A kind of industrial high acid wastewater neutralizer and its preparation method and application

Abstract

The present invention relates to a kind of industrial high acid wastewater neutralizer and preparation method and application. The neutralizer composition includes oxygen, magnesium, iron, calcium, silicon, aluminum, etc., wherein the content of magnesium element accounts for 45% and above, the content of oxygen element accounts for more than 30%, and the content of iron, calcium, silicon and aluminum is respectively between 0.05-10%. The neutralizer of the present invention utilizes special wet calcination process and raw material formula to form a special crystal structure, has good internal pore structure and large specific surface area and small particle size, shows high acid neutralization activity, also shows the characteristics of strong activity maintenance ability in conventional environment, overcomes the conventional magnesium oxide neutralizer storage medium acid neutralization activity is more easily reduced deficiency. The neutralizer has a large contact area with wastewater, reacts more fully, is more active, can quickly react with acidic wastewater acid-base neutralization reaction and promotes heavy metal precipitation, therefore can be used in the treatment of industrial heavy metal sewage.

Description

Technical Field

[0001] The invention relates to the field of industrial highly acidic wastewater treatment, and in particular to an industrial highly acidic wastewater neutralizer and a preparation method and application thereof. Background Art

[0002] Acidic wastewater usually contains a large amount of acidic substances and heavy metal ions, which are very harmful to the environment and human health. If these wastewaters are discharged directly into the environment without treatment, they will cause soil and water acidification, destroy the ecological balance, and affect the survival of aquatic organisms and crops. At the same time, heavy metal ions such as lead and chromium are toxic, and long-term accumulation will pose a serious threat to human health.

[0003] At present, the treatment method for this type of wastewater is mainly based on direct neutralization, and common neutralizers include sodium hydroxide, calcium hydroxide, etc. The price of sodium hydroxide is relatively high, resulting in high treatment costs, and it is highly corrosive, has potential safety hazards in use, and has high requirements for storage equipment. Although the price of calcium hydroxide is relatively low, for the current situation in the industry where the anions of acidic wastewater are mainly sulfate, a large amount of calcium sulfate precipitation will be produced, and the sludge disposal cost is high. If it is not properly disposed of, it may cause secondary pollution to the environment; in addition, the newly generated calcium sulfate will wrap around the calcium hydroxide, preventing the calcium hydroxide from continuing to react, thereby reducing the utilization rate of the agent.

[0004] CN105107457A relates to a preparation method and application of an inorganic powder material, wherein an oxide or / and an oxide precursor is ground for the first time, then roasted, washed with water, and dried, and then ground for the second time after drying to obtain the inorganic powder material; the oxide can be selected from at least 3 of CaO, MgO, SiO2, Fe3O4, Fe2O3, Al2O3, etc., preferably a mixture of CaO, SiO2, Fe2O3 and Al2O3. The document discloses an inorganic material mainly composed of calcium oxide, and the large-scale use of calcium oxide will lead to a high degree of danger in use; at the same time, the calcination time in the preparation process is only 20 minutes, which cannot achieve the purpose of high activity.

[0005] Since magnesium oxide is economical to transport and easy to use, it is valued by the industry. CN1572730A relates to a neutralizer for treating acidic wastewater in cold rolling of the metallurgical industry, wherein the neutralizer for treating acidic wastewater is: light-burned magnesium powder sieved material crushed by Raymond mill to a particle size of 100-140 mesh, electro-melted magnesium dust removal ash, light-burned magnesium powder or magnesium-based materials with a content of more than 40%. The neutralizer used in the document has a large particle size and low reaction activity, and has the disadvantages of long reaction time and large mud production when treating acidic wastewater.

[0006] CN107456944A relates to an inorganic composite material, which is mainly prepared by the composite of limestone, magnesite, dolomite, brucite and apatite, and has a zeolite-like structure with a flaky particle size of 1 micron to 5000 microns and a specific surface area of ​​200-500m 2 / g. The preparation method of the comparative document does not control the particle size of the raw materials, and the purpose of high activity cannot be achieved under this process condition. At the same time, the preparation process is relatively complicated and the economic efficiency is average.

