A method for preparing feldspar from spent potlining of electrolytic aluminum and the feldspar prepared thereby

Abstract

The present invention relates to a method for preparing feldspar from overhaul slag of electrolytic aluminum and the feldspar obtained thereby, comprising the following steps: mixing the overhaul slag powder of electrolytic aluminum with reaction aid I and subjecting it to heating and roasting in stage I to obtain overhaul slag clinker E; mixing the obtained overhaul slag clinker E with reaction aid II and subjecting it to heating and roasting in stage II to obtain dross F and molten salt H; grinding the obtained dross F into powder, adding reaction aid III and mixing uniformly to obtain mixed material C, and placing the obtained mixed material C in a furnace for heating and roasting in stage III to obtain crude feldspar; and washing and drying the obtained crude feldspar to obtain feldspar. The advantages of the present invention are that through the roasting in stage I, carbon particles, aluminum particles, cyanides, carbides, nitrides, and carbon sodium compounds contained in the overhaul slag are effectively removed, the structure of the original compounds is destroyed, and the overhaul slag becomes porous, facilitating the subsequent separation of fluorides; and through the roasting in stage II, fluorides are effectively separated to obtain a clean feldspar raw material.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of solid hazardous waste in the aluminum industry, and particularly relates to a method for preparing feldspar from overhaul slag of electrolytic aluminum and the feldspar obtained thereby. Background Art

[0002] During the production process of electrolytic aluminum, due to the penetration and corrosion of the high-temperature electrolyte on the lining material, the cathode carbon block is deformed and cracked. The molten aluminum and electrolyte in the cell seep downward along the cracks until reaching the bottom of the furnace, resulting in the abnormal production of the electrolytic cell and the need for a major overhaul. All the used refractory lining materials (referred to as overhaul slag) are removed during the overhaul, and new lining materials are replaced. Overhaul slag is an inevitable solid waste in the production process of electrolytic aluminum. The general composition of overhaul slag (excluding waste carbon blocks) is: fluoride 25%-30%, cyanide about 0.2%, aluminum nitride about 3%, aluminum carbide about 3%, which is highly harmful to the ecological environment. When overhaul slag gets wet in the rain or absorbs moisture, harmful substances will undergo violent chemical reactions with water, releasing toxic and harmful gases. Overhaul slag contains a high concentration of soluble fluoride, which seeps into the ground with rainwater and pollutes the soil and groundwater, forming high-fluoride soil and high-fluoride water. High-fluoride soil and high-fluoride water are highly harmful to the growth of animals and plants, causing the bones of animals / plants to turn black and necrotic and damaging the immune system. The cyanide contained in overhaul slag releases highly toxic HCN gas when exposed to water, and a small amount can cause poisoning. When the concentration of HCN in the inhaled air reaches 0.3 mg / m 3 it can be fatal. When overhaul slag gets wet in the rain, a strong ammonia smell is often smelled. Overhaul slag stored outdoors or temporarily stored in a hazardous waste warehouse is a potential centralized hazard source. In recent years, environmental pollution incidents caused by overhaul slag getting wet in the rain have occurred frequently.

[0003] Feldspar is a kind of aluminosilicate mineral containing calcium, sodium and potassium, with a vitreous luster, various colors, and there are various minerals such as albite, anorthite, orthoclase, etc. Feldspar has a high alumina content and a low iron content. When used as a glass solvent, it can reduce the amount of alkali used. When used as a ceramic glaze, it can make the glaze surface soft and reduce the melting temperature of the glaze. Albite is sodium aluminosilicate (Na2O·Al2O3·6SiO2 or NaAlSi3O8), in which the proportion of Na2O is 11.8%, the proportion of Al2O3 is 19.4%, and the proportion of SiO2 is 68.8%. Albite is a glassy crystal, generally white or grayish-white in appearance, and is a raw material for making glass and ceramics. Orthoclase is potassium aluminosilicate (K2O·Al2O3·6SiO2 or KAlSi3O8), belonging to the monoclinic system, usually in colors such as flesh red, yellow, white, etc. Among them, the proportion of SiO2 is 64.7%, the proportion of Al2O3 is 18.4%, and the proportion of K2O is 16.9%. It has the characteristics of low melting point and high melting viscosity, and is widely used in ceramic billets, ceramic glazes, glass, electroceramics, abrasive materials, etc. Anorthite is calcium aluminosilicate (CaO·Al2O3·2SiO2), white or light gray in color, brittle, glassy crystal, in which the proportion of CaO is 20.1%, the proportion of Al2O3 is 36.7%, and the proportion of SiO2 is 43.2%, and it can be used to make glass and ceramics.

