A method for resource utilization of chromium residue

Abstract

The application provides a resource utilization method of chromium slag, and belongs to the technical field of solid waste resource utilization; in the resource utilization method of chromium slag, the chromium slag is subjected to one-time alkali leaching treatment, phosphorus in the chromium slag is leached out into liquid phase in the form of phosphate, and chromium is retained in solid phase in the form of one-time alkali leaching chromium slag; the phosphate leaching solution after one-time alkali leaching treatment is subjected to cooling crystallization, and phosphate can be obtained, so that the resource utilization of phosphorus is realized; subsequently, the one-time alkali leaching chromium slag is subjected to secondary alkali leaching treatment and tertiary alkali leaching treatment, so that the chromium slag is deeply dephosphorized, the mass percentage of phosphorus in the obtained dephosphorized chromium slag is less than 0.2%, and therefore the obtained dephosphorized chromium slag can be used as iron ore for steelmaking, so that the resource utilization of iron, nickel and chromium is realized; and the resource utilization method of chromium slag provided by the application is simple to operate, has no special requirement on conditions and is environmentally friendly and pollution-free, and is beneficial to actual production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization, and particularly relates to a resource utilization method of chromium slag. BACKGROUND

[0002] Since the main elements of nickel-iron alloy are iron and nickel, the nickel-iron alloy can provide nickel source and iron source for ternary materials and lithium iron phosphate materials, and the nickel-iron alloy has high price advantage and is favored by battery positive material manufacturers. Chromium, as an associated element of nickel, will inevitably be doped with a small amount of chromium in the nickel-iron alloy. In order to obtain pure nickel salt and iron salt, chromium elements will be discharged from the nickel-iron production line in the form of chromium slag. However, chromium compounds contained in the chromium slag are carcinogenic substances, and chromium elements can easily leak during the storage and stacking of the chromium slag, causing serious environmental pollution. For a long time, the reduction, resource utilization and stabilization of chromium slag have attracted widespread attention from the government and all sectors of society.

[0003] In terms of resource utilization of chromium slag, a hollow ultra-light ceramic based on oil-based cuttings and a preparation method thereof directly dopes iron-chromium slag into raw materials to prepare lightweight ceramsite; a method for stepwise resource utilization of calcium-free roasted chromium slag selectively reduces iron and chromium compounds in the chromium slag to obtain metallic iron-chromium and chromium-rich residues, realizing the resource utilization of iron in the iron-chromium slag; and a process for recycling and preparing chromium oxide from chromium-containing electroplating sludge extracts chromium from the chromium-containing electroplating sludge to prepare sodium dichromate, realizing the resource utilization of chromium in the chromium slag. The above patents include conventional ways of chromium slag resource utilization. The first conventional way is to dope a small proportion of chromium slag into cement and building materials without destroying the composition and structure of the chromium slag, and directly resource utilization of the chromium slag; the second conventional way is to separate high-content elements in the chromium slag to realize the resource utilization of other valuable elements in the chromium slag; and the third conventional way is to extract chromium from the chromium slag to prepare chromium salt. The above methods are all for resource utilization of the chromium slag, but the first conventional way has the problems of low doping proportion and limited utilization of the chromium slag; the second conventional way has the problems of incomplete separation of chromium from other elements and low utilization rate of valuable elements; and the third conventional way has the problem of consumption of a large amount of acid and alkali in the preparation of chromium salt. At the same time, there is no related report on the full-element resource utilization of the chromium slag.

[0004] The main elements of the chromium residue of the ferronickel alloy production line are Fe (about 33%), P (about 15%), Ni (about 1.35%), and Cr (about 0.65%), wherein Fe, Ni, and Cr are main elements for steelmaking, but P is a harmful element for steelmaking. The requirement for P in the raw material for steelmaking is very strict (the standard for iron ore for steelmaking requires that the content of P is less than 0.25%, and the standard for iron ore for ironmaking requires that the content of P is less than 0.15%, which is recorded in the “Geological and Mineral Industry Standard of the People's Republic of China DZ / T 0200-2002 Iron Manganese Chromium Ore Geological Exploration Standard”. After the conversion of iron hydroxide into iron oxide, according to the iron element content as the basis, the content of P in the iron hydroxide is less than 0.2% to meet the standard. If the content of P in the chromium residue can be reduced to below 0.2%, the mixture containing Fe, Ni, and Cr can be used in the steel and iron smelting industry. If the content of P cannot be reduced to the standard range, the mixture containing Fe, Ni, and Cr still belongs to hazardous waste due to the presence of Cr, and cannot be effectively utilized. That is, the selective leaching of P and the reduction of the content of P to below 0.2% are the key to the resource utilization of the chromium residue. However, the prior art does not disclose the selective extraction and leaching of P from the chromium residue. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a resource utilization method of chromium residue, which can utilize all elements in the chromium residue.