[0007] In the process of neutralizing acidic wastewater using a neutralizer containing magnesium oxide, it is usually necessary to first hydrate into magnesium hydroxide, and then ionize hydroxide to react with acids and heavy metals. The reaction process is relatively long and the newly hydrated magnesium hydroxide will adhere to the surface of magnesium oxide to prevent the hydration reaction, resulting in reduced reaction activity, low efficiency of reaction with acids and heavy metals, waste of reagents, high treatment costs and more sediment. Moisture absorption during powder storage and / or the formation of insoluble magnesium hydroxide or basic magnesium carbonate with carbon dioxide also reduce the maintenance of acid neutralization activity.

[0008] Therefore, it is necessary to explore a neutralizer for treating acidic industrial wastewater with stronger reactivity, more stable reactivity and better economic efficiency. Reducing the moisture absorption capacity of the surface of magnesium oxide and maintaining a suitable particle size (specific surface area) will help overcome the shortcomings of the above-mentioned prior art. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides an industrial high-acid wastewater neutralizer with high reaction activity, good economy and good storage stability and its preparation method and application through doping elements and preparation process control. The industrial high-acid wastewater neutralizer is an industrial high-acid wastewater neutralizer with high acid neutralization activity and high activity stability.

[0010] One object of the present invention is to provide an industrial highly acidic wastewater neutralizer, which is composed of 45-60% magnesium, 0.05-10% iron, 0.05-10% aluminum, 0.05-10% calcium, 0.05-10% silicon, and the remainder is oxygen, and the mass ratio of oxygen is more than 30%.

[0011] As a preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the neutralizer is in the form of powder.

[0012] As a preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, it is prepared by a wet calcination method. As a further preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, wet calcination is performed after ball milling. As a further preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the temperature is slowly lowered after wet calcination, preferably naturally lowered to room temperature.

[0013] As a preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the elements such as iron, aluminum, calcium, silicon and the like are present in the form of active silicates or active aluminates. Furthermore, it is preferred that aluminum and silicon are present in the form of active silicates or active aluminates.

[0014] As a further preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the magnesium content percentage is preferably 45-60%, further preferably 50-58%, and most preferably 52-56%. As a further preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the iron, aluminum, calcium and silicon content percentages are independently preferably 0.05-10%, further preferably 0.1-5%, and most preferably 1-3%.

[0015] As a preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, its particle size is 1-100 μm. As a further preferred embodiment, its particle size is 5-50 μm. The most preferred particle size is 15-35 μm.

[0016] As the preferred method of the above-mentioned industrial highly acidic wastewater neutralizer, its specific surface area is 5~2000m 2 As a further preferred neutralizer for industrial highly acidic wastewater, its specific surface area is 800-1500 m 2 / g, and preferably between 1000 and 1300 m 2 / g.

[0017] As a preferred embodiment of the above-mentioned industrial highly acidic wastewater neutralizer, the 180-day activity reduction value of the industrial highly acidic wastewater neutralizer is less than 10. The above-mentioned 180-day activity reduction value is the difference (∆ CAA ),∆ CAA =CAA 180 -CAA0, CAA0 represents the initial activity value after preparation (i.e., day 0), CAA 180 It indicates the activity value 180 days after preparation.

[0018] As a preferred mode of the above-mentioned industrial highly acidic wastewater neutralizer, it not only shows high acid neutralization activity, but also shows the characteristics of strong activity maintenance ability in a conventional environment.

[0019] As a preferred form of the above-mentioned industrial highly acidic wastewater neutralizer, its components exist in the form of forming A metal-oxygen-B metal bonds (for the convenience of description, the metalloid silicon element is also referred to as a metal here, wherein A and B are independently one of the metals in the present invention), including magnesium-oxygen bonds, iron-oxygen bonds, calcium-oxygen bonds, aluminum-oxygen bonds and silicon-oxygen bonds, as well as metal bonds formed between each other.

