evaporation can easily cause the ammonium molybdate crystals to carry impurities, requiring frequent shutdown and cleaning, which reduces production efficiency.

[0005] Therefore, it is necessary to provide a new ammonium molybdate washing wastewater treatment process to solve the above technical problems. Summary of the invention

[0006] The technical problem solved by the present invention is to provide an ammonium molybdate washing wastewater treatment process which has high molybdenum recovery rate, low energy consumption, no secondary pollution, is both economical and environmentally friendly, and is suitable for wastewater treatment and resource utilization needs of ammonium molybdate production enterprises.

[0007] In order to solve the above technical problems, the ammonium molybdate washing wastewater treatment process provided by the present invention comprises the following steps:

[0008] S1: adding liquid alkali to the washing wastewater, adjusting the pH value to 9-11, reacting for two hours, and retaining the waste residue after coarse filtration, and the liquid is sodium molybdate solution; then finely filtering the sodium molybdate solution with a precision filter, and retaining the filtrate;

[0009] S2: The filtrate is adsorbed by the resin bed, and the adsorbed liquid is retained; the resin bed is washed with deionized water after adsorption; the resin bed is analyzed with 5% ammonia water after washing to obtain an analytical liquid containing molybdenum ≥ 160g / L; the resin bed is washed with deionized water after analysis; the resin bed is regenerated with 3% hydrochloric acid after washing; the regenerated resin bed is washed with deionized water; the adsorbed liquid is then passed through the resin bed for secondary adsorption, and the washing, analysis and regeneration of the resin bed are repeated after adsorption;

[0010] S3: The secondary adsorption liquid, washing water and hydrochloric acid regeneration water are mixed, filtered through a precision filter and then concentrated by membrane to obtain clean water and concentrated water;

[0011] S4: Recover the valuable water from the waste residue.

[0012] Preferably, in S1, a water ring vacuum pump is used for filtration, and a 600-mesh filter cloth is used for coarse filtration.

[0013] Preferably, the resin bed in S2 is a PY-01 type resin bed.

[0014] Preferably, in S3, the clean water is sent to a pure water treatment system, the concentrated water is evaporated by MVR to obtain by-product industrial salt, and the distilled water is reused.

[0015] Compared with the related art, the ammonium molybdate washing wastewater treatment process provided by the present invention has the following beneficial effects:

[0016] The present invention provides a process for treating ammonium molybdate washing wastewater, wherein the pH value is adjusted to 9-11, and sodium hydroxide is used to promote the Ca 2+ Mg 2+ , Fe 2+ / Fe 3+ 、Al 3+ 、SiO3 2- PO4 3- The formation of precipitation (removal rate ≥ 90%) significantly reduces the scaling risk of the subsequent membrane concentration system; D314 anion exchange resin is used for ion exchange, which is effective for MoO4 2- The adsorption capacity is 250g / L, the molybdenum content of the analytical solution is stable at ≥160g / L, and the recovery rate is ≥95%, far exceeding the existing technical level; the membrane concentration (water production rate 70%) combined with the MVR evaporation technology reduces the energy consumption by more than 40% compared with the traditional evaporation method, and the industrial salt by-product reaches the secondary product standard, realizing resource recycling; the precipitated slag contains valuable metals such as Cu and Fe, which can be recovered by hydrometallurgy; Cl in the analytical solution - It precipitates in the form of NH4Cl and completely decomposes after drying. ADM products contain no Cl. -residue; not affected by fluctuations in molybdenum content in wastewater (the main process can flexibly adjust the solid-liquid ratio), adapted to the characteristics of different molybdenum ore raw materials; the membrane concentration system intercepts impurities through precision filters (pore size ≤ 1μm) to ensure the quality of produced water (impurities <20ppm); the activity recovery rate of ion exchange resin after regeneration with 3% hydrochloric acid is ≥98%, and it can be recycled for more than 500 times; it can reduce sludge disposal costs and evaporation energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a flow chart of the ammonium molybdate washing wastewater treatment process. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0019] Please refer to Figure 1 ,in, Figure 1 The present invention provides a flow chart of the ammonium molybdate washing wastewater treatment process. The ammonium molybdate washing wastewater treatment process comprises the following steps:

[0020] S1: Impurity Removal:

