Vanadium-containing steel slag vanadium-iron comprehensive recovery method

Abstract

The application discloses a kind of vanadium-containing steel slag vanadium-iron comprehensive recovery method, belong to vanadium-containing secondary resource clean vanadium extraction technical field, solve the low recovery rate of vanadium extraction in prior art vanadium-containing steel slag, calcium cannot be effectively utilized or acid consumption is large, environmental unfriendly problem.It includes: vanadium-containing steel slag is low-temperature calcined with ammonium sulfate;Ammonia-containing tail gas is obtained by water absorption to obtain ammonia water solution;After roasting clinker is cooled, first leaching, filtration is obtained first leaching solution and first leaching residue;Vanadium-iron co-precipitation is carried out by adjusting the pH value of first leaching solution with ammonia water solution;The mixture of yellow ammonium jarosite and ammonium polyvanadate is secondly leached with ammonium salt (or ammonia water);Second leaching solution is cooled and crystallized to obtain ammonium metavanadate and vanadium precipitation mother liquor;Ammonia water and carbon dioxide or ammonium carbonate are added to first leaching residue to carry out mineralization and carbon sequestration;Mineralization mother liquor of step 7 and first mother liquor of step 4 are evaporated and crystallized to obtain ammonium sulfate.The method of the application can realize the comprehensive utilization of vanadium-iron-calcium in vanadium-containing solid waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clean vanadium extraction from vanadium-containing secondary resources, and particularly relates to a method for comprehensive recovery of vanadium and iron from vanadium-containing steel slag. BACKGROUND

[0002] Vanadium is a strategic and critical metal, which has been listed in the key mineral list by developed countries such as Europe and the United States. China is the country with the richest vanadium resources in the world, and also the country with the highest vanadium production. Vanadium slag is the main raw material for vanadium extraction in China, accounting for more than 88% of the vanadium production capacity in China. Vanadium is mainly used in the fields of steel, titanium alloy, chemical industry and energy storage, and the application of vanadium in the steel field accounts for more than 91% in China, while the application in the energy storage field is less than 5%. With the increasing demand for vanadium in non-steel fields such as vanadium-based energy storage materials and bismuth vanadate chemical materials, and the restriction of steel production capacity on vanadium slag production capacity, the clean and efficient utilization of vanadium-containing steel slag, stone coal and other secondary and low-grade vanadium resources has attracted more and more attention.

[0003] Vanadium-containing steel slag is produced in the steelmaking process of vanadium-iron melt from vanadium-titanium magnetite production. Although the vanadium content (1% to 5%) is lower than that of vanadium slag (10% to 25%), it is much higher than that in stone coal (0.13% to 1.2%), and it is a valuable vanadium-containing secondary resource. Vanadium-containing steel slag is a byproduct of blast furnace-converter smelting with vanadium-titanium magnetite as raw material. The source of vanadium-containing steel slag is divided into two types: one is the residual vanadium in semi-steel entering the slag through converter steelmaking, and the other is the vanadium-containing molten iron directly smelted without vanadium slag blowing. The annual discharge of steel enterprises in China is millions of tons, and most of the vanadium-containing steel slag has not been effectively utilized except for a small part returned to sintering. Therefore, the extraction of valuable metal vanadium from vanadium-containing steel slag is of great significance to promote the development of vanadium industry and the comprehensive utilization of secondary resources in China.

[0004] The main methods for vanadium extraction from vanadium-containing steel slag at home and abroad are pyrometallurgical smelting and hydrometallurgical smelting. Pyrometallurgical smelting for vanadium extraction mainly smelts high-grade vanadium slag by ore blending, and hydrometallurgical vanadium extraction mainly includes sodium roasting method, direct leaching method, etc. Steel slag returning method is the main method for pyrometallurgical smelting of vanadium-containing steel slag. This method puts vanadium-containing steel slag into blast furnace as a flux with sinter. Vanadium-containing phase is converted into vanadium element through reduction smelting to produce high vanadium iron melt containing 3% to 10% vanadium, and then high-grade vanadium pentoxide with a grade of 46% is obtained by blowing to obtain vanadium pentoxide or vanadium-iron alloy. It is found that with the increase of 1% of sinter slag ratio, the TFe of sinter is reduced by about 0.116%, the phosphorus content is increased by about 0.005%, and the phosphorus content in molten iron is increased by about 0.006%. As can be seen, although the steel slag returning method can recover vanadium, the impurity phosphorus is easily enriched in molten iron, which increases the burden of dephosphorization in steelmaking process. The low content of active calcium oxide in vanadium-containing steel slag will reduce the grade of sinter, increase the amount of slag and energy consumption in the ironmaking process, and it is not suitable to be added in large quantities.

[0005] The roasting technology of sodium oxidation and calciumization for extracting vanadium is mature, but there are various problems. However, the calcium content of vanadium-containing steel slag is as high as 40%, and in order to improve the extraction rate of vanadium, a high amount of sodium salt needs to be added. During the roasting process, calcium silicate is wrapped and decomposed, and sodium silicate glass phase with low melting point is easily generated. The melting of the new wrapped phase will hinder the generation of sodium vanadate, thereby reducing the conversion rate of vanadium. In order to eliminate the influence of calcium vanadate insoluble in the sodium roasting leaching process, researchers use the method of sodium roasting-sodium carbonate leaching to improve the leaching rate of vanadium. However, this technology has the problems of high consumption of sodium salt, low extraction rate of vanadium, and the tailings containing sodium salt cannot be utilized. In addition, for the field of hydrometallurgy of vanadium-containing steel slag, researchers have also proposed technologies such as calciumization roasting-ammonium carbonate leaching and calcium reduction roasting-water leaching, but these technologies all regard calcium as a harmful resource and do not consider the comprehensive extraction of vanadium and calcium.