[0020] Another object of the present invention is to provide a method for preparing the industrial highly acidic wastewater neutralizer. The method comprises the following steps: (1) crushing and pulverizing raw materials containing magnesium; (2) crushing and pulverizing raw materials containing iron, aluminum, calcium and silicon alone or in combination; (3) fully mixing the powder materials obtained in steps (1) and (2) according to the element ratio, and adding water during the mixing process to form a uniform slurry between the materials; (4) directly calcining the water-containing slurry; (5) slowly cooling the calcined materials to room temperature and then sieving them to remove large particles to obtain the target product.

[0021] As a preferred embodiment of the above method, the crushing and pulverization is performed by ball milling. As a further preferred embodiment of the above method, the ball milling time is selected to be 10-90 minutes, preferably 30-60 minutes.

[0022] As a preferred embodiment of the above method, the powder particle size is 50-100 μm during crushing and pulverizing. The powder particle size of each raw material can be independently selected within the particle size range of the present invention when crushing and pulverizing different raw materials. As a further preferred embodiment of the above method, the powder particle size is 70-80 μm during crushing and pulverizing.

[0023] As a preferred embodiment of the above method, the raw material containing magnesium element can be natural or non-natural. As a further preferred embodiment, the raw material containing magnesium element is selected from one or more of magnesite, dolomite, magnesium hydroxide and magnesium carbonate.

[0024] As a preferred embodiment of the above method, the raw materials containing iron, aluminum, calcium and silicon elements are crushed and pulverized separately or mixed, that is, one or more of them are crushed and pulverized. Further preferably, the raw materials containing iron, aluminum, calcium and silicon elements are selected from one or more of nitrates, carbonates, basic carbonates, silicates, chlorides and hydroxides. The raw materials containing iron, aluminum, calcium and silicon elements may contain only one element selected from iron, aluminum, calcium and silicon, or may contain multiple elements selected from iron, aluminum, calcium and silicon. The raw materials containing iron, aluminum, calcium and silicon elements may be mixed and then crushed, or they may be crushed separately.

[0025] As a preferred embodiment of the above method, 10 to 500% of water by weight of the total powder material is added during the mixing process.

[0026] As a further preferred embodiment of the above method, 20-200% of water by weight of the total powder material is added during the mixing process.

[0027] As a preferred embodiment of the above method, the calcination temperature is 600 to 1200° C. As a further preferred embodiment of the above method, the calcination temperature is 800 to 950° C.

[0028] As a preferred embodiment of the above method, the calcination time is 1 to 3 hours. As a further preferred embodiment of the above method, the calcination time is 2 to 2.5 hours.

[0029] As a preferred embodiment of the above method, the mixture is sieved through 100-500 mesh after cooling. As a further preferred embodiment of the above method, the mixture is sieved through 200-325 mesh after cooling.

[0030] Another object of the present invention is to provide application of the industrial highly acidic wastewater neutralizer in treating industrial highly acidic wastewater.

[0031] As a preferred embodiment of the above application, the anions of the acidic wastewater are inorganic acid or organic acid radical ions, and more preferably sulfate, chloride, fluoride, phosphate, nitrate, and acetate.

[0032] As a preferred embodiment of the above application, the cations of the acidic wastewater are heavy metal ions. Furthermore, the heavy metal ions are selected from heavy metal ions that can be precipitated by alkalinity. More preferably, the heavy metal ions are selected from one or more of nickel, chromium, cadmium, lead, iron, copper, and zinc.

[0033] As used herein, the data of the present invention are interpreted as follows:

[0034] In the industrial highly acidic wastewater neutralizer of the present invention, the magnesium content percentage (data unit is %) can be 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 59.8, and 60.

[0035] In the industrial highly acidic wastewater neutralizer of the present invention, the percentage contents of iron, aluminum, calcium and silicon (data unit is %) are independently 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10.

[0036] The particle size (in μm) of the industrial highly acidic wastewater neutralizer of the present invention can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100.