[0006] To achieve the above purpose, in the first aspect of the present application, the present application provides a resource utilization method of chromium residue, which comprises the following steps:

[0007] (1) After washing the chromium residue with water, the chromium residue is placed in a first alkali solution for a first reaction. After the first reaction, filtration is performed to obtain a phosphate leaching solution and a first alkali leaching chromium residue;

[0008] (2) The first alkali leaching chromium residue is placed in a second alkali solution for a second reaction. After the second reaction, filtration is performed to obtain a second alkali leaching solution and a second alkali leaching chromium residue;

[0009] (3) The second alkali leaching chromium residue is placed in a third alkali solution for a microwave reaction. After the microwave reaction, filtration is performed to obtain a third alkali leaching solution and a phosphorus-extracted chromium residue.

[0010] The chromium residue resource utilization method provided by the application, through the first alkali leaching treatment of the chromium residue, the phosphorus in the chromium residue is leached out into the liquid phase in the form of phosphate, and the chromium is retained in the solid phase in the form of the first alkali leaching chromium residue; the phosphate leaching solution after the first alkali leaching treatment can obtain phosphate through cooling crystallization, realizing the resource utilization of phosphorus; then the first alkali leaching chromium residue is subjected to the second alkali leaching treatment and the third alkali leaching treatment, realizing the deep phosphorus extraction of the chromium residue, and the mass percentage of phosphorus in the obtained phosphorus extraction chromium residue is less than 0.2%, so that the obtained phosphorus extraction chromium residue can be used as iron ore for steelmaking, thereby realizing the resource utilization of iron, nickel and chromium. Moreover, in the resource utilization method provided by the application, the obtained mother liquor, the second alkali leaching solution and the third alkali leaching solution can be returned to the first alkali solution for recycling, realizing the recycling of the alkali solution, and achieving the resource utilization mode which is environmentally friendly and friendly to the environment.

[0011] In an embodiment, the chromium residue includes chromium residue generated in the process of producing nickel salt and / or iron salt from nickel-iron alloy.

[0012] In an embodiment, the mass percentage of iron is 30-40%, the mass percentage of phosphorus is 12-18%, the mass percentage of nickel is 1-1.7%, and the mass percentage of chromium is 0.5-2.0% in the chromium residue.

[0013] The application researches and finds that the elements in the chromium residue generated in the process of producing nickel salt and / or iron salt from nickel-iron alloy mainly include iron, phosphorus, nickel and chromium, and the main phases are hydrated iron phosphate and hydroxy iron phosphate; after the resource utilization method provided by the application is used for treatment, phosphate can be recycled, and the mass percentage of phosphorus in the obtained phosphorus extraction chromium residue is less than 0.2%, which can be used as iron ore for steelmaking; thereby realizing the comprehensive resource utilization of all elements in the chromium residue generated in the process of producing nickel salt and / or iron salt from nickel-iron alloy.

[0014] In an embodiment, the ratio of the sum of the positive charge moles of metal ions in the chromium residue to the moles of hydroxide in the first alkali solution is 1:(1-5).

[0015] In an embodiment, the ratio of the sum of the positive charge moles of metal ions in the first alkali leaching chromium residue to the moles of hydroxide in the second alkali solution is 1:(1-8).

[0016] In an embodiment, the ratio of the sum of the positive charge moles of metal ions in the second alkali leaching chromium residue to the moles of hydroxide in the third alkali solution is 1:(1-8).

[0017] The present application researches and finds that, no matter the ratio of the sum of the positive charge molar number of metal ions in the chromium residue to the molar number of hydroxide in the primary alkali, the ratio of the sum of the positive charge molar number of metal ions in the primary alkali leaching chromium residue to the molar number of hydroxide in the secondary alkali, or the ratio of the sum of the positive charge molar number of metal ions in the secondary alkali leaching chromium residue to the molar number of hydroxide in the tertiary alkali, when all of them meet the range given in the present application, it can ensure that the corresponding solid is placed in the alkali, the alkali can be alkaline, thereby realizing the removal of phosphorus.

[0018] It should be noted that the metal ions and their contents in the chromium residue and the alkali leaching chromium residue are tested by ICP method. The metal ions and their contents are obtained by ICP test, and then the sum of the positive charge molar number of metal ions in the corresponding chromium residue and alkali leaching chromium residue is calculated.