[0006] CN114150165A proposes a method for enriching vanadium from vanadium-containing steel slag while preparing nano calcium carbonate. This technology realizes the enrichment of vanadium in vanadium-containing steel slag through acid dissolution reaction, while impurities enter the acid solution; then through the impurity removal reaction and calcium precipitation reaction of the acid solution, nano calcium carbonate is obtained; the calcium precipitation solution is concentrated by evaporation to obtain ammonium chloride, which is recycled to the acid dissolution process. The disadvantage is that because the calcium content of vanadium-containing steel slag is high, a large amount of acid is needed to participate in the reaction, which is high in cost.

[0007] In summary, whether it is a pyrometallurgical process or a hydrometallurgical process, calcium is regarded as a harmful element. In order to eliminate the influence of calcium-containing phases in the raw material on the extraction of vanadium, sodium salt or strong acid leaching needs to be introduced from the source, which will result in tailings containing sodium / sulfur ions, which are not easy to dispose of and can only be landfilled, polluting the environment, and the existing process has a low recovery rate of vanadium. Therefore, how to realize the clean extraction of valuable metals from vanadium-containing steel slag is of great significance. SUMMARY

[0008] In view of the above, the present application aims to provide a vanadium-iron comprehensive recovery method for vanadium-containing steel slag, which solves the problems of low recovery rate of existing vanadium-containing steel slag, ineffective utilization of calcium, high acid consumption, and environmental unfriendliness.

[0009] The purpose of the present application is mainly realized through the following technical solutions:

[0010] The present application provides a vanadium-iron comprehensive recovery method for vanadium-containing steel slag, comprising:

[0011] Step 1, roasting vanadium-containing steel slag with ammonium sulfate at low temperature to obtain roasting clinker and ammonia-containing tail gas;

[0012] Step 2, absorbing the ammonia-containing tail gas with water to obtain an ammonia water solution;

[0013] Step 3, after the roasting clinker is cooled, first leaching and filtering are performed to obtain a first leaching solution and a first leaching residue;

[0014] Step 4, the pH value of the first leaching solution is adjusted by the ammonia water solution obtained in step 2 to carry out vanadium-iron co-precipitation, and after filtration, a first mother liquor and a filter residue are obtained, and the filter residue is a mixture of yellow ammonium iron and ammonium polyvanadate;

[0015] Step 5, the mixture of yellow ammonium iron and ammonium polyvanadate is subjected to second leaching and filtration to obtain a second leaching solution and unreacted yellow ammonium iron;

[0016] Step 6, the second leaching solution is subjected to cooling crystallization to obtain ammonium metavanadate and a vanadium precipitation mother liquor;

[0017] Step 7, ammonia water and carbon dioxide or ammonium carbonate are added to the first leaching residue to carry out mineralization and carbon sequestration, and filtration is carried out to obtain a mineralization mother liquor and a mineralization residue;

[0018] Step 8, the mineralization mother liquor of step 7 and the first mother liquor of step 4 are subjected to evaporation crystallization to obtain ammonium sulfate.

[0019] Further, in step 1, the particle size of the vanadium-containing steel slag is controlled to be 44-150 μm.

[0020] Further, in step 1, the mass ratio of the vanadium-containing steel slag to ammonium sulfate is controlled to be 1:1-1:10.

[0021] Further, in step 3, the first leaching process includes: stirring for 30-120 min at 20-90 ℃.

[0022] Further, in step 3, the liquid-solid ratio of the first leaching is controlled to be 2:1-10:1, and the unit of the liquid-solid ratio is l / g.

[0023] Further, in step 4, the temperature of the first leaching solution during vanadium-iron co-precipitation is controlled to be 30-90 ℃.

[0024] Further, in step 4, the pH value is controlled to be 1-7.

[0025] Further, in step 5, ammonium salt or ammonia water is used for the second leaching, and the ammonium salt uses ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium phosphate or ammonium hydrogen phosphate.

[0026] Further, in step 5, the second leaching process is controlled to include: leaching for 10-120 min at 20-90 ℃.

[0027] Further, in step 6, ammonium metavanadate can obtain vanadium pentoxide after calcination.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] a) The vanadium-containing steel slag vanadium-iron comprehensive recovery method of the present application can realize efficient extraction of vanadium-iron components in the vanadium-containing steel slag after roasting under mild roasting conditions, followed by vanadium-iron co-deposition, vanadium leaching and ammonium jarosite separation. Meanwhile, the calcium-containing tailings can be used as a carbon fixation raw material. The present application has multiple benefits of comprehensive utilization of vanadium, iron and calcium in vanadium-containing solid waste, valuable metal recovery, calcium-containing tailings utilization and high purity of vanadium products. The vanadium extraction rate of the roasted slag is greater than 97%, the iron extraction rate is greater than 97%, and the conversion rate of calcium is greater than 95%.

[0030] b) The vanadium-containing steel slag vanadium-iron comprehensive recovery method of the present application can mineralize and sequester carbon dioxide using calcium elements in the vanadium-containing steel slag, and can sequester ≥270 kg of CO2 per ton of vanadium-containing steel slag.

[0031] c) The technical process of the present application is simple, and can recover valuable metals vanadium and iron while taking into account the utilization of calcium and the fixation of carbon dioxide. Moreover, the technical route of the present application does not need to use acid, and is environmentally friendly. The method of the present application can recover valuable metals vanadium and iron while achieving the purpose of waste control by waste, and has the prospect of large-scale popularization and application.

