Method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag

Abstract

The invention belongs to the technical field of inorganic chemical industry, and discloses a method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag. The purity of the vanadium pentoxide product prepared by the method can meet the use requirements in the fields of chemical raw materials, vanadium redox flow batteries, lithium battery electrode materials, catalysts and the like; the prepared calcium phosphate can be applied to biomedical materials, food and nutritional supplement additives, coatings, catalyst carriers, phosphate fertilizers and the like. According to the method, the high-phosphorus vanadium slag is treated through calcification roasting and CO2-assisted leaching, the energy consumption is reduced by utilizing an auxiliary agent, and effective separation of V and P is realized through leaching of a sodium carbonate solution. Calcium carbonate obtained after impurity removal can be recycled, leaching residues are converted into high-grade calcium phosphate, and waste liquid is circularly used for impurity removal. The process is green and environment-friendly, low in energy consumption, low in cost and easy to control, the recovery rate of vanadium exceeds 80%, and the purity of vanadium pentoxide and the purity of calcium phosphate can reach 99.5% or above and 99% or above respectively.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic chemical industry and relates to a method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag. Background Art

[0002] High-phosphorus vanadium slag is vanadium-containing waste slag produced during steel smelting and vanadium extraction from vanadium-titanium magnetite. It also includes vanadium-containing substances such as deactivated vanadium-phosphorus oxygen catalysts and vanadium-phosphorus co-existing ore tailings. Direct disposal or storage will not only cause waste of vanadium and phosphorus resources, but also cause environmental pollution. Extracting vanadium and phosphorus from high-phosphorus vanadium slag has always attracted the interest of researchers. The main process technologies currently include roasting-leaching vanadium extraction, sub-molten salt method vanadium extraction, solvent extraction vanadium extraction, ion exchange method vanadium extraction, etc. However, most of the process processes have problems such as high energy consumption, complex subsequent treatment processes, and difficulty in producing high-purity products. Among them, the traditional sodium roasting technology is to mix sodium salt with high-phosphorus vanadium slag and calcine it at high temperature to produce sodium vanadate and sodium phosphate, and then water leaching, impurity removal, and vanadium precipitation to prepare vanadium products. This process method consumes a lot of sodium salt, and the roasting process will produce Cl 2 The wastewater contains high salt content and high treatment cost. In addition, phosphorus and vanadium are easy to form vanadium phosphate (such as VOPO 4 ), which is difficult to remove effectively, affecting the vanadium recovery rate and the purity of vanadium products.

[0003] China CN202111441672.2 discloses a method for preparing vanadium pentoxide using high-phosphorus and high-calcium vanadium slag and recycling the leaching solution. The high-phosphorus and high-calcium vanadium slag and the low-phosphorus and low-calcium vanadium slag are mixed and ground to obtain a mixed vanadium slag, which is roasted and ground, then added to the leaching mother liquor, a phosphorus inhibitor is added, leached, filtered and washed to obtain a vanadium-containing leaching solution, and ammonium salt is added to precipitate vanadium and calcine to obtain vanadium pentoxide. Chinese patent CN110643838A discloses a method of roasting vanadium slag with calcium sulfate, wherein the vanadium slag is mixed with calcium sulfate and then roasted, the roasted clinker is crushed and placed in an acid solution for leaching, and the solid-liquid separation obtains a leachate. Although this process achieves a high vanadium extraction efficiency, the roasting temperature is too high; Chinese patent CN112176205B discloses a method of extracting vanadium from vanadium-phosphorus-containing solid waste, wherein the solid waste is first roasted at 500-600°C, then heated and stirred with a strong alkaline solution for leaching, and then aluminum salt is added to the leachate for precipitation, and solid-liquid separation obtains a vanadium-containing purified liquid. Although this process reduces the roasting temperature and energy consumption, the waste slag is not treated, the alkali consumption is large, and the process is incomplete. Chinese patent CN112266017B discloses a method for preparing sodium vanadate from solid waste containing vanadium and phosphorus, which includes crushing the solid waste containing vanadium and phosphorus, adding it to a sodium hydroxide solution and introducing an oxidizing gas for oxidation, adding a precipitant to separate vanadium and phosphorus, and then cooling and crystallizing the purified vanadium-containing solution to obtain sodium vanadate. This method abandons the roasting step and directly uses alkaline leaching, but the consumption of alkali and oxygen is large, the process takes a long time, and a large amount of wastewater is generated, and the product purity is not high.