[0019] Specifically, taking the ratio of the sum of the positive charge molar number of metal ions in the chromium residue to the molar number of hydroxide in the primary alkali as 1:(1-5) as an example, for example, the chromium residue contains divalent metal elements nickel n1 mol, magnesium n2 mol, …, X nx mol, trivalent metal elements chromium n3 mol, chromium n4 mol, …, Y ny mol, and tetravalent metal element Z nz mol, then the sum of the positive charge molar number of metal ions in the chromium residue M is 2*(n1+n2+…+nx)+3*(n3+n4+…+ny)+4nz mol, and the molar number of hydroxide in the primary alkali is (1-5)M; the ratio of the sum of the positive charge molar number of metal ions in the primary alkali leaching chromium residue to the molar number of hydroxide in the secondary alkali, or the ratio of the sum of the positive charge molar number of metal ions in the secondary alkali leaching chromium residue to the molar number of hydroxide in the tertiary alkali is applicable.

[0020] The present application has no special requirements for the primary alkali, the secondary alkali and the tertiary alkali, and the solutions that can ionize hydroxide in aqueous solution can achieve the effect of the present application.

[0021] In an embodiment, the solutes in the primary alkali, the secondary alkali and the tertiary alkali each independently include at least one of liquid ammonia, ammonia water, sodium hydroxide, potassium hydroxide, magnesium hydroxide, and calcium hydroxide; and the solvents in the primary alkali, the secondary alkali and the tertiary alkali include water.

[0022] The present application uses different solutes in the alkali, and the phosphates obtained after the primary alkali leaching treatment are also different, for example, if the solute is sodium hydroxide, the obtained phosphate is trisodium phosphate dodecahydrate; if the solute is magnesium hydroxide, the obtained phosphate is magnesium phosphate, and so on.

[0023] In an embodiment, the primary alkali, the secondary alkali and the tertiary alkali are selected from sodium hydroxide aqueous solution.

[0024] The application researches and finds that when the first alkali liquor, the second alkali liquor and the third alkali liquor are further selected from sodium hydroxide aqueous solution, the obtained phosphate is trisodium phosphate dodecahydrate, which not only has relatively excellent stability, but also has a wider application range.

[0025] In an embodiment, the liquid-solid ratio of the chromium residue and the first alkali liquor, the first alkali leaching chromium residue and the second alkali liquor, and the second alkali leaching chromium residue and the third alkali liquor is independently (2-6) mL / g.

[0026] The application researches and finds that when the liquid-solid ratio in the third alkali leaching process is further selected to be (2-6) mL / g, the removal of phosphorus in the chromium residue can be better achieved, and the mass percentage of phosphorus in the final phosphorus-extracted chromium residue can be reduced.

[0027] In an embodiment, the environment of the first reaction, the second reaction and the microwave reaction is independently a closed environment, a reduced-pressure environment or an inert gas environment.

[0028] The application researches and finds that ensuring that the reaction environment in the alkali leaching process is a closed environment, a reduced-pressure environment or an inert gas environment can avoid the oxidation of trivalent chromium to hexavalent chromium in the air during the alkali leaching process, thereby avoiding the dissolution of the oxidized hexavalent chromium in the alkali liquor, which leads to the difficulty in the separation of chromium and phosphorus elements in the alkali liquor, and the problem of excessive chromium content in the phosphate product; under the reaction environment given in the application, chromium can remain in the trivalent state, and effective separation of chromium and phosphorus can be achieved, specifically, the trivalent chromium can be completely retained in the solid phase, and the phosphorus is fully extracted into the liquid phase, thereby improving the full-element resource utilization efficiency and effect of the chromium residue.

[0029] In an embodiment, the closed environment includes a closed reaction kettle.

[0030] In an embodiment, the inert gas used in the inert gas environment includes nitrogen and a noble gas.

[0031] In an embodiment, the temperature of the first reaction is 60-90℃, and the time of the first reaction is 2-4h.

[0032] In an embodiment, the temperature of the second reaction is 60-90℃, and the time of the second reaction is 2-4h.

[0033] The application researches and finds that when the temperature and time of the first reaction and the second reaction are further selected to be within the above range, the leaching of phosphorus can be better achieved, the mass percentage of phosphorus in the subsequent phosphorus-extracted chromium residue can be reduced, and the efficient resource utilization of the chromium residue can be achieved.

[0034] In an embodiment, in step (3), the time of the microwave reaction is 5-20 min, the power of the microwave reaction is 500-800 W, and the temperature of the microwave reaction is 60-120℃.

[0035] This invention has found that when a microwave reaction is introduced during the three-stage alkaline leaching process, and the time, power, and temperature of the microwave reaction are selected within the range given in this invention, phosphorus can be extracted more deeply, the mass percentage of phosphorus in the phosphorus-chromium extraction slag can be reduced more effectively, and excellent resource utilization can be achieved.

[0036] This invention does not have special requirements for the filtration method, as long as it can separate solids and liquids; for example, the filtration method of this invention can be any one of pressure filtration, centrifugation, or sedimentation.