[0032] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the structure particularly pointed out in the written description, claims, and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0034] Figure 1 The process flow chart of the vanadium-containing steel slag vanadium-iron comprehensive recovery method of the present application;

[0035] Figure 2 The XRD pattern of the first leaching residue of Example 1;

[0036] Figure 3 The XRD pattern of the ammonium metavanadate crystal of Example 1;

[0037] Figure 4 The SEM-EDS pattern of the ammonium metavanadate crystal of Example 1;

[0038] Figure 5 The XRD pattern of the vanadium pentoxide of Example 1;

[0039] Figure 6 The SEM-EDS pattern of the vanadium pentoxide of Example 1;

[0040] Figure 7 is an XRD pattern of a mixture of jarosite and ammonium polyvanadate of Example 1;

[0041] Figure 8 is an SEM-EDS pattern of a mixture of jarosite and ammonium polyvanadate of Example 1. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present application will be described in detail below with reference to the drawings, in which the drawings constitute a part of this application and illustrate embodiments of the present application together with the principles of the present application.

[0043] The present application provides a vanadium-containing steel slag vanadium-iron comprehensive recovery method, comprising:

[0044] Step 1, low-temperature roasting vanadium-containing steel slag with ammonium sulfate to obtain roasting clinker and ammonia-containing tail gas;

[0045] Step 2, the ammonia-containing tail gas is absorbed by water to obtain an ammonia water solution;

[0046] Step 3, after the roasting clinker is cooled, first leaching and filtration are performed to obtain a first leaching solution and a first leaching residue;

[0047] Step 4, the pH value of the first leaching solution is adjusted by using the ammonia water solution obtained in Step 2 to co-precipitate vanadium and iron, and after filtration, a first mother liquor and a filter residue are obtained, and the filter residue is a mixture of jarosite and ammonium polyvanadate;

[0048] Step 5, the mixture of jarosite and ammonium polyvanadate is subjected to second leaching and filtration by using an ammonium salt or ammonia water to obtain a second leaching solution and unreacted jarosite;

[0049] Step 6, the second leaching solution is subjected to cooling crystallization to obtain ammonium metavanadate and a vanadium precipitation mother liquor;

[0050] Step 7, ammonia water and carbon dioxide or ammonium carbonate are added to the first leaching residue to indirectly mineralize and fix carbon, and filtration is performed to obtain a mineralized mother liquor rich in ammonium sulfate and a mineralized residue;

[0051] Step 8, the mineralized mother liquor of Step 7 and the first mother liquor of Step 4 are subjected to evaporation crystallization to obtain ammonium sulfate.

[0052] Specifically, in Step 1, the phase of the vanadium-containing steel slag mainly includes calcium silicate, calcium-titanium oxide, oxide phase RO (a solid solution composed of FeO, MnO, and MgO), calcium ferrite, free calcium oxide, and iron spinel, etc.

[0053] Specifically, in the step 1, the chemical composition (wt%) of the vanadium-containing steel slag mainly includes: 32% to 41% CaO, 20% to 23% Fe2O3, 3% to 15% MgO, 11% to 15% SiO2, 2% to 6.5% Al2O3, 0.2% to 3.5% P2O5, 1% to 4% V2O5, 1% to 5% TiO2, 0.8% to 5% MnO, and other oxygen-containing compounds.

[0054] Specifically, in the step 1, considering that the particle size of the vanadium-containing steel slag is too large, which easily leads to incomplete roasting reaction, or too small, which increases the grinding cost. Therefore, the particle size of the vanadium-containing steel slag is controlled to be 44 to 150 μm.

[0055] Specifically, in the step 1, considering that the mass ratio of the vanadium-containing steel slag to ammonium sulfate is too large, which leads to insufficient addition of ammonium sulfate, or too small, which causes excessive addition of ammonium sulfate, thereby increasing the loss of ammonium sulfate. Therefore, the mass ratio of the vanadium-containing steel slag to ammonium sulfate is controlled to be 1:1 to 1:10.

[0056] Specifically, in the step 1, considering that the roasting temperature is too high, which causes the decomposition side reaction of ammonium sulfate to occur, or too low, which leads to incomplete roasting reaction; the roasting time is too long, which increases the roasting energy consumption, or too short, which leads to incomplete roasting reaction. Therefore, the roasting temperature is controlled to be 250 to 450 °C, preferably 250 to 350 °C, and the roasting time is controlled to be 30 to 300 min, for example, 90 to 300 min.

[0057] Specifically, in the step 1, the roasting can be performed in a tube furnace. Considering that the heating rate is too fast, which leads to too short roasting time and incomplete roasting, or too small, which increases the roasting time. Therefore, the heating rate is controlled to be 5 to 10 °C / min to the roasting temperature.

[0058] Specifically, in the step 3, considering that the temperature of the first leaching is too high, which increases the leaching energy consumption, or too low, which reduces the molecular motion rate and the reaction efficiency; the leaching time is too long, which reduces the reaction efficiency, or too short, which leads to incomplete leaching. Therefore, the process of the first leaching includes: stirring at 20 to 90 °C for 30 to 120 min.

[0059] Specifically, in the step 3, considering that the liquid-solid ratio of the first leaching is too high, which causes excessive addition of leaching agent and waste of leaching agent; or too low, which leads to insufficient addition of leaching agent and incomplete leaching. Therefore, the liquid-solid ratio (l / g) of the first leaching is controlled to be 2:1 to 10:1.

[0060] Specifically, in the step 3, the first leaching solution is rich in vanadium and iron ions.