[0004] The currently used process methods have their own characteristics, but they have failed to achieve deep separation of vanadium and phosphorus, and it is difficult to simultaneously achieve high recovery rate (>90%) and high purity (>99%) preparation of vanadium and phosphorus elements. It is urgent to develop a new process for efficient, green, and low-cost recovery of high-phosphorus vanadium slag to achieve efficient separation and high-value utilization of vanadium and phosphorus. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag. The purity of the prepared vanadium pentoxide product can meet the requirements of chemical raw materials, vanadium flow batteries, lithium battery electrode materials, catalysts and other fields; the prepared calcium phosphate can be used in biomedical materials, food and nutritional supplements, coatings, catalyst carriers, phosphate fertilizers, etc.

[0006] The technical solution of the present invention:

[0007] A method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag, comprising the following steps:

[0008] Step 1: Mix high phosphorus vanadium slag, calcifying agent and additives in proportion, ball mill or air flow crush, roast and cool to room temperature;

[0009] Step 2: stirring and mixing the roasted product obtained in step 1 with the leaching agent solution, introducing carbon dioxide gas, leaching at a certain temperature for a certain time, and then filtering to obtain a leaching filtrate and a filter residue;

[0010] Step 3: adding a certain amount of precipitant to the leaching filtrate obtained in step 2, filtering to obtain a purified liquid and a precipitate after the reaction is complete; the obtained precipitate is returned to step 1 for recycling as a calcifying agent;

[0011] Step 4: adding a certain amount of ammonium salt to the purified solution obtained in step 3, adjusting the pH of the solution, heating and stirring for a period of time, and filtering to obtain a filtrate and ammonium metavanadate solid;

[0012] Step 5: washing, drying and calcining the ammonium metavanadate solid obtained in step 4 to obtain high-purity vanadium pentoxide;

[0013] Step 6: Add the filter residue obtained in step 2 to the acid solution, stir and leach, adjust the pH, filter and wash after the reaction is complete, and obtain calcium phosphate; the filtrate can be returned to step 3 and mixed with the leaching filtrate for recycling.

[0014] The high-phosphorus vanadium slag in step 1 is one of vanadium-titanium magnetite waste slag, deactivated vanadium-phosphorus-oxygen catalyst, and vanadium-phosphorus symbiotic ore tailings;

[0015] The calcifying agent in step 1 is one of calcium oxide, calcium carbonate and calcium hydroxide;

[0016] The auxiliary agent in step 1 is one of calcium fluoride and calcium oxide;

[0017] The mass ratio of the high-phosphorus vanadium slag to the calcifying agent in step 1 is 1:0.5 to 1:3; the mass ratio of the auxiliary agent to the high-phosphorus vanadium slag is 1:500 to 1:5000; the calcination temperature is 500 to 1000° C., and the calcination time is 30 to 240 min;

[0018] The leaching agent solution used in step 2 is one of a sodium carbonate aqueous solution and a sodium bicarbonate aqueous solution, and the concentration is 100-180 g / L;

[0019] In step 2, the amount of leaching agent solution required for leaching the roasted product is 2-20 mL / g; the leaching temperature is 25-90° C., and the leaching time is 10-90 min;

[0020] In step 2, CO is introduced 2 The gas flow rate is 50-200 mL / min;