[0037] In a second aspect, the present invention provides a phosphorus-chromium extraction slag, which is prepared using the resource utilization method for chromium slag described in the present invention.

[0038] The phosphorus content in the phosphorus-chromium extraction slag provided by this invention is less than 0.2% by mass, which can be used in iron ore for steelmaking, thus achieving efficient utilization of the phosphorus-chromium extraction slag.

[0039] In a third aspect, the present invention provides the application of the phosphorus-chromium slag in iron and steel smelting.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] In the resource utilization method of chromium slag provided by this invention, the chromium slag undergoes a primary alkaline leaching treatment. Phosphorus in the chromium slag is leached into the liquid phase as phosphate, while chromium remains in the solid phase as primary alkaline leached chromium slag. The phosphate leachate after the primary alkaline leaching treatment is cooled and crystallized to obtain phosphate, thus realizing the resource utilization of phosphorus. Subsequently, the primary alkaline leached chromium slag undergoes secondary and tertiary alkaline leaching treatments to achieve deep phosphorus extraction. The resulting phosphorus-enriched chromium slag contains less than 0.2% phosphorus by mass, thus enabling it to be used as iron ore for steelmaking, thereby realizing the resource utilization of iron, nickel, and chromium. Furthermore, in the resource utilization method provided by this invention, the mother liquor, secondary alkaline leaching liquor, and tertiary alkaline leaching liquor can all be returned to the primary alkaline solution, achieving the recycling of the alkaline solution. Besides the two products, phosphate and phosphorus-enriched chromium slag, no other waste residue or waste gas is generated. Therefore, this invention not only eliminates the environmental pollution caused by chromium slag but also avoids other pollution, achieving an environmentally friendly and sustainable resource utilization method. Furthermore, the phosphate and iron ore precursors produced by the resource utilization method of chromium slag provided by this invention are bulk commodities with wide application channels and high market value, i.e., strong economic feasibility; at the same time, the resource utilization method of chromium slag provided by this invention is simple to operate, has no special requirements for conditions, and is conducive to actual production. Attached Figure Description

[0042] Figure 1A process flow diagram of the resource utilization method of the chromium residue provided in Embodiment 1 of the present application is shown. DETAILED DESCRIPTION

[0043] For the purpose of better illustrating the present application, the technical solutions and advantages, the present application will be further described in conjunction with specific embodiments.

[0044] The reagents, methods and equipment used in the present application are all conventional reagents, methods and equipment in the art unless otherwise specified.

[0045] Embodiment 1

[0046] The resource utilization method of the chromium residue provided in Embodiment 1 of the present application is shown in the process flow diagram of the resource utilization method of the chromium residue provided in Embodiment 1 of the present application. Figure 1 Specifically includes the following steps:

[0047] (1) Take 100 g of chromium residue (calculated by chromium residue, the mass percentage of iron element is 33.36%, the mass percentage of phosphorus element is 15.29%, the mass percentage of nickel element is 1.35%, and the mass percentage of chromium element is 0.65%) and add it to 1 L of water at room temperature for stirring, to remove the soluble impurities in the chromium residue; then add the water-washed chromium residue to 300 mL of primary lye (the primary lye is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 75 g; the ratio of the sum of the positive charge molar number of metal ions in the chromium residue to the molar number of hydroxide in the primary lye is 1:3), and a small amount of nitrogen is introduced into the reaction environment to make the first reaction under anoxic conditions, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed, to obtain a sodium phosphate leaching solution and a primary lye leached chromium residue;

[0048] After the sodium phosphate leaching solution is cooled to 45℃, a sodium phosphate crystal seed is added for cooling crystallization, then filtration is performed, the solid is collected and dried at 40℃, to obtain a trisodium phosphate product;

[0049] (2) Add 32 g of the primary lye leached chromium residue to 150 mL of secondary lye (the secondary lye is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar number of metal ions in the primary lye leached chromium residue to the molar number of hydroxide in the secondary lye is 1:4), and a small amount of nitrogen is introduced into the reaction environment to make the second reaction under anoxic conditions, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed, to obtain a secondary lye leaching solution and a secondary lye leached chromium residue;

[0050] (3) 29 g of the secondary alkali leached chromium residue is added into 150 mL of the tertiary alkali liquid (the tertiary alkali liquid is a sodium hydroxide aqueous solution, the mass of the sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the secondary alkali leached chromium residue to the molar number of the hydroxide in the tertiary alkali liquid is 1:6), and microwave reaction is carried out in a closed environment, the microwave reaction time is 15 min, the power is 600 W, and the temperature is 80°C; after the microwave reaction is completed, filtration is performed, and the tertiary alkali leaching liquid and the phosphorus and chromium extracted residue are obtained.