[0037] The specific surface area (data unit is m 21400, 1450, 1500, 1600, 1700, 1800, 1900, 2000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 8500, 9000, 9500, 10000, 10500, 11000, 11500, 12000, 12500, 13000, 1350, 14000, 14500, 15000, 16000, 17000, 18000, 19000, 20000.

[0038] During the crushing and pulverization of the present invention, the powder particle size (data unit is μm) reaches 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100.

[0039] During the crushing and pulverizing process of the present invention, the ball milling time (data unit is min) is 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90.

[0040] In the mixing process of the present invention, the amount of water added is 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500 of the total weight of the powder material.

[0041] During the calcination of the present invention, the calcination temperature (data unit is ℃) is 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200.

[0042] During the calcination of the present invention, the calcination time (data unit is h, i.e. hours) is 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3.

[0043] When sieving after cooling according to the present invention, the sieving (data unit is mesh) is 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, and 500.

[0044] The industrial high-acid wastewater neutralizer of the present invention will form hydroxides such as magnesium hydroxide, iron hydroxide, calcium hydroxide, aluminum hydroxide, etc. after contacting with water, and then ionize hydroxide to react with hydrogen ions and metal ions. Compared with directly using hydroxides, the consumption of reagents and the amount of precipitates generated can be reduced, thereby reducing the cost of wastewater treatment.

[0045] The present invention adopts a special raw material formula and preparation process to achieve the purpose of high and stable product activity. In the preparation process of the present invention, different raw materials are crushed to increase their specific surface area, which is helpful for subsequent slurry mixing; in the mixing process in the slurry state, the inorganic matter in the raw materials will be partially hydrated, and the inorganic salts of different components will form a closer combination form through the "bridge" effect of water molecules; in the subsequent calcination process, water evaporates in the form of gas at high temperature, so that the calcined powder forms a large number of pores at the microscopic level; at the same time, during the calcination process, iron, silicon, calcium and aluminum can form a new crystal structure with magnesium through the connection of oxygen atoms, wherein the presence of silicon and aluminum elements can improve the surface stability of the crystal, and the presence of iron and calcium elements can accelerate the reaction rate of the crystal in acidic wastewater. The industrial high-acid wastewater neutralizer prepared by the present invention has the characteristics of developed internal structure pores, small particle size, large specific surface area, and high storage stability. It has a large contact area with acidic wastewater, so the neutralization reaction speed is fast and the reaction is more sufficient, and it can quickly and effectively neutralize the acidic substances in the wastewater and promote the precipitation of heavy metals. It can be seen that the industrial highly acidic wastewater neutralizer prepared by the present invention has the characteristics of high acid neutralization activity and good activity stability.

[0046] Due to the adoption of the above technical solution, the present invention has at least the following beneficial effects:

[0047] (1) The porous structure formed by the mixed slurry of magnesium, iron, silicon, aluminum and calcium during the wet calcination process is relatively developed. These porous structures greatly increase the reaction activity and activity stability of the product. The reaction activity of the product of the present invention is 50% higher than that of the dry calcination product, and the activity stability is increased by 90%.

[0048] (2) The industrial highly acidic wastewater neutralizer product of the present invention within the particle size range has a very large specific surface area and can be quickly decomposed in acid water to play a neutralizing role. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is the particle size distribution diagram of the product of Example 1 of the present invention.

[0050] Figure 2 This is the XRD diagram of the product of Example 1 of the present invention.

[0051] Figure 3 This is a scanning electron microscope image of the product of Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0053] The sources of the following materials are shown in Table 1:

[0054] Table 1 Source of materials

[0055]

[0056] Embodiment 1:

[0057] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen, and includes the following steps:

[0058] (1) 88.75 parts of magnesia powder (containing silicon), 3.75 parts of calcium hydroxide, 3.75 parts of ferric hydroxide, and 3.75 parts of aluminum hydroxide, wherein each material is ball-milled for 30 minutes to make the powder particle size reach 50 μm, (2) 30 parts of water are added to the above materials after mixing, and stirred into slurry, (3) the slurry is calcined in a converter at 900°C for 1 hour, and (4) the calcined material is passed through a 325 mesh sieve. The particle size (D50) of the powder prepared in this embodiment is 11.8 μm, and the specific surface area is 1238 m 2 / g.