[0021] The precipitant used in step 3 is one of calcium chloride, calcium sulfate, and calcium hydrogen sulfate; the amount of the precipitant is n(Ca 2 + ):n(CO3 2- ) is 0.8-1.0, and the reaction time is 5-100min;

[0022] The ammonium salt used in step 4 is one of ammonium chloride and ammonium sulfate, the amount of the ammonium salt is 0.1-0.5 g / mL, the pH is adjusted to 6-9, the reaction temperature is 20-60° C., and the reaction is carried out for 10-90 min;

[0023] The washing liquid used in step 5 is deionized water, the washing water dosage is 10-60 mL / g, the drying temperature is 40-80° C., the drying time is 5-12 h, the calcination temperature is 550° C., and the calcination time is 90-180 min;

[0024] The acid solution used in step 6 is a 1-5 mol / L hydrochloric acid solution, and the amount used is 2-10 mL / g;

[0025] In step 6, the pH adjusting agent is a NaOH aqueous solution with a concentration of 10 mol / L, and the pH is adjusted to 2-5.5.

[0026] The beneficial effects of the present invention are: through calcination roasting and CO 2 Auxiliary leaching is used to treat high-phosphorus vanadium slag, and auxiliary agents are used to reduce energy consumption. Sodium carbonate solution is used to leach and effectively separate V and P. The calcium carbonate obtained by impurity removal can be reused, the leached slag is converted into high-grade calcium phosphate, and the waste liquid is recycled for impurity removal. The process is green and environmentally friendly, with low energy consumption, low cost and easy control. The vanadium recovery rate exceeds 80%, and the purity of vanadium pentoxide and calcium phosphate can reach 99.5% and above 99% respectively. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is described in detail below in conjunction with the technical solution.

[0028] Example 1

[0029] 100 g of high-phosphorus vanadium slag and 70 g of calcium oxide were mixed and ball-milled, and 10 g of calcium fluoride was added as an auxiliary agent for calcination. The mixture was calcined at 900 °C for 120 min and then cooled to room temperature. The calcined product was placed in 750 mL of 140 g / L sodium carbonate solution and CO was introduced at 80 °C at a rate of 120 mL / min. 2Auxiliary dissolution and leaching for 60 minutes, then filtering to obtain a filtrate and a filter residue; wherein the extraction rates of V and P are 82.74% and 1.49% respectively; 109g of calcium chloride is added to the obtained filtrate, react for 30 minutes, and then filtered to obtain a purified liquid and a precipitate; wherein the removal rate of carbonate ions is 99.74%; the obtained calcium carbonate is reused for calcium roasting; 90g of ammonium chloride is added to the obtained purified liquid, and the solution pH is adjusted to 8 with sodium hydroxide solution, heated and stirred at 50°C for 60 minutes, and directly filtered to obtain a filtrate and ammonium metavanadate solid; the vanadium precipitation rate is 99.21%; the obtained ammonium metavanadate solid is washed with 500mL of deionized water and dried at 60°C for 12h to obtain ammonium metavanadate; then the ammonium metavanadate is calcined at 550°C for 120min to obtain vanadium pentoxide. The obtained leached residue was added into 450 mL of 3 mol / L hydrochloric acid solution, and the mixture was stirred for dissolution and leaching for 20 min. The pH value was adjusted to 4. After the reaction was complete, the mixture was filtered and washed to obtain calcium phosphate. The filtrate obtained by filtration was reused for the removal of carbonate.

[0030] According to the national standard YB / T 4218-2010 ammonium persulfate oxidation-ammonium ferrous sulfate titration method, the vanadium pentoxide product content is 99.53%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including impurities Na 0.021%, Al 0.012%, P 0.009%, Si 0.034%, Ca 0.012. The calcium phosphate content is 99.04%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including Fe 0.031%, V 0.747%, Si 0.012%, Al 0.024%.