[0051] Example 2

[0052] The embodiment of the present application provides a resource utilization method of chromium residue, and the only difference between the resource utilization method of the chromium residue and the embodiment 1 is that in step (2), 32 g of the primary alkali leached chromium residue is added into 150 mL of the secondary alkali liquid (the secondary alkali liquid is a sodium hydroxide aqueous solution, the mass of the sodium hydroxide is 6 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the primary alkali leached chromium residue to the molar number of the hydroxide in the secondary alkali liquid is 1:3.2); and in step (3), 30 g of the secondary alkali leached chromium residue is added into 150 mL of the tertiary alkali liquid (the tertiary alkali liquid is a sodium hydroxide aqueous solution, the mass of the sodium hydroxide is 6 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the secondary alkali leached chromium residue to the molar number of the hydroxide in the tertiary alkali liquid is 1:5).

[0053] Example 3

[0054] The embodiment of the present application provides a resource utilization method of chromium residue, and the only difference between the resource utilization method of the chromium residue and the embodiment 1 is that in step (2), 32 g of the primary alkali leached chromium residue is added into 150 mL of the secondary alkali liquid (the secondary alkali liquid is a sodium hydroxide aqueous solution, the mass of the sodium hydroxide is 6 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the primary alkali leached chromium residue to the molar number of the hydroxide in the secondary alkali liquid is 1:3.2); and in step (3), 30 g of the secondary alkali leached chromium residue is added into 150 mL of the tertiary alkali liquid (the tertiary alkali liquid is a sodium hydroxide aqueous solution, the mass of the sodium hydroxide is 6 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the secondary alkali leached chromium residue to the molar number of the hydroxide in the tertiary alkali liquid is 1:5).

[0055] Example 4

[0056] (1) take 100 g of chromium slag (the mass percentage of iron element is 33.36%, the mass percentage of phosphorus element is 15.29%, the mass percentage of nickel element is 1.35%, and the mass percentage of chromium element is 0.65% in the chromium slag) and add it into 1 L of water for stirring at room temperature to remove the soluble impurities in the chromium slag; then add the water-washed chromium slag into 300 mL of a first lye (the first lye is a potassium hydroxide aqueous solution, the mass of potassium hydroxide is 105 g; the ratio of the sum of the positive charge molar numbers of metal ions in the chromium slag to the molar number of hydroxide in the first lye is 1:3), and a small amount of nitrogen is introduced into the reaction environment to make the first reaction under the condition of oxygen deficiency, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed to obtain a potassium phosphate leaching solution and a first lye leaching chromium slag;

[0057] cool the potassium phosphate leaching solution to 45℃, then add potassium phosphate crystal seeds for cooling crystallization, and then filter to collect the solid and dry it at 40℃ to obtain a potassium phosphate product;

[0058] (2) add 34 g of the first lye leaching chromium slag into 150 mL of a second lye (the second lye is a potassium hydroxide aqueous solution, the mass of potassium hydroxide is 10 g; the ratio of the sum of the positive charge molar numbers of metal ions in the first lye leaching chromium slag to the molar number of hydroxide in the second lye is 1:4), and a small amount of nitrogen is introduced into the reaction environment to make the second reaction under the condition of oxygen deficiency, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed to obtain a second lye leaching solution and a second lye leaching chromium slag;

[0059] (3) add 31 g of the second lye leaching chromium slag into 150 mL of a third lye (the third lye is a potassium hydroxide aqueous solution, the mass of potassium hydroxide is 10 g; the ratio of the sum of the positive charge molar numbers of metal ions in the second lye leaching chromium slag to the molar number of hydroxide in the third lye is 1:6), and microwave reaction is carried out in a sealed environment, the microwave reaction time is 15 min, the power is 600 W, and the temperature is 80℃; after the microwave reaction is completed, filtration is performed to obtain a third lye leaching solution and a phosphorus-extracted chromium slag.

[0060] Example 5

[0061] The chromium slag resource utilization method provided in the embodiment of the present application is only different from the method in the embodiment 1 in that, in the step (1), the stirring reaction is carried out at 60℃ for 3 h.

[0062] Example 6

[0063] The chromium slag resource utilization method provided in the embodiment of the present application is only different from the method in the embodiment 1 in that, in the step (1), the stirring reaction is carried out at 50℃ for 4 h.

[0064] Example 7

[0065] The embodiment of the present application provides a resource utilization method of chromium slag, and the only difference between the resource utilization method of the chromium slag and the embodiment 1 is that in step (1), the stirring reaction is carried out at 100 DEG C for 4h.

[0066] Embodiment 8

[0067] The embodiment of the present application provides a resource utilization method of chromium slag, and the only difference between the resource utilization method of the chromium slag and the embodiment 1 is that in step (3), the microwave reaction is carried out for 5min, the power is 800W, and the microwave reaction temperature is 60 DEG C.

