Method for treating high-iron red mud by dealkalizing calcium sucrose and synchronously reducing and extracting iron

Abstract

The invention relates to a method for treating high-iron red mud by synchronously dealkalizing sucrose calcium and synchronously reducing and extracting iron, which comprises the following process steps of: (1) putting sucrose and calcium oxide into a beaker, adding deionized water, uniformly mixing, keeping the temperature and heating for 1.5 hours in a water bath kettle at the temperature of 70 DEG C and the speed of 420 r / min, and complexing the sucrose and Ca (OH) 2 to form sucrose calcium salt; (2) preparing a reaction solution from the sucrose calcium solution and quantified red mud, putting the reaction solution into an alkaline high-pressure reaction kettle, and reacting for 60 minutes under the conditions of 240 DEG C and 420 r / min; (3) a dealkalized reduction solution and dealkalized tailings are obtained, a solution sample tube is reserved, and the dealkalized tailings are ground and smashed; (4) the dealkalized tailings are subjected to magnetic separation to obtain iron ore concentrate and tailings, and after suction filtration and drying, the iron ore concentrate is subjected to grinding and magnetic separation to obtain iron ore concentrate and tailings; and (5) adjusting parameters of the iron ore concentrate under magnetic separation to improve the iron extraction rate. The utilization rate of the red mud is 100%, and the dealkalization rate and the extraction rate of sodium alkali and iron are 90% or above and 40% or above respectively.

Description

Technical Field

[0001] The invention relates to the field of environmental protection, and in particular to a method for dealkalization, iron extraction and harmless treatment of high-iron red mud. Background Art

[0002] In the industrial process of extracting alumina from bauxite using the Bayer process, a special solid waste, red mud, is produced. This substance is bright reddish brown due to its significant iron content, and its appearance resembles red soil in nature, hence its name. The pH value of red mud is 10-13, and its high sodium content and strong alkalinity make red mud corrosive. In the production process of alumina, the production of red mud is an inevitable by-product. For every ton of alumina produced, 0.8-1.5 tons of red mud will be produced accordingly, which is an important environmental and resource management issue. Due to the production raw materials and production methods, its high pH value will cause serious pollution to open-air soil and water bodies. Red mud contains a variety of heavy metals, such as iron, aluminum, sodium, etc. These heavy metals can be washed into groundwater or rivers through rainwater, posing a threat to human health and the ecological environment. The storage of red mud will destroy the natural landscape and ecosystem, and affect biodiversity. The alkaline substances in red mud may cause salinization of the surrounding soil, affecting soil fertility and crop growth. The key to solving the red mud problem is to develop comprehensive red mud utilization technology.

[0003] In order to achieve efficient utilization of red mud and extraction of valuable elements, my country's aluminum industry has carried out a lot of research and development work. The existing red mud utilization technology can generally be divided into two types: one is to use it as a general industrial raw material as a whole, such as the "A method for preparing magnesium phosphate cement using low-grade magnesium phosphate materials using the salt lake method" invented by Pei Yan et al., application number: CN202410707471.X. The mixed liquid formed by polyacrylamide powder, acetone, and polysiloxane powder is heat-treated, and then the solid product is ground to obtain a modified silicone defoamer, the alkali solution and red mud powder are mixed and heated to react, and then a water-soluble carbonate is added and allowed to stand. After completion, the supernatant is taken to obtain a modified alkali-activated solution, and the modified silicone defoamer, modified alkali-activated solution, sodium stearate solution, low-grade magnesium phosphate material, retarder, kaolin, illite powder, sodium chloride, sodium aluminate, and water are taken. The above raw materials are mixed evenly to obtain magnesium phosphate cement; "A light ceramic brick with red mud as the base material, production process and application, application number: CN202410592531.8" invented by Zhong Lusheng et al. is calculated by mass percentage. The first raw material includes 50-84% red mud, 4-20% clay, 8-15% silicon powder and 4-15% potassium feldspar. The second raw material is foamed ceramic crushed material, and the third raw material is a foaming agent. The mass ratio of the second raw material to the first raw material is (0.15-0.3):1, and the mass ratio of the third raw material to the first raw material is (0.001-0.002):1. Red mud is the main base material to produce lightweight ceramic bricks that do not crack or deform and have a certain water absorption capacity, which is conducive to the recycling of red mud.