[0059] The particle size distribution of the product is shown in Figure 1 As shown, the XRD pattern is Figure 2 As shown in the scanning electron microscope image Figure 3 The particle size (D10) of the powder is 1.964μm, the particle size (D25) is 3.565μm, the particle size (D50) is 11.801μm, the particle size (D75) is 40.835μm, the particle size (D90) is 62.542μm, the particle size (D97) is 85.999μm, the particle size (D3,2) is 4.753μm, and the particle size (D4,3) is 23.981μm.

[0060] Embodiment 2:

[0061] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes 46.2% magnesium, 4.3% iron, 2.6% aluminum, 2.4% calcium, 6% silicon, and 38.5% oxygen, and the following steps:

[0062] (1) 83 parts of magnesia powder (containing silicon), 2 parts of calcium hydroxide, 4.8 parts of ferric hydroxide, 2.9 parts of aluminum hydroxide, and 6.9 parts of calcium silicate, wherein each material is ball-milled for 60 minutes to make the powder particle size reach 100 μm, (2) 20 parts of water are added to the above materials after mixing, and stirred into slurry, (3) the slurry is calcined in a converter at 850°C for 2 hours, and (4) the calcined material is passed through a 200-mesh sieve. The particle size (D50) of the powder prepared in this embodiment is 20.7 μm, and the specific surface area is 1180 m 2 / g.

[0063] Example 3: Composition and preparation method of a neutralizer for industrial highly acidic wastewater. The composition includes 58% magnesium, 0.1% iron, 0.2% aluminum, 0.4% calcium, 0.3% silicon, and 41% oxygen, and includes the following steps:

[0064] (1) 99.3 parts of magnesia powder (containing silicon), 0.4 parts of calcium hydroxide, 0.1 parts of ferric hydroxide, and 0.2 parts of aluminum hydroxide, wherein each material is ball-milled for 45 minutes to make the powder particle size reach 50 μm, (2) 40 parts of water are added to the above materials after mixing, and stirred into slurry, (3) the slurry is calcined in a converter at 900°C for 1.5 hours, and (4) the calcined material is passed through a 325 mesh sieve. The particle size (D50) of the powder prepared in this embodiment is 18 μm, and the specific surface area is 1450 m 2 / g.

[0065] Embodiment 4:

[0066] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes 40.5% magnesium, 8.5% iron, 2% aluminum, 9.5% calcium, 8.5% silicon, and 31% oxygen, and includes the following steps:

[0067] (1) 67.6 parts of magnesia powder (containing silicon), 2.2 parts of calcium hydroxide, 15 parts of ferric hydroxide, 0.2 parts of aluminum hydroxide, and 15 parts of calcium silicate, wherein each material is ball-milled for 45 minutes to make the powder particle size reach 50 μm, (2) 40 parts of water are added to the above materials after mixing, and stirred into slurry, (3) the slurry is calcined in a converter at 900°C for 1.5 hours, and (4) the calcined material is passed through a 325 mesh sieve. The particle size (D50) of the powder prepared in this embodiment is 21 μm, and the specific surface area is 1079 m 2 / g.

[0068] Embodiment 5:

[0069] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes the following: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen. The preparation steps are the same as those in Example 1, except that the amount of water added after the materials are mixed is adjusted to 200 parts of water. The particle size (D50) of the powder prepared in this example is 13.7 μm, and the specific surface area is 1278 m 2 / g.

[0070] Embodiment 6:

[0071] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen. The preparation steps are the same as those in Example 1, except that the calcination temperature is adjusted to 700°C. The particle size (D50) of the powder prepared in this example is 25.7 μm, and the specific surface area is 1138 m 2 / g.

[0072] Embodiment 7:

[0073] A composition and preparation method of an industrial highly acidic wastewater neutralizer. The composition includes the following: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen. The preparation steps are the same as those in Example 1, except that the calcination time is adjusted to 3 hours. The particle size (D50) of the powder prepared in this example is 9.7 μm, and the specific surface area is 1438 m 2 / g.