[0061] Specifically, in the step 3, the first leaching residue is rich in calcium sulfate and silicon dioxide.

[0062] Specifically, in the step 3 above, the vanadium and iron leaching rate calculation formula is as follows:

[0063]

[0064] Wherein: c x , V x are the concentration and volume of the leaching solution, respectively, with units of g / L and L; m0 is the mass of the vanadium-containing steel slag, with units of g; w x is the mass fraction of vanadium / iron in the vanadium-containing steel slag, with units of %.

[0065] Specifically, in the step 4 above, considering that the temperature of the first leaching solution is too high when vanadium and iron are co-precipitated, the solution volatilizes seriously; if it is too low, the reaction rate is slow. Therefore, the temperature of the first leaching solution when vanadium and iron are co-precipitated is controlled to be 30-90°C. Preferably, the temperature of the first leaching solution when vanadium and iron are co-precipitated is controlled to be 50-80°C.

[0066] Specifically, in the step 4 above, considering that the pH value is too low when vanadium and iron are co-precipitated, the vanadium and iron precipitate incompletely; if it is too high, other impurity elements are precipitated, affecting the purity of the vanadium and iron co-precipitate. Therefore, the pH value is controlled to be 1-7. Preferably, the pH value is controlled to be 2.5-5.

[0067] Specifically, in the step 5 above, the ammonium salt can use one or a mixture of several reagents of ammonium carbonate, ammonium bicarbonate, ammonia, ammonium oxalate, ammonium phosphate or ammonium hydrogen phosphate.

[0068] Specifically, in the step 5 above, considering that the temperature of the second leaching is too high, the ammonium salt is easy to decompose; if it is too low, the reaction time is increased and the reaction efficiency is reduced. Therefore, the second leaching process is controlled to be 20-90°C, leaching for 10-120 min. Preferably, leaching is carried out at 40-70°C.

[0069] Specifically, in the step 5 above, considering that the liquid-solid ratio of the second leaching is too high, the leaching agent is too much, causing waste; if it is too low, the amount of leaching agent used is insufficient, leading to incomplete reaction. Therefore, the liquid-solid ratio (l / g) of the second leaching is controlled to be 2:1-20:1, preferably the liquid-solid ratio (l / g) of the second leaching is 5:1-10:1.

[0070] Specifically, in the step 5 above, the molar ratio of NH4 + to V in the ammonium salt leaching is 1:1-10:1, preferably 2:1-5:1.

[0071] Specifically, in the step 5 above, the second leaching solution is rich in ammonium metavanadate.

[0072] Specifically, in the above step 6, the second leaching solution is cooled and crystallized to precipitate vanadium at 20-50℃, the concentration of ammonium metavanadate before crystallization is 10-30g / L, the stirring speed is 100-500r / min, and the seed crystal addition amount is 0.1%-3% of the mass of ammonium metavanadate in the solution, for example, the seed crystal addition amount is 0.5%-1.0% of the mass of ammonium metavanadate in the solution. Among them, the seed crystal can be one or a combination of ammonium metavanadate, ammonium polyvanadate, and vanadium pentoxide, and is preferably ammonium metavanadate.

[0073] Specifically, in the above step 6, if the cooling and crystallization temperature is too high, the solubility of ammonium metavanadate is too large and the supersaturation is too small, resulting in low crystallization efficiency; if the cooling temperature is too low, it needs to artificially create low temperature to increase energy consumption. Therefore, the temperature for crystallization and precipitation of vanadium is controlled to be 20-50℃.

[0074] Specifically, in the above step 6, in order to control the crystal nucleus growth and the number of nucleation, the stirring speed is selected to be 100-500r / min.

[0075] Specifically, in the above step 6, if the seed crystal addition amount is too large, the seed crystal is wasted, and if it is too small, it affects the formation of crystal nucleus. Therefore, the seed crystal addition amount is selected to be 0.1%-3% of the mass of ammonium metavanadate in the solution.

[0076] Specifically, in the above step 6, the vanadium precipitation mother liquor can be recycled to leach the filter residue of step 4, and ammonium metavanadate can be calcined at 350-500℃ to obtain vanadium pentoxide.

[0077] Specifically, in the above step 7, the mineralized slag can be used as a cement additive.

[0078] Specifically, in the above step 7, if the temperature of indirect mineralization and carbon sequestration is too high, the liquid will volatilize seriously; if it is too low, the reaction rate will be too slow, reducing the reaction efficiency. Therefore, the temperature for indirect mineralization and carbon sequestration is controlled to be 30-80℃, and the time is 10-300min. Preferably, the temperature for indirect mineralization and carbon sequestration is 30-75℃.

[0079] Specifically, in the above step 7, if the liquid-solid ratio of indirect mineralization and carbon sequestration is too high, the solution containing carbon source is too excessive, resulting in incomplete carbon sequestration; if it is too low, the slurry is too thick and not easy to filter and separate, and the leaching solution is difficult to recycle. Therefore, the liquid-solid ratio (l / g) is controlled to be 1:1-20:1; the molar ratio of CO3 2- / HCO3 - and SO4 2- is too high, causing waste of reagents, and too low, the amount of carbonate / bicarbonate is not enough, affecting the carbon sequestration efficiency. Therefore, the molar ratio of CO3 2- / HCO3 - and SO4 2- is controlled to be 1:1-5:1. Preferably, the molar ratio of CO32- / HCO3 - With SO4 2- The molar ratio is 1:1~3:1.

[0080] Specifically, in step 7, the conversion rate of Ca in the mineralization step is calculated according to the following formula:

[0081]

[0082] Wherein: η Ca The conversion rate of Ca is %, c1 and c2 are the mass concentrations of Ca ions in the solution before and after the mineralization reaction, and the unit is g / l; V1 and V2 are the volumes of the solution before and after the reaction, and the unit is ml.