[0004] At present, the main methods for treating overhaul slag at home and abroad are pyrometallurgical treatment and hydrometallurgical treatment. The existing technologies result in the unutilized or incomplete utilization of valuable elements such as F, Si, Al, Li, etc. in the overhaul slag, causing resource waste. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing feldspar from electrolytic aluminum overhaul slag and the feldspar prepared thereby. Using electrolytic aluminum overhaul slag to prepare feldspar can not only reduce environmental pollution and save primary resources, but also effectively utilize industrial secondary resources, generating significant economic and social environmental benefits.

[0006] The present invention is achieved through the following technical solutions: On the one hand, a method for preparing feldspar from electrolytic aluminum overhaul slag includes the following steps:

[0007] Step 1) Crush, grind, screen and homogenize the massive electrolytic aluminum overhaul slag using a crusher to obtain electrolytic aluminum overhaul slag powder with particles ≤ 2 mm.

[0008] Step 2) Mix the electrolytic aluminum overhaul slag powder with reaction auxiliary agent I, and place the obtained mixed material A in a furnace for section I heating and roasting. The roasting temperature is 500 - 700 °C, and the roasting time is 1 - 2 h to obtain overhaul slag clinker E.

[0009] Step 3) Mix the overhaul slag clinker E obtained in step 2) with reaction aid II. Place the obtained mixed material B after mixing evenly in a furnace for stage II heating and roasting. The roasting temperature is 800 - 1000 °C, and the roasting time is 1 - 3 h to obtain floating slag F and molten salt H;

[0010] Step 4) Grind the floating slag F obtained in step 3), add reaction aid III and mix evenly to obtain mixed material C. Place the obtained mixed material C in a furnace for stage III heating and roasting. The roasting temperature is 900 - 1100 °C, and the time is 2 - 4 h to obtain crude feldspar. After washing and drying the crude feldspar, feldspar is obtained; the quality of the obtained feldspar meets the requirements of JC / T859 - 2000.

[0011] Through the above technical solution, chemical reactions occur during the heating and roasting treatment of aluminum electrolysis overhaul slag powder, effectively removing carbon particles, aluminum particles, cyanides, carbides, nitrides, and sodium carbonate compounds contained in the overhaul slag. The newly formed sodium oxide reacts with aluminum oxide and silicon oxide in the waste to form a compound with a porous structure, promoting the infiltration of air and the escape of reaction-generated gases, accelerating the oxidation and decomposition of cyanides, carbides, and nitrides, resulting in the disintegration of the original compound structure in the aluminum electrolysis overhaul slag powder, making the aluminum electrolysis overhaul slag powder loose and porous, and facilitating the subsequent separation of fluorides.

[0012] Further, in step 2), the reaction aid I is composed of starch and stearic acid, and the addition amount of the reaction aid I is 0.01 - 0.07 times the mass of the aluminum electrolysis overhaul slag powder, and a better addition amount is 0.02 - 0.06 times.

[0013] Through the above technical solution, the present invention uses a mixture of starch and stearic acid as a reaction aid, making full use of its characteristics of low ignition point and easy combustion, and the combustion products are clean CO2 and H2O, without bringing in solid impurities. Moreover, starch is rich in hydroxyl groups, and stearic acid belongs to fatty acids. Mixing the two as a reaction aid can effectively promote the chemical reaction of combustible substances in the aluminum electrolysis overhaul slag powder, promote the oxidation and decomposition of cyanides, carbides, and nitrides, and achieve the purpose of destroying the internal structure of the aluminum electrolysis overhaul slag powder.

[0014] Specifically, the main chemical reactions in stage I heating and roasting are as follows:

[0015] C + O2 = CO2 (1)

[0016] 2NaCN + 2.5O2 = Na2O + 2CO2 + N2 (2)

[0017] 2AlN + 1.5O2 = Al2O3 + N2 (3)

[0018] Al4C3 + 6O2 = 2Al2O3 + 3CO2 (4)

[0019] Na4C + 2O2=2Na2O + CO2(5)

[0020] (C6H 10 (C6H10O5)n + 6nO2=6nCO2 + 5nH2O(6)

[0021] C 18 H 36 C18H36O2 + 26O2=18CO2 + 18H2O(7)

[0022] Further, in step 3), the reaction aid II is composed of a mixture of sodium chloride and potassium chloride, and the addition amount of the reaction aid II is 0.3 - 0.7 times the mass of the overhaul slag clinker E, and a better addition amount is 0.4 - 0.6 times.