[0004] The other is to extract valuable metal elements such as V, Ga, Fe, and rare metals from red mud. Li Ke et al. invented a method for extracting silicon and multi-metal products from activated red mud, application number: CN201810572642.7. The red mud, coal gangue, and calcium carbonate are mixed evenly in proportion; the mixed material is crushed and ground, and then hot roasted and activated; the activated material is further ground; the ground material is magnetically separated, and then the non-magnetic slag is acid-dissolved; the acid-dissolved material is solid-liquid separated to obtain a mixed solution of white carbon black solid and multi-metal ions; the multi-metal ion mixture is The solution is separated in steps by controlling the pH value to obtain multiple metal products; the "Method for efficiently reducing high-speed iron red mud to extract metallic iron in an electric furnace, application number CN202410445513.7" invented by Meng Zhengbing et al. carbonizes the high-speed iron red mud to make balls. After the scrap steel is smelted into high-temperature molten steel in an electric furnace, the carbonized high-speed iron red mud balls are added to the molten steel in batches to quickly reduce the iron in the high-speed iron red mud and separate the slag from the iron, so that the reduced metallic iron is integrated into the molten steel, thereby effectively recovering the iron in the red mud.

[0005] When red mud is used as a general industrial raw material, there are problems such as red mud alkalinity restriction, low product price, and poor returns; the methods of extracting valuable elements separately mostly have problems such as too long processing flow, large amount of wastewater, and tailings that cannot be used. Therefore, although there are many studies on the utilization of red mud in the alumina industry, the current red mud storage problem has not been properly solved. Summary of the invention

[0006] In order to better realize the comprehensive utilization of red mud, the present invention provides a method for treating high-iron red mud by simultaneous reduction and iron extraction by sucrose calcium dealkalization, that is, using high-iron red mud, sucrose, and calcium oxide as raw materials, after sucrose calcium dealkalization and iron reduction, the dealkalized slag is directly converted into iron concentrate by adjusting parameters under magnetic separation conditions. The technical solution of the present invention is implemented according to the following steps:

[0007] (1) Put sucrose and calcium oxide into a beaker, add deionized water and mix evenly to make sucrose and Ca(OH)2 complex to form sucrose calcium salt;

[0008] The main reaction of sucrose calcium complexation is as follows:

[0009] CaO+H2O+C 12 H 22 O 11 →C 12 H 22 O 11 ·Ca(OH)2 (1)

[0010] (2) The sucrose calcium solution and the quantitative red mud were prepared into a reaction solution and placed in an alkaline high-pressure reactor for reaction at 240°C and 420 r / min for 60 min;

[0011] The main reaction of sucrose calcium dealkalization and simultaneous iron reduction to treat high-iron red mud is as follows:

[0012] Na2O・Al2Oз・xSiO2·(6-2x)H2O +3Ca 2+ +4OH - →3CaO·Al2O3 ·xSiO2 ·(6 - 2x)H2O + 2Na + +2H2O (2)

[0013] 3CaO·Al2Oз·xSiO2(6 - 2x)H2O +(3- 2x)CO2=xCaSiO4 +(3- 2x)CaCO3 + 2Al(OH)з + (3 - 2x)H2O (3)

[0014] Fe2O3+2OH - = 2FeO2 -+H2O (4)

[0015] 3FeO2 - +H·(R-CHO)+H2O = Fe3O4+3OH - (5)

[0016] (3) obtaining a dealkalizing reduction solution and dealkalizing tailings, retaining a sample tube of the solution for extracting other metals, and grinding and pulverizing the dealkalizing tailings to obtain a coarse material for magnetic separation;

[0017] (4) magnetically separating the dealkalized tailings to obtain iron concentrate and tailings, and grinding and magnetically separating the iron concentrate after filtration and drying to obtain iron concentrate and tailings;

[0018] (5) Adjust the magnetic intensity and parameters of iron concentrate under magnetic separation to improve the iron extraction rate and other metal behavior trends.