[0031] Example 2

[0032] 100 g of high-phosphorus vanadium slag and 134 g of calcium carbonate were mixed and ball-milled, and 8 g of calcium fluoride was added as an auxiliary agent for calcination. The mixture was calcined at 850 °C for 150 min and then cooled to room temperature. The calcined product was placed in 800 mL of 130 g / L sodium carbonate solution and CO was introduced at 90 °C at 150 mL / min. 2Auxiliary dissolution and leaching for 40 minutes, then filtering to obtain a filtrate and a filter residue; wherein the extraction rates of V and P are 83.64% and 1.33% respectively; 100g of calcium chloride is added to the obtained filtrate, react for 30 minutes, and then filtered to obtain a purified liquid and a precipitate; wherein the removal rate of carbonate ions is 99.68%; the obtained calcium carbonate is reused for calcium roasting; 85g of ammonium chloride is added to the obtained purified liquid, and the solution pH is adjusted to 9 with sodium hydroxide solution, heated and stirred at 40°C for 80 minutes, and directly filtered to obtain a filtrate and ammonium metavanadate solid; the vanadium precipitation rate is 99.19%; the obtained ammonium metavanadate solid is washed with 550mL of deionized water and dried at 60°C for 14h to obtain ammonium metavanadate; then the ammonium metavanadate is calcined at 550°C for 120min to obtain vanadium pentoxide. The obtained leached residue was added into 500 mL of 2 mol / L hydrochloric acid solution, and the solution was dissolved and leached for 30 min under stirring, and the pH was adjusted to 3.5. After the reaction was complete, the solution was filtered and washed to obtain calcium phosphate. The filtrate obtained by filtration was reused for the removal of carbonate.

[0033] According to the national standard YB / T 4218-2010 ammonium persulfate oxidation-ammonium ferrous sulfate titration method, the vanadium pentoxide product content is 99.51%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), wherein the impurities are Na 0.02%, Al 0.011%, P 0.011%, Si 0.031%, and Ca 0.011. The calcium phosphate content is 99.01%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), wherein the impurities are Fe 0.032%, V 0.744%, Si 0.011%, and Al 0.026%.

[0034] Example 3

[0035] 100 g of high-phosphorus vanadium slag was mixed with 80 g of calcium oxide and ball-milled, and then 9 g of calcium fluoride was added as an auxiliary agent for calcination. The mixture was calcined at 880 °C for 150 min and then cooled to room temperature. The calcined product was placed in 800 mL of 160 g / L sodium carbonate solution and CO was introduced at 70 °C at a rate of 180 mL / min. 2Auxiliary dissolution and leaching for 30 minutes, then filtering to obtain a filtrate and a filter residue; wherein the extraction rates of V and P are 84.16% and 1.61% respectively; 120g of calcium chloride is added to the obtained filtrate, react for 40 minutes, and then filtered to obtain a purified liquid and a precipitate; wherein the removal rate of carbonate ions is 99.83%; the obtained calcium carbonate is reused for calcium roasting; 100g of ammonium chloride is added to the obtained purified liquid, and the solution pH is adjusted to 8 with sodium hydroxide solution, heated and stirred at 40°C for 40 minutes, and directly filtered to obtain a filtrate and ammonium metavanadate solid; the vanadium precipitation rate is 99.33%; the obtained ammonium metavanadate solid is washed with 600mL of deionized water and dried at 50°C for 12h to obtain ammonium metavanadate; then the ammonium metavanadate is calcined at 500°C for 120min to obtain vanadium pentoxide. The obtained leached residue was added into 500 mL of 3 mol / L hydrochloric acid solution, stirred and dissolved for 15 min, the pH was adjusted to 4, and after the reaction was complete, it was filtered and washed to obtain calcium phosphate; the filtrate obtained by filtration was reused for the removal of carbonate ions.

[0036] According to the national standard YB / T 4218-2010 ammonium persulfate oxidation-ammonium ferrous sulfate titration method, the vanadium pentoxide product content is 99.59%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including impurities Na 0.019%, Al 0.011%, P 0.008%, Si 0.031%, Ca 0.011. The calcium phosphate content is 99.09%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including Fe 0.029%, V 0.743%, Si 0.012%, Al 0.025%.