[0023] Through the above technical solution, the present invention uses a mixture of sodium chloride and potassium chloride as the reaction aid. The aid II is a low - melting - point chloride salt, whose melting point is lower than that of the fluoride salt in the overhaul slag and preferentially melts during the roasting process, promoting the rapid melting of the fluoride in the overhaul slag and converging into the molten salt together with the aid II. This not only effectively reduces the roasting temperature but also avoids the pollution of the fluoride to the subsequent products; through the two - stage heating and roasting treatment, the internal structure of the original minerals is destroyed. As the fluoride melts, the remaining non - melting substances become more porous and float on the surface of the molten salt to form dross, which is conducive to the separation of the fluoride and the dross. All the fluoride enters the molten salt, and the main components of the obtained dross are alumina and silica, thereby obtaining a clean raw material for preparing feldspar.

[0024] A kind of albite is provided, which is prepared by the method for preparing feldspar from electrolytic aluminum overhaul slag as described above; in step 4), the reaction aid III is composed of a mixture of sodium carbonate and sodium bicarbonate, and the dosage of the reaction aid III is 1.0 - 1.2 times the theoretical amount of the reaction between the sodium element of the aid and the aluminum element in the overhaul slag.

[0025] Through the above technical solution, the present invention uses a mixture of sodium carbonate and sodium bicarbonate as the reaction aid III, and the obtained albite has high purity and good quality, meeting the requirements of JC / T859 - 2000.

[0026] Specifically, the main chemical reactions of the three - stage heating and roasting are as follows:

[0027] Na2CO3 + Al2O3 + 6SiO2=Na2O·Al2O3·6SiO2 + CO2(8)

[0028] 2NaHCO3 + Al2O3 + 6SiO2=Na2O·Al2O3·6SiO2 + H2O + 2CO2(9)

[0029] Provided is a potassium feldspar which is prepared by the method for preparing feldspar using overhaul slag of electrolytic aluminum as described above; in step 4), the reaction auxiliary agent III is composed of potassium carbonate and potassium bicarbonate, and the dosage of the reaction auxiliary agent III is 1.0 to 1.2 times the theoretical amount of the reaction between the potassium element of the auxiliary agent and the aluminum element of the overhaul slag.

[0030] Specifically, the main chemical reactions in the III-stage heating and roasting are as follows:

[0031] K2CO3 + Al2O3 + 6SiO2 = K2O·Al2O3·6SiO2 + CO2 (10)

[0032] 2KHCO3 + Al2O3 + 6SiO2 = K2O·Al2O3·6SiO2 + H2O + 2CO2 (11)

[0033] Also provided is a calcium feldspar which is prepared by the method for preparing feldspar using overhaul slag of electrolytic aluminum as described above; in step 4), the reaction auxiliary agent III is composed of calcium carbonate and calcium bicarbonate, and the dosage of the reaction auxiliary agent III is 1.0 to 1.1 times the theoretical amount of the reaction between the calcium element of the auxiliary agent and the aluminum element of the overhaul slag.

[0034] Specifically, the main chemical reactions in the III-stage heating and roasting are as follows:

[0035] CaCO3 + Al2O3 + 2SiO2 = CaO·Al2O3·2SiO2 + CO2 (12)

[0036] Ca(HCO3)2 + Al2O3 + 2SiO2 = CaO·Al2O3·2SiO2 + H2O + 2CO2 (13)

[0037] In order to avoid excessive CO2 generation during the III-stage roasting, the addition amounts of sodium bicarbonate, potassium bicarbonate and calcium bicarbonate in the reaction auxiliary agent III should be reduced as much as possible; in order to accelerate the reaction rate, the auxiliary agent III can be slightly in excess; in line with the principles of energy conservation, carbon reduction and cost reduction, the reaction auxiliary agent should not be in excess too much, and a better dosage is 1.0 - 1.2 times.