[0068] Embodiment 9

[0069] The embodiment of the present application provides a resource utilization method of chromium slag, and the only difference between the resource utilization method of the chromium slag and the embodiment 1 is that in step (3), the microwave reaction is carried out for 20min, the power is 500W, and the microwave reaction temperature is 120 DEG C.

[0070] Embodiment 10

[0071] The embodiment of the present application provides a resource utilization method of chromium slag, and the only difference between the resource utilization method of the chromium slag and the embodiment 1 is that in step (3), the microwave reaction is carried out for 15min, and the power is 300W.

[0072] Embodiment 11

[0073] The embodiment of the present application provides a resource utilization method of chromium slag, and the only difference between the resource utilization method of the chromium slag and the embodiment 1 is that in step (3), the microwave reaction is carried out for 15min, and the power is 900W.

[0074] Comparative Example 1

[0075] The comparative example of the present application provides a resource utilization method of chromium slag, and the resource utilization method of the chromium slag comprises the following steps:

[0076] (1) 100g of chromium slag (the mass percentage of iron element is 33.36%, the mass percentage of phosphorus element is 15.29%, the mass percentage of nickel element is 1.35%, and the mass percentage of chromium element is 0.65%) is added into 1L of water for stirring at room temperature to remove the soluble impurities in the chromium slag; then the water-washed chromium slag is added into 300mL of primary lye (the primary lye is sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 75g; the ratio of the sum of the positive charge molar number of metal ions in the chromium slag to the molar number of hydroxyl ions in the primary lye is 1:3), a small amount of nitrogen is introduced into the reaction environment to make the first reaction carried out under the condition of oxygen deficiency, and the stirring reaction is carried out at 80 DEG C for 3h; after the stirring reaction is completed, filtration is carried out to obtain a sodium phosphate leaching solution and a primary lye leaching chromium slag;

[0077] After the sodium phosphate leaching solution is cooled to 45℃, sodium phosphate seed crystals are added for cooling crystallization, followed by filtration, collection of the solid, and drying at 40℃ to obtain a trisodium phosphate product;

[0078] (2) 32 g of the first alkaline leached chromium residue is added to 150 mL of the second alkaline solution (the second alkaline solution is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the first alkaline leached chromium residue to the molar number of hydroxide ions in the second alkaline solution is 1:4), a small amount of nitrogen is introduced into the reaction environment to make the second reaction proceed under anoxic conditions, and the reaction is stirred at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed to obtain a second alkaline leaching solution and a second alkaline leached chromium residue;

[0079] (3) 29 g of the second alkaline leached chromium residue is added to 150 mL of the third alkaline solution (the third alkaline solution is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the second alkaline leached chromium residue to the molar number of hydroxide ions in the third alkaline solution is 1:6), a small amount of nitrogen is introduced into the reaction environment to make the reaction proceed under anoxic conditions, and the reaction is stirred at 80℃ for 3 h; after the stirring reaction is completed, filtration is performed to obtain a third alkaline leaching solution and a phosphorus-extracted chromium residue.

[0080] Comparative Example 2

[0081] The comparative example of the present application provides a method for resource utilization of chromium residue, the only difference between the method for resource utilization of chromium residue and comparative example 1 is that in step (2), 32 g of the first alkaline leached chromium residue is added to 150 mL of the second alkaline solution (the second alkaline solution is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 15 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the first alkaline leached chromium residue to the molar number of hydroxide ions in the second alkaline solution is 1:8); and in step (3), 28 g of the second alkaline leached chromium residue is added to 150 mL of the third alkaline solution (the third alkaline solution is a sodium hydroxide aqueous solution, the mass of sodium hydroxide is 10 g; the ratio of the sum of the positive charge molar numbers of the metal ions in the second alkaline leached chromium residue to the molar number of hydroxide ions in the third alkaline solution is 1:8).

[0082] Comparative Example 3

[0083] The comparative example of the present application provides a method for resource utilization of chromium residue, the method for resource utilization of chromium residue comprises the following steps:

[0084] (1) take 100 g of chromium residue (the mass percentage of iron element is 33.36%, the mass percentage of phosphorus element is 15.29%, the mass percentage of nickel element is 1.35%, and the mass percentage of chromium element is 0.65% in the chromium residue) and add it into 1 L of water for stirring at room temperature to remove the soluble impurities in the chromium residue; then add the water-washed chromium residue into 300 mL of a primary lye (the primary lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 75 g; the ratio of the sum of the positive charge molar numbers of metal ions in the chromium residue to the molar number of hydroxide in the primary lye is 1:3), and perform a microwave reaction in a closed environment, the microwave reaction time is 15 min, the power is 600 W, and the temperature is 80℃; after the microwave reaction, filtration is performed to obtain a sodium phosphate leaching solution and a primary lye-impregnated chromium residue;