[0037] Example 4

[0038] 100 g of high-phosphorus vanadium slag was mixed with 106 g of calcium hydroxide and ball-milled, and 8 g of calcium fluoride was added as an auxiliary agent for calcination. The mixture was calcined at 900 °C for 180 min and then cooled to room temperature. The calcined product was placed in 700 mL of 160 g / L sodium carbonate solution and CO was introduced at 60 °C at 140 mL / min. 2Auxiliary dissolution and leaching for 90 minutes, then filtering to obtain a filtrate and a filter residue; wherein the extraction rates of V and P are 83.87% and 1.53% respectively; 110g of calcium chloride is added to the obtained filtrate, react for 40 minutes, and then filtered to obtain a purified liquid and a precipitate; wherein the removal rate of carbonate ions is 99.79%; the obtained calcium carbonate is reused for calcium roasting; 80g of ammonium chloride is added to the obtained purified liquid, and the solution pH is adjusted to 8.5 with sodium hydroxide solution, heated and stirred at 60°C for 90 minutes, and directly filtered to obtain a filtrate and ammonium metavanadate solid; the vanadium precipitation rate is 99.17%; the obtained ammonium metavanadate solid is washed with 450mL of deionized water and dried at 60°C for 15h to obtain ammonium metavanadate; then the ammonium metavanadate is calcined at 550°C for 120min to obtain vanadium pentoxide. The obtained leached residue was added into 400 mL of 4 mol / L hydrochloric acid solution, and the solution was dissolved and leached for 30 min under stirring, and the pH was adjusted to 4.5. After the reaction was complete, the solution was filtered and washed to obtain calcium phosphate. The filtrate obtained by filtration was reused for the removal of carbonate.

[0039] According to the national standard YB / T 4218-2010 ammonium persulfate oxidation-ammonium ferrous sulfate titration method, the vanadium pentoxide product content is 99.61%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including impurities Na 0.017%, Al 0.011%, P 0.008%, Si 0.029%, Ca 0.011. The calcium phosphate content is 99.07%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including Fe 0.03%, V 0.742%, Si 0.012%, Al 0.026%.

[0040] Example 5

[0041] 100 g of high-phosphorus vanadium slag and 90 g of calcium oxide were mixed and ball-milled, and 11 g of calcium fluoride was added as an auxiliary agent for calcination. The mixture was calcined at 860 °C for 160 min and then cooled to room temperature. The calcined product was placed in 800 mL of 160 g / L sodium carbonate solution and CO was introduced at 80 °C at a rate of 160 mL / min. 2Auxiliary dissolution and leaching for 90 minutes, then filtering to obtain a filtrate and a filter residue; wherein the extraction rates of V and P are 84.13% and 1.79% respectively; 110g of calcium chloride is added to the obtained filtrate, react for 40 minutes, and then filtered to obtain a purified liquid and a precipitate; wherein the removal rate of carbonate ions is 99.73%; the obtained calcium carbonate is reused for calcium roasting; 100g of ammonium chloride is added to the obtained purified liquid, and the solution pH is adjusted to 9 with sodium hydroxide solution, heated and stirred at 40°C for 30 minutes, and directly filtered to obtain a filtrate and ammonium metavanadate solid; the vanadium precipitation rate is 99.27%; the obtained ammonium metavanadate solid is washed with 600mL of deionized water and dried at 60°C for 12h to obtain ammonium metavanadate; then the ammonium metavanadate is calcined at 550°C for 120min to obtain vanadium pentoxide. The obtained leached residue was added into 500 mL of 4 mol / L hydrochloric acid solution, and the solution was dissolved and leached for 15 min under stirring, and the pH was adjusted to 3.5. After the reaction was complete, the solution was filtered and washed to obtain calcium phosphate. The filtrate obtained by filtration was reused for the removal of carbonate ions.

