阅读说明：本技术 赤泥资源回收与利用工艺 (Red mud resource recovery and utilization process ) 是由 许国勇 李发祥 董婷 于 2020-05-26 设计创作，主要内容包括：赤泥是制铝工业提取氧化铝时产生的废渣,因含有氧化铁而呈红色,固称赤泥。赤泥是氧化铝生产产生的最大废渣,给社会环境带来沉重的负担。生产企业依靠大面积的露天场所堆放,并且大部分堆场坝体用赤泥构筑而成。赤泥中许多可利用成分还未得到开发,造成资源浪费。随着铝工业的快速发展和矿石品位的降低,赤泥产出量会越来越大,因此赤泥的资源回收与利用,已成为日益主要的研究课题与方向。本发明的特征为,把赤泥置于旋转窑烧结,在600-700℃使铁的氧化物变为铁酸钠,水解后为氢氧化铁,用伯胺N-1923试剂除铁。回收氧化铝、镁、氯化钙,回收氯化钠,水回用。余渣磁选法回收四氧化三铁,余渣与煤矸石制砖。(Red mud is waste residue generated in the process of extracting aluminum oxide in the aluminum industry, is red due to the iron oxide, and is called red mud. The red mud is the largest waste residue generated in the production of alumina, and brings heavy burden to social environment. Production enterprises rely on large-area open-air places for stacking, and most of the dam bodies of the stacking fields are constructed by red mud. Many available components in the red mud are not developed yet, and resource waste is caused. With the rapid development of the aluminum industry and the reduction of ore grade, the red mud output will be larger and larger, so the recovery and utilization of red mud resources have become increasingly major research subjects and directions. The invention is characterized in that the red mud is sintered in a rotary kiln, iron oxide is changed into sodium ferrite at the temperature of 600-700 ℃, the sodium ferrite is hydrolyzed into ferric hydroxide, and the ferric hydroxide is removed by primary amine N-1923 reagent. And (3) recovering aluminum oxide, magnesium and calcium chloride, and recovering sodium chloride and recycling water. And (3) recycling ferroferric oxide by a residue magnetic separation method, and making bricks by using the residue and coal gangue.)

1. The red mud resource recovering and utilizing process is that high temperature rotary kiln roasting is adopted and water is added to prepare slurry based on the physical and chemical properties of red mud. Under alkaline condition, sodium ferrite is hydrolyzed into solution composed of ferric hydroxide, aluminum hydroxide, magnesium hydroxide, calcium chloride, sodium chloride and the like.

2. The method as claimed in claim 1, wherein the technical features are: and (3) carrying out filter pressing separation on the solution containing the metal ions, and adding primary amine N-1923 into the solution to serve as a directional iron remover. The feed ratio is Fe³⁺1:0.6 primary amine N-1923, namely 1mol of iron ion is compared with 0.6mol of primary amine reagent, the iron removal solution is used for precipitating aluminum hydroxide when the pH value is adjusted to 4.7-5.8 by hydrochloric acid (20 percent), and then the pH value is adjusted to about 10-11 to obtain the magnesium hydroxide. Sodium chloride is used as seed crystal, calcium and sodium chloride are recovered, and water is recycled.

3. The iron-containing concentrate is recovered from the red mud residue by a magnetic separation method and is less than or equal to 55 percent. The residual slag is added with 75:25(W/W) of coal gangue for mixed brick making, and the compressive strength of the brick body reaches 10-15MPa in the experiment.

One, the technical field

The red mud is industrial waste residue with high alkali content discharged in the production process of alumina. Because bauxite contains high iron, the residue looks like red mud, which is called red mud. Generally, the alumina yield increases at a rate of more than 20% per year per 1 ton of alumina to discharge 0.5-1.5 tons of red mud, and thus the red mud amount will increase. The total discharge amount of red mud in China is billions of tons, and the quantity is incredible.

At present, no suitable method exists for treating the red mud, and the red mud is mostly stacked by damming. The method not only occupies a large amount of land and consumes a large amount of capital to build a huge storage yard and pay high maintenance cost, but also pollutes the surrounding environment of the storage yard and an underground water system, seriously damages the natural ecological environment and restricts the development of the alumina industry.

The invention relates to red mud treatment, which belongs to the technical field of environment, and the research subjects are environmental science and technology, environmental engineering and solid pollutant control engineering.

Second, background Art

The red mud is industrial alkali-containing waste residue discharged in the production process of alumina, and mainly comprises aragonite and calcite, and secondly comprises diaspore, goethite, a small amount of siderite, water glass, sodium aluminate and caustic soda, wherein the content of aluminum oxide is 10-22%, and the content of ferric oxide is 7.5-38%. The red mud contains various recyclable metal oxides, which becomes the basis for the recycling of the red mud.