[0038] The beneficial effects of the present invention are as follows: ①. The spent potlining of electrolytic aluminum is subjected to the first-stage roasting and heating treatment by adding a reaction assistant, effectively removing carbon particles, aluminum particles, cyanides, carbides, nitrides, and sodium carbonate compounds contained in the spent potlining. The formation of a porous structure and the evolution of gas make the spent potlining become porous, which is conducive to the entry of air, accelerating the oxidative decomposition of cyanides, carbides, and nitrides, and also facilitating the subsequent separation of fluorides. ②. Through the second-stage heating and roasting treatment, it promotes the melting and aggregation of the assistant and fluorides, destroys the original compound structure, is conducive to the separation of fluorides and dross. All fluorides enter the molten salt, and the main components of the obtained dross are alumina and silica, which are used as raw materials for preparing feldspar. ③. The feldspar prepared through the third-stage heating and roasting has high product purity and more effectively avoids the pollution of fluorides to subsequent downstream products (such as glass and ceramics). BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is the XRD pattern of albite obtained in Example 1 of the present invention;

[0040] Figure 2 is the XRD pattern of orthoclase obtained in Example 2 of the present invention;

[0041] Figure 3 is the XRD pattern of anorthite obtained in Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The experimental methods without specific conditions in the following embodiments are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise specified, all percentages, ratios, proportions, or parts are by weight.

[0044] Example 1

[0045] A method for preparing albite using the spent potlining of electrolytic aluminum includes the following steps:

[0046] Step 1) The massive spent potlining of electrolytic aluminum is crushed, ground, sieved, and homogenized using a crusher to obtain aluminum electrolysis spent potlining powder with a particle size of 2 mm;

[0047] Step 2) Add 1000 g of aluminum electrolysis overhaul slag powder and 0.07 times of reaction assistant I (49 g of starch and 21 g of stearic acid) for mixing. After mixing evenly, the obtained mixed material A is placed in a furnace for the first-stage heating and roasting. The roasting temperature is 700 °C, and the roasting time is 1.0 h, obtaining 987.6 g of overhaul slag clinker E (testing its fluoride content is 30.3%);

[0048] Step 3) Mix 987.6 g of the overhaul slag clinker E obtained in Step 2 with 0.3 times of reaction assistant II (204 g of sodium chloride and 92.3 g of potassium chloride). After mixing evenly, the obtained mixed material B is placed in a furnace for the second-stage heating and roasting. The roasting temperature is 1000 °C, and the roasting time is 1 h, obtaining 687.6 g of dross F and 596.3 g of molten salt H;

[0049] Step 4) Grind the dross F obtained in Step 3, add 1.0 times of reaction assistant III (400 g of sodium carbonate and 45.5 g of sodium bicarbonate), and at the same time add 1181 g of silica, mix evenly to obtain mixed material C. The obtained mixed material C is placed in a furnace for the third-stage heating and roasting. The roasting temperature is 1100 °C, and the time is 2 h, obtaining 2119.4 g of crude feldspar. After washing and drying, 2118 g of albite is obtained. The XRD pattern of this albite is shown in Figure 1 , and the quality of the obtained albite meets the requirements of JC / T859 - 2000.

[0050] Example 2

[0051] A method for preparing potassium feldspar from electrolytic aluminum overhaul slag, comprising the following steps:

[0052] Step 1) Crush, grind, screen, and homogenize the massive electrolytic aluminum overhaul slag using a crusher to obtain aluminum electrolysis overhaul slag powder with a particle size of 2 mm;

[0053] Step 2) Add 1000 g of aluminum electrolysis overhaul slag powder and 0.03 times of reaction assistant I (15 g of starch and 15 g of stearic acid) for mixing. After mixing evenly, the obtained mixed material A is placed in a furnace for the first-stage heating and roasting. The roasting temperature is 600 °C, and the roasting time is 1.5 h, obtaining 982.6 g of overhaul slag clinker E (testing its fluoride content is 25.0%);

[0054] Step 3) Mix 982.6 g of the overhaul slag clinker E obtained in Step 2 with 0.5 times of reaction assistant II (245 g of sodium chloride and 246. / g of potassium chloride). After mixing evenly, the obtained mixed material B is placed in a furnace for the second-stage heating and roasting. The roasting temperature is 900 °C, and the roasting time is 2 h, obtaining 732.6 g of dross F and 741.3 g of molten salt H;

[0055] Step 4) Grind the scum F obtained in step 3), add 1.0 reaction aid III (530 g of potassium carbonate and 93.8 g of potassium bicarbonate), and at the same time add 1258.3 g of silica and mix evenly to obtain a mixed material C. Place the obtained mixed material C in a furnace for stage III heating and roasting at a roasting temperature of 1000 °C for 3 h to obtain 2396 g of crude feldspar. After washing and drying, 2393.5 g of potassium feldspar is obtained. The XRD pattern of this potassium feldspar is shown in Figure 2 , and the quality of the obtained potassium feldspar meets the requirements of JC / T859-2000.