[0021] Add liquid alkali (50%) to the washing wastewater, adjust the pH value to 9-11, react for two hours, filter with a water ring vacuum pump, use a 600-mesh filter cloth for coarse filtration, retain the residue after filtration, and the liquid is a sodium molybdate solution; then use a precision filter to finely filter the sodium molybdate solution, and retain the filtrate;

[0022] S1: Ion exchange process:

[0023] The filtrate is adsorbed by loading a PY-01 resin bed, and the adsorbed liquid is retained; the resin bed is washed with deionized water after adsorption; the resin bed is analyzed with 5% ammonia water after washing, and the analyzed liquid contains 160g / L molybdenum, and the impurity content of the analyzed liquid is low, and 0-grade ammonium dimolybdate can be produced; the resin bed is washed with deionized water after analysis; the resin bed is regenerated with 3% hydrochloric acid after washing; the regenerated resin bed is washed with deionized water; the adsorbed liquid is then passed through the resin bed for secondary adsorption, and the washing, analysis and regeneration of the resin bed are repeated after adsorption;

[0024] S1: Membrane Concentration:

[0025] The secondary adsorption liquid, washing water and hydrochloric acid regeneration water are mixed, filtered through a precision filter and concentrated by membrane, and the clean water is sent to the pure water treatment system. The concentrated water contains 6% sodium chloride, and the concentrated water is evaporated by MVR, and the distilled water is reused, and the by-product industrial salt reaches the second-grade product;

[0026] S1: Slag treatment:

[0027] The slag contains valuable metals such as copper and iron, which can be recovered.

[0028] Example:

[0029] 1) Impurity removal: Add sodium hydroxide, reagent A and reagent B to the washing wastewater, adjust the pH value to greater than 9, react for 2 hours, filter with a water ring vacuum pump, retain the residue, and test the liquid.

[0030] The first set of experimental results, the test results of the liquid after impurity removal are as follows:

[0031]

[0032] The first set of experimental results, the test results of the liquid after impurity removal are as follows:

[0033]

[0034] 2) Ion exchange system: After impurities are removed, the liquid enters the ion exchange system. The ion exchange column uses D314 anion exchange resin for adsorption. After adsorption saturation, 5% ammonia water is used for analysis, and then 3% hydrochloric acid is used to regenerate the resin. Molybdenum and ammonia water form ammonium molybdate solution, and the test report is as follows:

[0035] The first set of experimental results, the analytical solution test results are as follows:

[0036] Mo Cu K Fe Al Na Ca Mg SO42- PO43- g / L g / L g / L mg / L mg / L g / L mg / L mg / L g / L mg / L 88.92 0.0016 0.069 0.65 0.006 3.53 0.74 0.57

[0037] The first set of experimental results, the terminal column liquid detection results are as follows:

[0038]

[0039] The second set of experimental results, the analytical solution test results are as follows:

[0040]

[0041]

[0042] The second set of experimental results, the terminal column liquid detection results are as follows:

[0043]

[0044] Result analysis:

[0045] (1) The content of metal impurities in the terminal wastewater is less than 20 ppm, and it is not easy to clog during the membrane concentration process;

[0046] (2) During the impurity removal process, the removal rate of calcium and magnesium ions in the raw water reaches more than 90%. The total content of calcium and magnesium in the terminal water quality is 20ppm. The membrane concentration is calculated based on 70% water production, and the calcium and magnesium content in the concentrated water is 67ppm. Compared with the total calcium and magnesium content in tap water of 70ppm, the total calcium and magnesium content in the high salt water is 140ppm, and the scaling problem is small.

[0047] (3) According to the analysis results, the sulfate content is about 100 ppm, which is much lower than the solubility of calcium sulfate and has little effect on the subsequent membrane concentration;

[0048] (4) According to the analysis results, the phosphate content is about 3 ppm, which is much lower than the solubility of calcium phosphate and has little effect on the subsequent membrane concentration;

[0049] (5) During the impurity removal process, the removal rates of Cu and Fe are high, and the content in the terminal water quality is less than 1ppm, which has little impact on the subsequent membrane concentration;

[0050] (6) Due to the limitation of laboratory conditions, the content of Mo in the analytical solution is less than 150g / L, and the content of K impurities is high. According to the existing operating system of Zhongze Molybdenum, the content of Mo in the analytical solution can be stabilized at more than 160g / L, and K is less than 30ppm. Products with K≤60ppm can be produced. The results of Zhongze Molybdenum are as follows:

[0051] Group 1:

[0052] Mo K Na W CL- Al Cu g / L mg / L mg / L mg / L mg / L mg / L mg / L 162.94 16.88 4.27 21.32 4954.77 / /

[0053] Group 2:

[0054]

[0055]

[0056] (7) During the evaporation process, the saturated content of Cl ions in the analytical solution is about 30 g / L, and it precipitates in the form of ammonium chloride and completely decomposes during the drying process. The analysis shows that there is no Cl ion in the ADM.