[0085] cool the sodium phosphate leaching solution to 45℃, add sodium phosphate crystal seeds for cooling crystallization, then perform filtration, collect the solid, and dry it at 40℃ to obtain a trisodium phosphate product;

[0086] (2) add 32 g of the primary lye-impregnated chromium residue into 150 mL of a secondary lye (the secondary lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of metal ions in the primary lye-impregnated chromium residue to the molar number of hydroxide in the secondary lye is 1:4), introduce a small amount of nitrogen into the reaction environment to make the second reaction performed under anoxic conditions, and perform stirring reaction at 80℃ for 3 h; after the stirring reaction, filtration is performed to obtain a secondary lye leaching solution and a secondary lye-impregnated chromium residue;

[0087] (3) add 29 g of the secondary lye-impregnated chromium residue into 150 mL of a tertiary lye (the tertiary lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of metal ions in the secondary lye-impregnated chromium residue to the molar number of hydroxide in the tertiary lye is 1:6), introduce a small amount of nitrogen into the reaction environment to make the third reaction performed under anoxic conditions, and perform stirring reaction at 80℃ for 3 h; after the stirring reaction, filtration is performed to obtain a tertiary lye leaching solution and a phosphorus-extracted chromium residue.

[0088] Comparative Example 4

[0089] The comparative example of the present application provides a resource utilization method of chromium residue, which comprises the following steps:

[0090] (1) take 100 g of chromium residue (the mass percentage of iron element is 33.36%, the mass percentage of phosphorus element is 15.29%, the mass percentage of nickel element is 1.35%, and the mass percentage of chromium element is 0.65% in the chromium residue) and add it into 1 L of water for stirring at room temperature to remove the soluble impurities in the chromium residue; then the water-washed chromium residue is added into 300 mL of a first lye (the first lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 75 g; the ratio of the sum of the positive charge molar numbers of metal ions in the chromium residue to the molar number of hydroxide in the first lye is 1:3), a small amount of nitrogen is introduced into the reaction environment to make the first reaction carried out under the condition of oxygen deficiency, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is carried out to obtain a sodium phosphate leaching solution and a first lye leaching chromium residue;

[0091] After the sodium phosphate leaching solution is cooled to 45℃, a sodium phosphate crystal seed is added for cooling crystallization, then filtration is carried out, the solid is collected, and drying is carried out at 40℃ to obtain a trisodium phosphate product;

[0092] (2) 32 g of the first lye leaching chromium residue is added into 150 mL of a second lye (the second lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of metal ions in the first lye leaching chromium residue to the molar number of hydroxide in the second lye is 1:4), and microwave reaction is carried out in a closed environment; the time of the microwave reaction is 15 min, the power is 600 W, and the temperature is 80℃; after the microwave reaction is completed, filtration is carried out to obtain a second lye leaching solution and a second lye leaching chromium residue;

[0093] (3) 28 g of the second lye leaching chromium residue is added into 150 mL of a third lye (the third lye is a sodium hydroxide aqueous solution, and the mass of sodium hydroxide is 7.5 g; the ratio of the sum of the positive charge molar numbers of metal ions in the second lye leaching chromium residue to the molar number of hydroxide in the third lye is 1:6.5), a small amount of nitrogen is introduced into the reaction environment to make the reaction carried out under the condition of oxygen deficiency, and the stirring reaction is carried out at 80℃ for 3 h; after the stirring reaction is completed, filtration is carried out to obtain a third lye leaching solution and a phosphorus-extracted chromium residue.

[0094] Effect example

[0095] The parameters of the phosphate and the phosphorus-extracted chromium residue prepared by the resource utilization method of the chromium residue provided in the effect example test examples 1-11 and the comparative examples 1-4 are obtained, wherein,

[0096] The purity of the phosphate = the weight of the dodecahydrate phosphate / the weight of the phosphate solid product obtained in step (1) * 100%;

[0097] The yield of phosphorus = [1 - the content of phosphorus in the phosphorus-extracted chromium residue * the weight of the phosphorus-extracted chromium residue / (the content of phosphorus in the chromium residue * the weight of the chromium residue)] * 100%;

[0098] The obtained results are shown in Table 1;

[0099] Table 1

[0100]

[0101] As can be seen from Table 1, when the resource utilization method provided by the present application is adopted, the comprehensive utilization of all elements in the chromium slag can be effectively realized, wherein the purity of the obtained phosphate is above 98.5%, the yield of phosphorus is above 99.43%, and the obtained sodium phosphate product meets the standard of HG / T 2517-2009 Industrial Trisodium Phosphate, and can be directly used as industrial trisodium phosphate; the mass percentage of phosphorus in the phosphorus-extracted chromium slag is below 0.20%, and the phosphorus-extracted chromium slag meets the industrial index of iron ore for steelmaking (DZ / T0200-2002), and can be used as a steelmaking raw material subsequently;