[0019] Compared with the prior art, the characteristics and beneficial effects of the present invention are:

[0020] (1) Sucrose and calcium oxide are used to synthesize sucrose calcium, which not only provides reducing substances for the subsequent iron extraction from red mud, but also provides calcium ion replacement for red mud dealkalization, which can comprehensively dealkalize and reduce iron;

[0021] (2) The Na2O content of high-iron red mud treated by sucrose calcium dealkalization and simultaneous reduction for iron extraction is below 1%. The tailings obtained from high-iron red mud are mainly composed of magnetite, which can better meet the composition requirements of magnetic separation for iron extraction;

[0022] (3) Calcium de-alkalization and simultaneous reduction and iron extraction of sucrose. While calcium ions replace sodium ions, the reducing substances in sucrose also simultaneously reduce Fe2O3. The process is completed in one step without the need to create additional reducing conditions.

[0023] (4) The dealkalized tailings can be directly converted into crude iron ore raw materials after drying, crushing and grinding. While extracting iron, the alkali-free tailings can be fully used in other scenarios, and the red mud utilization rate reaches 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process flow of the present invention: DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the embodiments.

[0026] Example 1

[0027] The TFe content of the raw material high iron red mud is 43%.

[0028] (1) Take 100g of high-iron red mud as the base raw material, weigh 40g of calcium oxide and 25g of sucrose, and add an appropriate amount of deionized water to the beaker to ensure that all substances are fully dissolved and mixed. After that, the beaker containing the calcium oxide and sucrose mixture is placed in a water bath set at a constant temperature of 70°C and stirred at a speed of 420 r / min to promote the uniformity and efficiency of the reaction. Under such mild conditions, the reaction lasted for 1.5 hours, resulting in a close complexation between sucrose and Ca(OH)2, and finally forming the desired sucrose calcium solution.

[0029] (2) The prepared calcium sucrose solution was mixed with a certain amount of red mud to form a reaction solution, which was then added to an alkaline autoclave and reacted for 60 min at 240 °C and 420 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid, and the filter residue was dried and placed in a sealed bag for later use.

[0030] (3) Grinding the dried red mud for 20 min with a particle size of 100 mesh;

[0031] (4) The controlled variable method is used to perform multiple magnetic separations under the conditions of 10 min magnetic separation time and 0.1 T magnetic separation intensity, and then the magnetically separated iron concentrate and tailings are ground and magnetically separated again;

[0032] (5) After grinding, the red mud after magnetic separation had a dealkalization rate of 92%, and the contents of Fe3O4, CaO, SiO2, and K2O were 52.64%, 16.95%, 2.88%, and 0.56%, respectively.

[0033] Example 2

[0034] The TFe content of the raw material high iron red mud is 22%.

[0035] (1) Take 100g of high-iron red mud as the base raw material, weigh 40g of calcium oxide and 25g of sucrose, and add an appropriate amount of deionized water to the beaker to ensure that all substances are fully dissolved and mixed. After that, the beaker containing the calcium oxide and sucrose mixture is placed in a water bath set at a constant temperature of 70°C and stirred at a speed of 420 r / min to promote the uniformity and efficiency of the reaction. Under such mild conditions, the reaction lasted for 1.5 hours, resulting in a close complexation between sucrose and Ca(OH)2, and finally forming the desired sucrose calcium solution.

[0036] (2) The prepared calcium sucrose solution was mixed with a certain amount of red mud to form a reaction solution, which was then added to an alkaline autoclave and reacted for 60 min at 240 °C and 420 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid, and the filter residue was dried and placed in a sealed bag for later use.

[0037] (3) Grinding the dried red mud for 10 min with a particle size of 200 mesh;

[0038] (4) The control variable method is used to perform multiple magnetic separations under the conditions of 20 min magnetic separation time and 0.3 T magnetic separation intensity, and then grind the magnetically separated iron ore and tailings and then perform magnetic separation again.

[0039] (5) After grinding, the red mud after magnetic separation had a dealkalization rate of 93%, and the contents of Fe3O4, CaO, SiO2, and K2O were 42.23%, 8.62%, 2.33%, and 0.36%, respectively.