[0056] Example 3

[0057] A method for preparing anorthite using spent potlining of electrolytic aluminum, comprising the following steps:

[0058] Step 1) Crush, grind, screen and homogenize the massive spent potlining of electrolytic aluminum using a crusher to obtain aluminum electrolysis spent potlining powder with a particle size of 2 mm;

[0059] Step 2) Add 1000 g of aluminum electrolysis spent potlining powder and 0.01 times of reaction aid I (3 g of starch and 7 g of stearic acid) for mixing. After mixing evenly, place the obtained mixed material A in a furnace for stage I heating and roasting at a roasting temperature of 500 °C for 2.0 h to obtain 977.6 g of spent potlining clinker E (test its fluoride content to be 27.3%);

[0060] Step 3) Mix 977.6 g of the spent potlining clinker E obtained in step 2) with 0.7 times of reaction aid II (205.3 g of sodium chloride and 479 g of potassium chloride). After mixing evenly, place the obtained mixed material B in a furnace for stage II heating and roasting at a roasting temperature of 800 °C for 3 h to obtain 704.6 g of scum F and 957.3 g of molten salt;

[0061] Step 4) Grind the scum F obtained in step 3), add 1.0 times of reaction aid III (360 g of calcium carbonate and 88.3 g of calcium bicarbonate), and at the same time add 208.5 g of silica and mix evenly to obtain a mixed material C. Place the obtained mixed material C in a furnace for stage III heating and roasting at a roasting temperature of 900 °C for 4 h to obtain 1152.2 g of crude anorthite. After washing and drying, 1151 g of anorthite is obtained. The XRD pattern of this anorthite is shown in Figure 3 , and the quality of the obtained anorthite meets the requirements of JC / T859-2000.

[0062] Example 4

[0063] A method for preparing albite using spent potlining of electrolytic aluminum, comprising the following steps:

[0064] Step 1) Crush, grind, screen, and homogenize the massive electrolytic aluminum overhaul slag using a crusher to obtain aluminum electrolytic overhaul slag powder with a particle size of 2 mm.

[0065] Step 2) Add 1000 g of aluminum electrolytic overhaul slag powder and 0.07 times of reaction auxiliary I (49 g of starch and 21 g of stearic acid) for mixing. After mixing evenly, the obtained mixed material A is placed in a furnace for section I heating and roasting. The roasting temperature is 700 °C, and the roasting time is 1.0 h to obtain 987.6 g of overhaul slag clinker E (testing its fluoride content is 30.3%).

[0066] Step 3) Mix 987.6 g of the overhaul slag clinker E obtained in Step 2 with 0.3 times of reaction auxiliary II (204 g of sodium chloride and 92.3 g of potassium chloride). After mixing evenly, the obtained mixed material B is placed in a furnace for section II heating and roasting. The roasting temperature is 1000 °C, and the roasting time is 1 h to obtain 687.6 g of dross F and 596.3 g of molten salt H.

[0067] Step 4) Grind the dross F obtained in Step 3, add 1.2 times of reaction auxiliary III (500 g of sodium carbonate and 23.0 g of sodium bicarbonate), and at the same time add 1181 g of silica. Mix evenly to obtain mixed material C. The obtained mixed material C is placed in a furnace for section III heating and roasting. The roasting temperature is 1100 °C, and the time is 1.5 h to obtain 2205.2 g of crude feldspar. After washing and drying, 2119 g of albite is obtained. The XRD pattern of the albite is shown in Figure 1 , and the quality of the obtained albite meets the requirements of JC / T859 - 2000.

[0068] The difference between Example 4 and Example 1 is that the dosage of auxiliary III is increased (from 1.0 times to 1.2 times). Under the same roasting temperature conditions, the reaction rate can be accelerated and the reaction time can be shortened. The achieved effects are: the reaction time is shortened from 2 h to 1.5 h, and the energy consumption of section III roasting is reduced by about 25%.