[0083] In the mineralization step, the calculation formula of the CO2 mineralization rate is as follows:

[0084]

[0085] Wherein: The mineralization rate is kg / t; m3 and m4 represent the mass of a certain substance before and after mineralization and carbon sequestration, respectively, and the unit is g; c3 and c4 represent the mass fraction of C element before and after mineralization and carbon sequestration. CO2 , M C Represent the molar mass of CO2 and C, respectively, and the unit is g / mol.

[0086] Specifically, in step 8, the obtained ammonium sulfate can be recycled to step 1 as a roasting additive for vanadium-containing steel slag, realizing the recycling of ammonium sulfate.

[0087] Compared with the prior art, the vanadium-containing steel slag vanadium-iron comprehensive recovery method of the present application can realize efficient extraction of vanadium-iron components in vanadium-containing steel slag after roasting under mild roasting conditions, and the tailings can be used as a carbon sequestration raw material. The present application has multiple benefits of comprehensive utilization of vanadium, iron and calcium in vanadium-containing solid waste, valuable metal recovery, calcium-containing tailings utilization and high purity of vanadium products. The vanadium extraction rate is greater than 97%, the iron extraction rate is greater than 97%, and the conversion rate of calcium is greater than 95%.

[0088] The vanadium-containing steel slag vanadium-iron comprehensive recovery method of the present application uses calcium elements in vanadium-containing steel slag to mineralize and sequester carbon dioxide, and can sequester ≥270kg CO2 per ton of vanadium-containing steel slag.

[0089] The preparation method is simple, low in cost, and capable of recovering valuable metals vanadium and iron, utilizing calcium, and fixing carbon dioxide. The preparation method does not need to use acid, is environmentally friendly, capable of achieving the purpose of waste treatment with waste while recovering valuable metals vanadium and iron, and has the prospect of large-scale popularization and application.

[0090] The advantages of the vanadium-iron comprehensive recovery method of the vanadium-containing steel slag are shown by specific examples and comparative examples. The examples of the present application all provide a vanadium-iron comprehensive recovery method of vanadium-containing steel slag.

[0091] Example 1:

[0092] The example provides a vanadium-iron comprehensive recovery method of vanadium-containing steel slag. The chemical composition (wt%) of the vanadium-containing steel slag of the example includes 32.09% CaO, 20.28% Fe2O3, 14.79% MgO, 11.1% SiO2, 6.09% Al2O3, 0.21% P2O5, 1.05% V2O5, 1.04% TiO2, 0.85% MnO, and other oxides. The vanadium-iron comprehensive recovery method of the vanadium-containing steel slag of the example is as shown in Figure 1 , and specifically includes:

[0093] (1) The vanadium-containing steel slag is sieved to -125 μm and uniformly mixed with ammonium sulfate, and the mass ratio of the vanadium-containing steel slag to ammonium sulfate is controlled to be 1:10.

[0094] (2) The mixture obtained in step (1) is placed in a tubular furnace, and is programmed to be heated to 350℃ at a rate of 10℃ / min for 120 min. After the reaction, the calcined clinker is cooled to room temperature, and ammonia gas generated in the calcination process is absorbed with water.

[0095] (3) The calcined clinker obtained in step (2) is leached with water, and is stirred at a temperature of 70℃ for 90 min. The liquid-solid ratio (l / g) is controlled to be 3:1. The first leaching solution rich in vanadium and iron ions and the first leaching residue mainly composed of CaSO4 and SiO2 are obtained by filtration separation.

[0096] (4) The first leaching solution obtained in step (3) is stirred and heated to 80℃, and ammonia water is added to the solution to a pH value of 2.5. After the reaction is completed, the first mother liquor and the filter residue are obtained by filtration. The filter residue is the precipitate of ammonium jarosite and ammonium polyvanadate.

[0097] (5) The filter residue obtained in step (4) is added to an ammonium bicarbonate solution, and is leached by stirring and heating to 70℃. The leaching time is 30 min, and the liquid-solid ratio (l / g) is 5:1. NH4 +The molar ratio of V to SO4 is 3:1. After the end of leaching, a second leaching solution and unreacted Huang'an iron vitriol are obtained, and the concentration of ammonium metavanadate in the leaching solution is 25 g / L.

[0098] (6) The second leaching solution obtained in step (5) is subjected to cooling crystallization, the cooling temperature is 30°C, the stirring speed is 200 r / min, and the amount of crystal seed (the crystal seed is ammonium metavanadate) added is 1.0% of the mass of ammonium metavanadate in the solution. The ammonium metavanadate solid obtained by crystallization is calcined at 400°C to obtain powder V2O5.

[0099] (7) The first leaching residue obtained in step (2) is added to an aqueous ammonia solution and subjected to indirect mineralization by passing CO2 gas, the mineralization temperature is 75°C, the reaction time is 30 min, the liquid-solid ratio is 3:1, and the molar ratio of CO3 2- / HCO3 - to SO4 is 3:1. 2-

[0100] (8) The mineralization mother liquor and the first mother liquor obtained in step (7) are subjected to evaporation crystallization to obtain ammonium sulfate, which is used as a roasting additive in step 1, realizing the recycling of ammonium sulfate.

[0101] Analysis shows that under the process conditions, the leaching rate of V in the ammonium sulfate low-temperature roasting-leaching process is 95%, the leaching rate of Fe is 95%, the purity of V2O5 is 99.4%, the conversion rate of Ca in the mineralization step is 96%, and the total CO2 mineralization rate is 287.8 kg / t of vanadium-containing steel slag.