[0057] (8) During the ion exchange process, it is not affected by the molybdenum content in the wastewater, which is beneficial to the main process of ammonium molybdate. The main process can adjust the solid-liquid ratio according to the raw materials to improve the adaptability of the main process to the raw materials.

[0058] Compared with the related art, the ammonium molybdate washing wastewater treatment process provided by the present invention has the following beneficial effects:

[0059] The present invention provides a process for treating ammonium molybdate washing wastewater, wherein the pH value is adjusted to 9-11, and sodium hydroxide is used to promote the Ca 2+ Mg 2+ , Fe 2+ / Fe 3+ 、Al3+ 、SiO3 2- PO4 3- The formation of precipitation (removal rate ≥ 90%) significantly reduces the scaling risk of the subsequent membrane concentration system; D314 anion exchange resin is used for ion exchange, which is effective for MoO4 2- The adsorption capacity is 250g / L, the molybdenum content of the analytical solution is stable at ≥160g / L, and the recovery rate is ≥95%, far exceeding the existing technical level; the membrane concentration (water production rate 70%) combined with the MVR evaporation technology reduces the energy consumption by more than 40% compared with the traditional evaporation method, and the industrial salt by-product reaches the secondary product standard, realizing resource recycling; the precipitated slag contains valuable metals such as Cu and Fe, which can be recovered by hydrometallurgy; Cl in the analytical solution - It precipitates in the form of NH4Cl and completely decomposes after drying. ADM products contain no Cl. - residue; not affected by fluctuations in molybdenum content in wastewater (the main process can flexibly adjust the solid-liquid ratio), adapted to the characteristics of different molybdenum ore raw materials; the membrane concentration system intercepts impurities through precision filters (pore size ≤ 1μm) to ensure the quality of produced water (impurities <20ppm); the activity recovery rate of ion exchange resin after regeneration with 3% hydrochloric acid is ≥98%, and it can be recycled for more than 500 times; it can reduce sludge disposal costs and evaporation energy consumption.

[0060] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A process for treating ammonium molybdate washing wastewater, characterized in that: The following steps are involved: S1: adding liquid alkali to the washing wastewater, adjusting the pH value to 9-11, reacting for two hours, and retaining the waste residue after coarse filtration, and the liquid is sodium molybdate solution; then finely filtering the sodium molybdate solution with a precision filter, and retaining the filtrate; S2: The filtrate is adsorbed by the resin bed, and the liquid is retained after adsorption; the resin bed is washed with deionized water after adsorption; After washing the resin bed, the resin bed is analyzed with 5% ammonia water to obtain an analysis solution containing molybdenum ≥ 160 g / L; after analysis, the resin bed is washed with deionized water; After washing the resin bed, regenerate it with 3% hydrochloric acid; The regenerated resin bed is washed with deionized water; The adsorbed liquid is then passed through the resin bed for secondary adsorption, and after adsorption, the resin bed is washed, analyzed and regenerated repeatedly; S3: The secondary adsorption liquid, washing water and hydrochloric acid regeneration water are mixed, filtered through a precision filter and then concentrated by membrane to obtain clean water and concentrated water; S4: Recover the valuable water from the waste residue.

2. The ammonium molybdate washing wastewater treatment process according to claim 1, characterized in that: In S1, a water ring vacuum pump is used for filtration, and a 600-mesh filter cloth is used for coarse filtration.

3. The ammonium molybdate washing wastewater treatment process according to claim 1, characterized in that: The resin bed in S2 is a PY-01 type resin bed.

4. The ammonium molybdate washing wastewater treatment process according to claim 1, characterized in that: In S3, the clean water is sent to the pure water treatment system, and the concentrated water is evaporated by MVR to obtain by-product industrial salt, and the distilled water is reused.

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