[0069] Example 5

[0070] A method for preparing potassium feldspar using electrolytic aluminum overhaul slag, comprising the following steps:

[0071] Step 1) Crush, grind, screen, and homogenize the massive electrolytic aluminum overhaul slag using a crusher to obtain aluminum electrolytic overhaul slag powder with a particle size of 2 mm.

[0072] Step 2) Add 1000 g of aluminum electrolytic overhaul slag powder and 0.03 times of reaction auxiliary I (15 g of starch and 15 g of stearic acid) for mixing. After mixing evenly, the obtained mixed material A is placed in a furnace for section I heating and roasting. The roasting temperature is 600 °C, and the roasting time is 1.5 h to obtain 982.6 g of overhaul slag clinker E (testing its fluoride content is 25.0%).

[0073] Step 3) Mix 982.6 g of the overhaul slag clinker E obtained in Step 2) with 0.5 times of reaction auxiliary II (245 g of sodium chloride and 246.3 g of potassium chloride). After mixing evenly, the obtained mixed material B is placed in a furnace for the second-stage heating and roasting. The roasting temperature is 900 °C, and the roasting time is 2 h, obtaining 732.6 g of floating slag F and 741.3 g of molten salt H;

[0074] Step 4) Grind the floating slag F obtained in Step 3), add 1.2 times of reaction auxiliary III (680 g of potassium carbonate and 48.7 g of potassium bicarbonate), and at the same time add 1258.3 g of silica and mix evenly to obtain a mixed material C. The obtained mixed material C is placed in a furnace for the third-stage heating and roasting. The roasting temperature is 1000 °C, and the time is 2.4 h, obtaining 2515 g of crude feldspar. After washing and drying, 2396 g of potassium feldspar is obtained. The XRD pattern of this potassium feldspar is similar to that of Example 2 (with a slight difference in the peak height), and the quality of the obtained potassium feldspar meets the requirements of JC / T859-2000.

[0075] The difference between Example 5 and Example 2 is that, under the condition of keeping other process parameters unchanged, the dosage of auxiliary III is increased (from 1.0 times to 1.2 times). Under the same roasting temperature condition, the reaction rate can be accelerated and the reaction time can be shortened. The achieved effects are: the reaction time is reduced from 3 h to 2.4 h, and the energy consumption of the third-stage roasting is reduced by about 20%.

[0076] Example 6

[0077] A method for preparing anorthite from electrolytic aluminum overhaul slag, comprising the following steps:

[0078] Step 1) Crush, grind, screen, and homogenize the massive electrolytic aluminum overhaul slag with a crusher to obtain aluminum electrolysis overhaul slag powder with a particle size of 2 mm;

[0079] Step 2) Add 1000 g of aluminum electrolysis overhaul slag powder and 0.04 times of reaction auxiliary I (10 g of starch and 30 g of stearic acid) for mixing. After mixing evenly, the obtained mixed material A is placed in a furnace for the first-stage heating and roasting. The roasting temperature is 500 °C, and the roasting time is 1.6 h, obtaining 977.6 g of overhaul slag clinker E (testing its fluoride content is 27.3%);

[0080] Step 3) Mix 977.6 g of the overhaul slag clinker E obtained in Step 2) with 0.7 times of reaction auxiliary II (205.3 g of sodium chloride and 479 g of potassium chloride). After mixing evenly, the obtained mixed material B is placed in a furnace for the second-stage heating and roasting. The roasting temperature is 800 °C, and the roasting time is 3 h, obtaining 704.6 g of floating slag F and 957.3 g of molten salt;

[0081] Step 4) Grind the scum F obtained in step 3), add 1.0 times of reaction aid III (360 g of calcium carbonate and 88.3 g of calcium bicarbonate), and at the same time add 215.5 g of silica and mix evenly to obtain a mixed material C. Place the obtained mixed material C in a furnace for stage III heating and roasting. The roasting temperature is 900 °C and the time is 4 h to obtain 1152.2 g of crude feldspar. After washing and drying, 1151 g of anorthite is obtained. The XRD pattern of this anorthite is shown in Figure 3 , and the quality of the obtained anorthite meets the requirements of JC / T859-2000.