[0102] Example 2:

[0103] The present embodiment provides a vanadium-iron comprehensive recovery method for vanadium-containing steel slag. The chemical composition (wt%) of the vanadium-containing steel slag of the present embodiment includes 40.86% CaO, 22.87% Fe2O3, 3.26% MgO, 14.44 SiO2, 3.85 Al2O3, 3.25% P2O5, 2.56% V2O5, 2.83% TiO2, 4.54% MnO, and other oxides. The vanadium-iron comprehensive recovery method for vanadium-containing steel slag of the present embodiment is as shown in Figure 1 , and specifically includes:

[0104] (1) The vanadium-containing steel slag is sieved to -75 μm and uniformly mixed with ammonium sulfate, and the mass ratio of vanadium-containing steel slag to ammonium sulfate is controlled to be 1:6.

[0105] (2) The mixture obtained in step (1) is placed in a tubular furnace and subjected to roasting at a rate of 10°C / min to 300°C for 90 min. After the reaction, the roasted clinker is cooled to room temperature, and ammonia gas generated during the roasting process is absorbed with water.

[0106] ​(3) The calcined clinker obtained in step (2) is leached with water, stirred at 90°C for 100 min, and the liquid-solid ratio (l / g) is controlled at 10:1. The first leaching solution rich in vanadium and iron ions and the first leaching residue mainly composed of CaSO4 and SiO2 are separated by filtration.

[0107] (4) The first leaching solution obtained in step (3) is stirred and heated to 90°C, and ammonia water is added to a pH value of 3.0. After the reaction is completed, the first mother liquor and the filter residue are obtained by filtration, and the filter residue is the yellow ammonium jarosite and ammonium polyvanadate precipitate.

[0108] (5) The filter residue obtained in step (4) is added to a mixed solution of ammonium oxalate and ammonia water, and leaching reaction is carried out by stirring and heating to 50°C. The leaching conditions are time of 120 min, liquid-solid ratio (l / g) of 10:1, NH4 + / V molar ratio of 5:1 in the solution, and the second leaching solution and unreacted yellow ammonium jarosite are obtained after leaching. The concentration of ammonium metavanadate in the leaching solution is 25 g / L.

[0109] (6) The second leaching solution obtained in step (5) is cooled and crystallized, the cooling temperature is 25°C, the stirring speed is 400 r / min, and the amount of seed crystal (seed crystal is ammonium metavanadate) added is 0.5% of the mass of ammonium metavanadate in the solution. The ammonium metavanadate solid obtained by crystallization is calcined at 380°C to obtain powder-like V2O5.

[0110] (7) The first leaching residue obtained in step (2) is added to an ammonia water solution and indirectly mineralized by passing CO2 gas. The mineralization temperature is 55°C, the reaction time is 250 min, the liquid-solid ratio is 10:1, and the molar ratio of CO3 2- / HCO3 - / SO4 2- is 2:1.

[0111] (8) The mineralized mother liquor and the first mother liquor obtained in step (7) are evaporated and crystallized to obtain ammonium sulfate, which is used as a calcination additive in step 1, realizing the recycling of ammonium sulfate.

[0112] Analysis shows that under the process conditions, the leaching rate of V is 98%, the leaching rate of Fe is 99%, the purity of V2O5 is 98.9%, the conversion rate of Ca in the mineralization step is 99%, and the total CO2 mineralization rate is 294.9 kg / t of vanadium-containing steel slag.

[0113] Example 3:

[0114] The embodiment provides a vanadium-containing steel slag vanadium-iron comprehensive recovery method, and the chemical composition (mass percentage, wt%) of the vanadium-containing steel slag in the embodiment includes 40.51% CaO, 21.83% Fe2O3, 11.80% MgO, 11.23% SiO2, 2.79% Al2O3, 1.35% P2O5, 3.63% V2O5, 4.82% TiO2, 1.70% MnO and other oxides; the vanadium-containing steel slag vanadium-iron comprehensive recovery method process in the embodiment is as shown in the figure, and specifically includes: Figure 1

[0115] (1) The vanadium-containing steel slag is uniformly mixed with ammonium sulfate by sieving to-45μm, and the mass ratio of the vanadium-containing steel slag to the ammonium sulfate is controlled to be 1:3.

[0116] (2) The mixture obtained in step (1) is placed in a tubular furnace, and is programmed to be heated to 250℃ at a rate of 10℃ / min for 300min, the roasted clinker is cooled to room temperature after reaction, and ammonia gas generated in the roasting process is absorbed by water.

[0117] (3) The roasted clinker obtained in step (2) is leached with water, stirring is carried out at 30℃ for 50min, and the liquid-solid ratio (l / g) is controlled to be 5:1, so that the first leaching solution rich in vanadium and iron ions and the first leaching residue mainly composed of CaSO4 and SiO2 are obtained through filtration separation.

[0118] (4) The first leaching solution obtained in step (3) is stirred and heated to 60℃, and ammonia water is added to the first leaching solution to make the pH value be 5.0, and after the reaction is completed, the first mother liquor and the filter residue are obtained through filtration, and the filter residue is the yellow ammonium jarosite and the ammonium polyvanadate precipitate.

[0119] (5) The filter residue obtained in step (4) is added to a mixed solution of ammonium carbonate and ammonium bicarbonate, and leaching reaction is carried out by stirring and heating to 40℃, the leaching time is 100min, the liquid-solid ratio (l / g) is 10:1, the molar ratio of NH4 + to V in the solution is 5:1, and the second leaching solution and the unreacted yellow ammonium jarosite are obtained after the leaching is completed, and the concentration of ammonium metavanadate in the leaching solution is 15g / L.