[0102] As can be seen from Examples 1-3, the ratio of the sum of the positive charge moles of metal ions in the chromium slag to the moles of hydroxide in the alkali solution will affect the purity of the sodium phosphate product and the yield of phosphorus to some extent, and will also have a certain influence on the mass percentage of phosphorus in the phosphorus-extracted chromium slag; as can be seen from Examples 1 and 5-11, the reaction parameters in the resource utilization process will affect the purity of the sodium phosphate product and the yield of phosphorus and the mass percentage of phosphorus in the phosphorus-extracted chromium slag;

[0103] As can be seen from Examples 1 and Comparative Example 1, when the microwave treatment is not introduced in the third alkaline leaching treatment, the mass percentage of phosphorus in the obtained phosphorus-extracted chromium slag is significantly increased, which is 2.5 times that of Example 1, and does not meet the industrial index of DZ / T0200-2002; as can be seen from Examples 1 and Comparative Example 2, when the microwave treatment is not introduced in the third alkaline leaching treatment, even if the addition amount of sodium hydroxide in the second alkaline leaching treatment and the third alkaline leaching treatment is increased, the corresponding phosphorus removal effect cannot be achieved, and the mass percentage of phosphorus in the phosphorus-extracted chromium slag in Comparative Example 2 is 1.8 times that of Example 1; as can be seen from Examples 1 and Comparative Examples 3-4, when the microwave reaction is not introduced in the third alkaline leaching treatment, but in the first alkaline leaching treatment or the second alkaline leaching treatment, the phosphorus content in the phosphorus-extracted chromium slag cannot be effectively reduced.

Claims

1. A method for the resource utilization of chromium slag, characterized in that, The resource utilization method includes the following steps: (1) After washing the chromium slag with water, place it in a primary alkaline solution for the first reaction. After the first reaction is completed, filter to obtain phosphate leachate and primary alkaline leaching of chromium slag. Cool the phosphate leachate to crystallize and obtain phosphate solid and mother liquor. (2) The primary alkali leaching chromium residue is placed in the secondary alkali solution for a second reaction. After the second reaction is completed, it is filtered to obtain the secondary alkali leaching solution and the secondary alkali leaching chromium residue. (3) Place the secondary alkaline leaching chromium residue in the tertiary alkaline solution for microwave reaction. After the microwave reaction is completed, filter to obtain the tertiary alkaline leaching solution and phosphorus-extracting chromium residue. The environments for the first reaction, the second reaction, and the microwave reaction are each independent of a closed environment, a reduced pressure environment, or an inert gas environment; The temperature of the first reaction is 60-90℃, and the reaction time is 2-4 hours. The temperature of the second reaction is 60-90℃, and the reaction time is 2-4 hours. In step (3), the microwave reaction time is 5-20 min, the microwave reaction power is 500-800 W, and the microwave reaction temperature is 60-120 °C.

2. The resource utilization method according to claim 1, characterized in that, The chromium slag includes chromium slag generated during the production of nickel salts and / or iron salts from nickel-iron alloys.

3. The resource utilization method according to claim 1, characterized in that, Based on chromium slag, the mass percentage of iron is 30-40%, the mass percentage of phosphorus is 12-18%, the mass percentage of nickel is 1-1.7%, and the mass percentage of chromium is 0.5-2.0%.

4. The resource utilization method according to claim 1, characterized in that, The ratio of the sum of the positive charge moles of metal ions in the chromium slag to the number of hydroxide ions in the primary alkaline solution is 1:(1-5). And / or, the ratio of the sum of the moles of positive charge of metal ions in the primary alkaline leaching chromium slag to the moles of hydroxide ions in the secondary alkaline solution is 1:(1-8). And / or, the ratio of the sum of the positive charge moles of metal ions in the secondary alkaline leaching chromium slag to the moles of hydroxide ions in the tertiary alkaline solution is 1:(1-8).

5. The resource utilization method according to claim 1, characterized in that, The liquid-solid ratios of the chromium slag and primary alkali solution, the primary alkali leaching chromium slag and secondary alkali solution, and the secondary alkali leaching chromium slag and tertiary alkali solution are each independently (2-6) mL / g.

6. A phosphorus and chromium extraction slag, characterized in that, The phosphorus-chromium slag is prepared using the resource utilization method for chromium slag as described in any one of claims 1-5.

7. The application of the phosphorus and chromium extraction slag as described in claim 6 in iron and steel smelting.

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