[0042] According to the national standard YB / T 4218-2010 ammonium persulfate oxidation-ammonium ferrous sulfate titration method, the vanadium pentoxide product content is 99.57%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including impurities Na 0.022%, Al 0.011%, P 0.009%, Si 0.031%, Ca 0.013. The calcium phosphate content is 99.06%, and the impurity content is determined by inductively coupled plasma emission spectrometer (ICP), including Fe 0.028%, V 0.754%, Si 0.011%, Al 0.023%.

Claims

1. A method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag, characterized in that: Here are the steps: Step 1: Mix high phosphorus vanadium slag, calcifying agent and additives in proportion, ball mill or air flow crush, roast and cool to room temperature; Step 2: stirring and mixing the roasted product obtained in step 1 with the leaching agent solution, introducing carbon dioxide gas, leaching at a certain temperature for a certain time, and then filtering to obtain a leaching filtrate and a filter residue; Step 3: adding a certain amount of precipitant to the leaching filtrate obtained in step 2, filtering to obtain a purified liquid and a precipitate after the reaction is complete; the obtained precipitate is returned to step 1 for recycling as a calcifying agent; Step 4: adding a certain amount of ammonium salt to the purified solution obtained in step 3, adjusting the pH of the solution, heating and stirring for a period of time, and filtering to obtain a filtrate and ammonium metavanadate solid; Step 5: washing, drying and calcining the ammonium metavanadate solid obtained in step 4 to obtain high-purity vanadium pentoxide; Step 6: adding the filter residue obtained in step 2 to an acid solution, stirring and leaching, adjusting the pH, filtering and washing after the reaction is complete, to obtain calcium phosphate; The filtrate can be returned to step 3 and mixed with the leaching filtrate for recycling.

2. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 1, The high-phosphorus vanadium slag is one of vanadium-titanium magnetite waste slag, deactivated vanadium-phosphorus-oxygen catalyst, and vanadium-phosphorus paragenesis ore tailings; The calcifying agent is one of calcium oxide, calcium carbonate and calcium hydroxide; The auxiliary agent is one of calcium fluoride and calcium oxide; The mass ratio of high phosphorus vanadium slag to calcifier is 1:0.5 to 1:3; The mass ratio of the additive to the high phosphorus vanadium slag is 1:500 to 1:5000; The calcination temperature is 500-1000°C, and the calcination time is 30-240 minutes.

3. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 2, The leaching agent solution used is one of a sodium carbonate aqueous solution and a sodium bicarbonate aqueous solution, and the concentration of the leaching agent solution is 100-180 g / L; The amount of leaching agent solution required for leaching the roasted product is 2-20 mL / g; the leaching temperature is 25-90° C., and the leaching time is 10-90 min; The flow rate of CO2 gas is 50-200 mL / min.

4. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 3, The precipitant used is one of calcium chloride, calcium sulfate and calcium hydrogen sulfate; The amount of precipitant is n(Ca 2+ ):n(CO3 2- ) is 0.8-1.0, and the reaction time is 5-100min.

5. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 4, The ammonium salt used is one of ammonium chloride and ammonium sulfate, the amount of ammonium salt used is 0.1-0.5 g / mL, and the pH is adjusted to 6-9; The reaction temperature is 20-60°C and the reaction time is 10-90 minutes.

6. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 5, The washing liquid used is deionized water, and the amount of washing water used is 10-60 mL / g; The drying temperature is 40-80°C and the drying time is 5-12h; The calcination temperature is 550°C and the calcination time is 90 to 180 minutes.

7. The method for preparing vanadium pentoxide and calcium phosphate from high-phosphorus vanadium slag according to claim 1, characterized in that: In step 6, The acid solution used is a 1-5 mol / L hydrochloric acid solution, and the dosage is 2-10 mL / g; The pH adjuster is a NaOH aqueous solution with a concentration of 10 mol / L, which is used to adjust the pH to 2-5.5.