[0120] (6) The second leaching solution obtained in step (5) is subjected to cooling crystallization, the cooling temperature is 20℃, the stirring speed is 400r / min, and the seed (the seed is ammonium metavanadate) is added in an amount of 0.5% of the mass of ammonium metavanadate in the solution. The ammonium metavanadate solid obtained by crystallization is calcined at 500℃ to obtain powder-like V2O5.

[0121] (7) The first leaching residue obtained in step (2) is added to an ammonia water solution, and indirect mineralization is carried out by introducing CO2 gas, the mineralization temperature is 30℃, the reaction time is 300min, and the liquid-solid ratio is 10:1.​2- / HCO3 - With SO4 2- The molar ratio is 5:1.

[0122] (8) The mineralized mother liquor obtained in step (7) and the first mother liquor are evaporated and crystallized to obtain ammonium sulfate, which is used as the roasting additive in step 1 to realize the recycling of ammonium sulfate.

[0123] Analysis revealed that under these process conditions, the leaching rates of V and Fe in the low-temperature roasting-leaching process of ammonium sulfate were 98%, the purity of V2O5 was 98.0%, the conversion rate of Ca in the mineralization step was 98%, and the total CO2 mineralization rate was 313.6 kg / t of vanadium-containing steel slag.

[0124] Figure 2 The XRD pattern of the first leaching residue of Example 1; Figure 3 This is the XRD pattern of ammonium metavanadate crystals from Example 1; Figure 4 This is a SEM-EDS image of ammonium metavanadate crystals from Example 1; Figure 5 This is the XRD pattern of vanadium pentoxide from Example 1; Figure 6 This is the SEM-EDS image of vanadium pentoxide from Example 1; Figure 7 This is the XRD pattern of the mixture of flamonin ferric sulfate and ammonium polyvanadate from Example 1; Figure 8 This is a SEM-EDS image of the mixture of flavonoids and ammonium polyvanadate from Example 1. Figure 2 It can be seen that the first leaching residue mainly consists of calcium sulfate and silicon dioxide; Figure 3 It can be seen that the product of cooling crystallization is ammonium metavanadate; from Figure 4 It can be seen that the crystallized product of ammonium metavanadate is cylindrical with a complete crystal form; from Figure 5 It can be seen that the substance of ammonium metavanadate after calcination is vanadium pentoxide; from Figure 6 It can be seen that vanadium pentoxide is in the form of fine particles, exhibiting an aggregated state; from Figure 7 It can be seen that the vanadium-iron coprecipitate consists of flammortium ferric sulfate and ammonium polyvanadate; from Figure 8 It can be seen that the vanadium-iron coprecipitate is an irregular large-particle aggregate.

[0125] The inventors conducted extensive research during the research process, and some of the less effective methods are listed below as comparative examples:

[0126] Comparative Example 1:

[0127] The comparative example provides a vanadium-iron comprehensive recovery method of vanadium-containing steel slag. The chemical composition (wt%) of the vanadium-containing steel slag of the comparative example includes 32.09% CaO, 20.28% Fe2O3, 14.79% MgO, 11.1% SiO2, 6.09% Al2O3, 0.21% P2O5, 1.05% V2O5, 1.04% TiO2, 0.85% MnO and other oxides; the vanadium-iron comprehensive recovery method of the vanadium-containing steel slag of the comparative example is substantially the same as that of example 1, except that the vanadium-iron is recovered by stepwise recovery of iron and then vanadium in the comparative example 1; and the vanadium-iron co-precipitate is obtained by co-precipitation of vanadium and iron in example 1, and then the vanadium is leached and the jarosite is separated by using ammonium salt.

[0128] Step 1, first, the first leaching solution of the comparative example is subjected to iron precipitation.

[0129] Specifically, the first leaching solution is heated, and ammonia water is added to adjust the pH value of the filtrate while the temperature is rising. The reaction is continuously stirred during the process. After the reaction is completed, the filtrate is filtered to obtain a first mother liquor and a filter residue, and the filter residue is the jarosite.

[0130] Step 2, the first mother liquor obtained in step 1 is subjected to vanadium precipitation.

[0131] Specifically, the vanadium precipitation process is carried out in a water bath, and ammonium sulfate is used as the vanadium precipitation additive. The molar ratio of ammonium in the ammonium salt to vanadium in the leaching solution is 1.5-2.5. The pH value of the system is maintained at 2.5 by adding a 15% sulfuric acid solution. The vanadium precipitation temperature is 80-95°C, and the precipitation is carried out for 60 min. After the precipitation, the solid-liquid is separated by filtration, and the filter cake is repeatedly washed with dilute sulfuric acid with a pH value of 2.5. The polyvanadic acid precipitate and the second mother liquor are obtained. The ammonium polyvanadate is calcined into V2O5 at 450-600°C. The ammonia gas generated in the calcination process is absorbed with dilute sulfuric acid to prepare ammonium sulfate.

[0132] The purity of V2O5 prepared in the comparative example 1 is only 85.6%, while the purity of V2O5 prepared in example 1 is 99.4%.

[0133] Comparative example 2:

[0134] The comparative example provides a vanadium-iron comprehensive recovery method of vanadium-containing steel slag. The chemical composition (wt%) of the vanadium-containing steel slag of the comparative example includes 40.86% CaO, 22.87% Fe2O3, 3.26% MgO, 14.44 SiO2, 3.85 Al2O3, 3.25% P2O5, 2.56% V2O5, 2.83% TiO2, 4.54% MnO and other oxides; the vanadium-iron comprehensive recovery method of the vanadium-containing steel slag of the comparative example is substantially the same as that of example 1, except that the ammonium sulfate roasting temperature is increased to 500°C and the roasting time is 90 min.