The secondary comprehensive utilization of red mud has been reported in many scientific researches at home and abroad. For example, iron and titanium are extracted from red mud, and the extracted red mud is used as a plastic additive or a silicon fertilizer to produce cement and other building materials, road building materials, mine filling materials and the like. However, the implementation is limited, and the reason is that the content of strong base in the red mud exceeds the standard, which seriously affects the bulk utilization of the red mud.

Foreign red mud treatment

Alumina factories in France, America, Japan, etc. are built by the sea and directly discharged to the sea. Australia is an alumina plant in Queensland and some alumina plants built near the coast in Western Australia, the red mud is washed by seawater by utilizing the advantage of sea approach, the pH value of the red mud is reduced to less than 10, and stacking is carried out, so that the seepage-proofing cost for building a red mud stacking yard can be reduced.

Reference to the literature

1. 1-Congly Y，Kiy,Erson M，Recovery and Concen Traction of AL(Ⅲ),Fe(Ⅲ),Ti(Ⅳ)，Na(I)From，red mud[J].Joural of Colloid and insteace Science,2001,24(2):342～346.

2.Mishra B,Stdey A.,Recovery of value added Products from red muf[J].Mincrals and Metallurgical procesrning.Society for cuiaing,Metalluny ang ECPlocation,2002，19(a2)：87～89.

Domestic red mud treatment

1. Preparation of baked brick

The red mud has fine granularity, soft quality and certain plasticity, and can replace clay to be used as a raw material for producing the baked bricks. The method consumes a large amount of red mud, does not need to add new equipment, and saves 70% of clay. But the mechanical degree in the brick making process is low, the alkalinity of workers contacting red mud is strong, and the workers are easy to cause damage to human bodies.

2. For cement production

The red mud also contains a large amount of calcium, which can replace part of raw materials to produce different varieties of cement. Because the alkali content of the red mud is high, the low alkali characteristic required by cement production cannot be achieved when the dosage of the red mud is too much. Meanwhile, the labor protection and the equipment use of workers are highly required, and the difficulty of the technology popularization is increased.

3. As roadbed material

The red mud is used as a novel road base material, has better freezing stability, drying shrinkage and temperature shrinkage, is a comprehensive utilization mode with larger consumption of the red mud, and can be used only after comprehensive curing technologies such as pressure-alkali stabilization, ion exchange, red mud activation, pressure forming and the like.

4. Recovery of iron

Most patents are that red mud is pre-roasted, then ferric oxide is reduced by a fluidized bed furnace at the temperature of 700 ℃ and 800 ℃ to be changed into ferroferric oxide, and then the ferroferric oxide is cooled, crushed and magnetically separated to finally obtain iron fine powder with the concentration of more than 63 percent. According to data statistics, the content of ferric oxide in foreign red mud is between 30 and 52 percent, and the content of ferric oxide in domestic red mud is between 7 and 39 percent, but the method requires that the content of iron in red mud is high, namely, the red mud only can be treated by Bayer process, and the red mud is difficult to be utilized by sintering process and combination process.

Reference to the literature

1. Wang culture: research on the production of baked bricks from industrial waste red mud [ J ]. masonry, 2006 (below): 42-43.

2. Liu Chun, Yi national gan: study on concrete production from red mud by sintering process [ J ]. comprehensive utilization of chinese resources, 2007, (3): 17-19.

3. Broad yang family, good health, good peach kernel, etc.: examples of engineering applications of sintering-process red mud road materials and economic analysis [ J ] light metals, 2007, (2):18-21

4. Huangzhu, Sun Zong Yi, left-language: the iron-containing red mud reduction and separation mechanism is discussed in J. 1992, (4): 23-29.

Third, the invention

According to the physical and chemical properties of the red mud, the red mud is roasted by a rotary furnace, then treated by acid leaching, and subjected to solid-liquid separation to obtain products such as aluminum hydroxide, iron, magnesium, calcium chloride, sodium and the like in solution in stages.

The experimental result shows that after the ore is roasted by water, slag and liquid are separated. The solution is treated with primary amine N-1923 for iron removal. The solution is adjusted in pH to obtain aluminum, magnesium, hydroxide and magnesium and sodium chloride. The dealkalized red mud can be completely used for making bricks, cement or paving base materials. The quality of various products reaches the corresponding industrial standard. The treatment cost is controllable, so that the red mud treatment has certain economic benefit.

Fourthly, the concrete implementation steps

The red mud obtained by different processes in the production of alumina has different chemical components and phase compositions. The red mud mineral components are measured by means of a polarizing microscope, a scanning electron microscope and the like, and the red mud mineral components are considered to mainly comprise aragonite and calcite, and then opal, diaspore, goethite, a small amount of titanium mineral, siderite, sodium aluminate and caustic alkali. The method adopts roasting and acid leaching modes to dissolve metal oxides in the red mud and eliminate the alkalinity of the red mud so as to obtain useful metal oxides, and the residual slag can be used as a treatment method of building materials, thereby being the key for solving the problems of recycling and utilizing red mud resources at present.