[0040] Example 3

[0041] The raw material high iron red mud TFe content is 50%.

[0042] (1) Take 100g of high-iron red mud as the base raw material, weigh 40g of calcium oxide and 25g of sucrose, and add an appropriate amount of deionized water to the beaker to ensure that all substances are fully dissolved and mixed. After that, the beaker containing the calcium oxide and sucrose mixture is placed in a water bath set at a constant temperature of 70°C and stirred at a speed of 420 r / min to promote the uniformity and efficiency of the reaction. Under such mild conditions, the reaction lasted for 1.5 hours, resulting in a close complexation between sucrose and Ca(OH)2, and finally forming the desired sucrose calcium solution.

[0043] (2) The prepared calcium sucrose solution was mixed with a certain amount of red mud to form a reaction solution, which was then added to an alkaline autoclave and reacted for 60 min at 240 °C and 420 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid, and the filter residue was dried and placed in a sealed bag for later use.

[0044] (3) Grinding the dried red mud for 20 min with a particle size of 300 mesh;

[0045] (4) The control variable method is used to perform multiple magnetic separations under the conditions of 20 min magnetic separation time and 0.5 T magnetic separation intensity, and then grind the magnetically separated iron ore and tailings and then perform magnetic separation again.

[0046] (5) After grinding and magnetic separation, the dealkalization rate of red mud was 95%, and the contents of Fe3O4, CaO, SiO2, and K2O were 55.96%, 12.83%, 3.46%, and 0.087%, respectively.

Claims

1. A method for treating high-iron red mud by simultaneous reduction and iron extraction by sucrose calcium dealkalization, involving the utilization of high-iron red mud, It is characterized in that The following steps are involved: (1) Put sucrose and calcium oxide into a beaker, add deionized water and mix well. Heat in a water bath at 70 °C and 420 rpm for 1.5 h to allow sucrose and Ca(OH) 2 Complexation is performed to form sucrose calcium salt; (2) The sucrose calcium solution and the quantitative red mud were prepared into a reaction solution and placed in an alkaline high-pressure reactor for reaction at 240°C and 420 r / min for 60 min; (3) obtaining a dealkalizing reduction solution and dealkalizing tailings, retaining the solution sample tube, and grinding and crushing the dealkalizing tailings; (4) magnetically separating the dealkalized tailings to obtain iron concentrate and tailings, and grinding and magnetically separating the iron concentrate after filtration and drying to obtain iron concentrate and tailings; (5) Adjust parameters of iron concentrate under magnetic separation to improve iron extraction rate.

2. A method for treating high-iron red mud by simultaneous reduction and iron extraction by calcium sucrose dealkalization according to claim 1, Features The TFe content of high-iron red mud treated with sucrose calcium is 20%~55%, Ca / Si is 0.5~3, and Na 2 The O content is between 0.1% and 0.3%.

3. The method for treating high-iron red mud by simultaneous reduction and iron extraction by calcium sucrose dealkalization according to claim 1, Features Sucrose and calcium oxide were complexed to form sucrose calcium salt, and then the reaction solution was prepared together with the dehydrated red mud and put into an alkaline high-pressure reactor for dealkalization and synchronous reduction at 240°C and 420 r / min for 60 min.

4. The method for treating high-iron red mud by simultaneous reduction and iron extraction by calcium sucrose dealkalization according to claim 1, Features A dealkalizing reduction solution and dealkalizing tailings are obtained, the solution sample tube is retained, and the dealkalizing tailings are ground and pulverized for magnetic separation.

5. The method for treating high-iron red mud by simultaneous reduction and iron extraction by calcium sucrose dealkalization according to claim 1, Features The dealkalized tailings are subjected to magnetic separation to obtain iron concentrate and tailings, and the iron concentrate is directly obtained by magnetic separation; the tailings are treated without alkali and harmlessly.

6. The method for treating high-iron red mud by simultaneous reduction and iron extraction by calcium sucrose dealkalization according to claim 1, Features The magnetic intensity and parameters of iron concentrate are adjusted under magnetic separation to improve the iron extraction rate and other metal behavior trends.

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