[0135] The leaching rate of Comparative Example 2 was 83%, and the leaching rate of Fe was 90%, while the leaching rate of Example 2 was 98%, and the leaching rate of Fe was 99%.

[0136] Comparative Example 3:

[0137] The present comparative example provides a method for comprehensive recovery of vanadium and iron from vanadium-containing steel slag. The chemical composition of the vanadium-containing steel slag of the present comparative example is the same as that of Example 3, which will not be repeated here. The method for comprehensive recovery of vanadium and iron from vanadium-containing steel slag of the present comparative example is substantially the same as that of Example 3, except that the mass ratio of vanadium-containing steel slag to ammonium sulfate is 2:1.

[0138] The leaching rate of Comparative Example 2 was 83%, and the leaching rate of Fe was 90%, while the leaching rate of Example 2 was 98%, and the leaching rate of Fe was 99%.

[0139] The above description is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for comprehensive recovery of vanadium and iron from vanadium-containing steel slag, characterized in that, The application relates to a method for preparing ammonium metavanadate from vanadium-containing steel slag. The method comprises the following steps:

1. roasting vanadium-containing steel slag with ammonium sulfate at low temperature to obtain roasted clinker and ammonia-containing tail gas; 2. absorbing the ammonia-containing tail gas with water to obtain an ammonia water solution; 3. after the roasted clinker is cooled, the first leaching is carried out with water, and the first leaching solution and the first leaching residue are obtained through filtration; 4. the pH value of the first leaching solution is adjusted with the ammonia water solution obtained in step 2 to carry out vanadium-iron co-precipitation, and the first mother liquor and the filter residue are obtained after filtration, wherein the filter residue is a mixture of yellow ammonium iron alum and ammonium polyvanadate; 5. the mixture of the yellow ammonium iron alum and the ammonium polyvanadate is subjected to the second leaching and filtration to obtain the second leaching solution and unreacted yellow ammonium iron alum; 6. the second leaching solution is cooled and crystallized to obtain ammonium metavanadate and a vanadium precipitation mother liquor; 7. the first leaching residue is added with ammonia water and carbon dioxide or ammonium carbonate to carry out mineralization and carbon sequestration, and the mineralization mother liquor and the mineralization residue are obtained through filtration; 8. the mineralization mother liquor in step 7 and the first mother liquor in step 4 are evaporated and crystallized to obtain ammonium sulfate. In step 1, the phase of the vanadium-containing steel slag mainly comprises calcium silicate, calcium-titanium oxide, oxide phase RO, calcium ferrite, free calcium oxide and iron spinel; the oxide phase RO is a solid solution composed of FeO, MnO and MgO; The chemical composition of the vanadium-containing steel slag mainly comprises 32-41% CaO, 20-23% Fe2O3, 3-15% MgO, 11-15% SiO2, 2-6.5% Al2O3, 0.2-3.5% P2O5, 1-4% V2O5, 1-5% TiO2, 0.8-5% MnO and other oxygen-containing compounds. In step 1, the mass ratio of the vanadium-containing steel slag to the ammonium sulfate is controlled to be 1:3-1:

10. In step 3, the first leaching solution is rich in vanadium and iron ions, and the first leaching residue is rich in calcium sulfate and silicon dioxide. In step 4, the temperature of the first leaching solution during vanadium-iron co-precipitation is controlled to be 30-90 DEG C. In step 5, the second leaching is carried out by using an ammonium salt. In step 5, the process of the second leaching is controlled to be 20-90 DEG C and 10-120 min. In step 1, the particle size of the vanadium-containing steel slag is controlled to be 44-150 mu m. In step 1, the mass ratio of the vanadium-containing steel slag to the ammonium sulfate is controlled to be 1:3-1:

6. In step 3, the process of the first leaching is controlled to be 20-90 DEG C and 30-120 min. In step 3, the liquid-solid ratio of the first leaching is controlled to be 2:1-10:1, and the unit of the liquid-solid ratio is l / g. In step 4, the temperature of the first leaching solution during vanadium-iron co-precipitation is controlled to be 50-80 DEG C. In step 4, the pH value is controlled to be 1-7. In step 5, the ammonium salt is ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium phosphate or ammonium hydrogen phosphate. In step 5, the liquid-solid ratio of the second leaching is 2:1~20:1, and the unit of the liquid-solid ratio is l / g; the NH4 + The molar ratio of NH4+to V is 1:1~10:

1.

2. The method according to claim 1, wherein the vanadium-containing steel slag is a vanadium-containing steel slag obtained by a process comprising: melting a steel containing vanadium to obtain molten steel; and cooling the molten steel to obtain a solidified steel containing vanadium. In step 5, the process of the second leaching is controlled to be 40-70 DEG C.

3. The method according to claim 1, wherein the method is characterized by, In step 6, the ammonium metavanadate can be calcined to obtain vanadium pentoxide.

4. The method according to claim 1, wherein the method is characterized by, ​ 5. The method according to claim 1, wherein the method is characterized by, ​ 6. The method according to claim 1, wherein the method is characterized by, ​ 7. The method according to claim 1, wherein the method is characterized by, ​ 8. The method according to claim 1, wherein the method is characterized by, ​ 9. The method according to claim 1, wherein the method is characterized by, ​ 10. The method according to any one of claims 1 to 9, wherein the method is characterized by, ​

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