[0082] The difference between Example 6 and Example 3 is that the dosage of additive I is increased (from 0.01 times to 0.06 times). Under the condition that other process parameters remain unchanged, increasing the dosage of additive I can accelerate the reaction rate, shorten the roasting time, save energy and reduce carbon emissions. The effects are as follows: the reaction time of stage I roasting is shortened from 2 h to 1.6 h, and the roasting energy consumption is reduced by about 20%;

[0083] The change in the dosage of additive I (2% / 4% / 6% / 8%, that is, 0.02 / 0.04 / 0.06 / 0.08 times) has little effect on the anorthite product; compared with not adding additive I (0%), the product has less impurities and is purer. This is because the main function of additive 1 is catalytic combustion, promoting the rapid decomposition of cyanides, carbides, nitrides, and sodium carbonate compounds, and avoiding the pollution of these compounds to subsequent products.

[0084] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing feldspar using overhaul slag from electrolytic aluminum and the feldspar prepared thereby, characterized in that, It includes the following steps: Step 1) Crush, grind, screen, and homogenize the massive electrolytic aluminum overhaul slag using a crusher to obtain electrolytic aluminum overhaul slag powder with particles ≤ 2 mm; Step 2) Mix the electrolytic aluminum overhaul slag powder with reaction auxiliary I. After mixing evenly, the obtained mixed material A is placed in a furnace for section I heating and roasting. The roasting temperature is 500 - 700 °C, and the roasting time is 1 - 2 h to obtain overhaul slag clinker E; Step 3) Mix the overhaul slag clinker E obtained in step 2) with reaction auxiliary II. After mixing evenly, the obtained mixed material B is placed in a furnace for section II heating and roasting. The roasting temperature is 800 - 1000 °C, and the roasting time is 1 - 3 h to obtain dross F and molten salt H; Step 4) Grind the dross F obtained in step 3), add reaction auxiliary III and mix evenly to obtain mixed material C. The obtained mixed material C is placed in a furnace for section III heating and roasting. The roasting temperature is 900 - 1100 °C, and the time is 2 - 4 h to obtain feldspar; Among them, in step 2), the reaction auxiliary I is composed of starch and stearic acid; In step 3), the reaction auxiliary II is composed of sodium chloride and potassium chloride; In step 4), the reaction auxiliary III is composed of carbonate and bicarbonate; 2. The method for preparing feldspar from spent potlining of electrolytic aluminum according to claim 1, characterized in that, In step 2), the addition amount of the reaction auxiliary I is 0.01 - 0.07 times the mass of the electrolytic aluminum overhaul slag powder; 3. The method for preparing feldspar from spent potlining of electrolytic aluminum according to claim 2, characterized in that, In step 2), the reaction auxiliary I is composed of starch and stearic acid, and the addition amount of the reaction auxiliary I is 0.02 - 0.06 times the mass of the electrolytic aluminum overhaul slag powder; 4. The method for preparing feldspar by using overhaul slag of electrolytic aluminum according to claim 1, characterized in that In step 3), the addition amount of the reaction auxiliary II is 0.3 - 0.7 times the mass of the overhaul slag clinker E; 5. The method for preparing feldspar using spent potlining from electrolytic aluminum according to claim 4, characterized in that In step 3), the reaction auxiliary II is composed of sodium chloride and potassium chloride, and the addition amount of the reaction auxiliary II is 0.4 - 0.6 times the mass of the overhaul slag clinker E; 6. A albite, characterized in that, This albite is prepared by the method for preparing feldspar using electrolytic aluminum overhaul slag according to any one of claims 1 - 5; in step 4), the reaction auxiliary III is composed of sodium carbonate and sodium bicarbonate, and the dosage of the reaction auxiliary III is 1.0 - 1.2 times the theoretical amount of the reaction between the sodium element of the auxiliary and the aluminum element of the overhaul slag; 7. A potassium feldspar, characterized in that, This orthoclase is prepared by the method for preparing feldspar using electrolytic aluminum overhaul slag according to any one of claims 1 - 5; in step 4), the reaction auxiliary III is composed of potassium carbonate and potassium bicarbonate, and the dosage of the reaction auxiliary III is 1.0 - 1.2 times the theoretical amount of the reaction between the potassium element of the auxiliary and the aluminum element of the overhaul slag; 8. A plagioclase, characterized in that, This anorthite is prepared by the method for preparing feldspar using electrolytic aluminum overhaul slag according to any one of claims 1 - 5; in step 4), the reaction auxiliary III is composed of calcium carbonate and calcium bicarbonate, and the dosage of the reaction auxiliary III is 1.0 - 1.1 times the theoretical amount of the reaction between the calcium element of the auxiliary and the aluminum element of the overhaul slag;

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