[0074] Comparative Example 1:

[0075] The inorganic powder comprises the following composition: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen. The preparation steps include:

[0076] Step (1) is the same as in Example 1, step (2) the ball-milled materials are mixed uniformly, step (3) the mixed materials are calcined in a converter at 900°C for 1 hour, and (4) the calcined materials are sieved through a 325-mesh screen. The particle size (D50) of the powder prepared in this comparative example is 25 μm, and the specific surface area is 877 m 2 / g.

[0077] Comparative Example 2:

[0078] The inorganic powder comprises the following composition: 35% magnesium, 5.6% iron, 5.0% aluminum, 5.7% calcium, 8.7% silicon, and 40% oxygen, and comprises the following steps:

[0079] (1) 60.75 parts of magnesia powder, 7.75 parts of calcium hydroxide, 7.75 parts of ferric hydroxide, 7.75 parts of aluminum hydroxide, and 16 parts of calcium silicate, wherein each material is ball-milled for 30 minutes to make the powder particle size reach 50 μm, (2) the above materials are mixed evenly, (3) the mixed materials are calcined in a converter at 900°C for 1 hour, and (4) the calcined materials are passed through a 325 mesh sieve. The particle size (D50) of the powder prepared in this embodiment is 35 μm, and the specific surface area is 742 m 2 / g.

[0080] Comparative Example 3:

[0081] According to the raw materials and method of Example 1 of the comparative document CN105107457A, an industrial high-acid wastewater neutralizer was prepared. The particle size (D50) of the powder prepared in this comparative example was 56 μm, and the specific surface area was 685 m 2 / g.

[0082] Comparative Example 4:

[0083] Referring to the preparation method in the reference document CN105107457A, the powder comprises the following composition: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen, and comprises the following steps:

[0084] (1) 88.75 parts of magnesite powder (containing silicon), 3.75 parts of calcium hydroxide, 3.75 parts of ferric hydroxide, and 3.75 parts of aluminum hydroxide, wherein each material is mixed and ball-milled for 20 minutes, (2) the above materials are calcined in a converter at 900°C for 20 minutes, (3) the calcined materials are washed three times with water and dried naturally, and ball-milled for 20 minutes. The powder prepared in this comparative example has a particle size (D50) of 24.7 μm and a specific surface area of ​​1065 m 2 / g.

[0085] Comparative Example 5:

[0086] The industrial high-acid wastewater neutralizer was prepared according to the raw materials and method of Example 1 of the comparative document CN107456944A. The particle size (D50) of the powder prepared in this comparative example is 125 μm, and the specific surface area is 398 m 2 / g.

[0087] Comparative Example 6:

[0088] Referring to the preparation method in the reference document CN107456944A, the powder comprises the following composition: 52.5% magnesium, 2.1% iron, 1.0% aluminum, 2.7% calcium, 1.7% silicon, and 40% oxygen, and comprises the following steps:

[0089] (1) 88.75 parts of magnesia powder (containing silicon), 3.75 parts of calcium hydroxide, 3.75 parts of iron hydroxide, and 3.75 parts of aluminum hydroxide are mixed evenly and reacted in a closed manner at 450°C for 6 hours. (2) The products of the previous reaction are mixed evenly, filled with air at 200°C, and the air filling is continued for 30 minutes. The products are calcined under the same conditions for 20 minutes. (3) The products of the previous reaction are calcined at 750°C for 30 minutes. (4) The calcined products are filled with water vapor and hydrated at high temperature and high pressure (3 atmospheres, 120°C). The hydrated products are microwave dried. (5) The products after microwave drying are ultrasonically crushed and passed through a 200 mesh. The powder prepared in this comparative example has a particle size (D50) of 84μm and a specific surface area of ​​592m 2 / g.

[0090] Effect Example 1: Performance Test Results

[0091] Test method: Place the sample in a dry beaker, place it on a magnetic stirrer at a constant temperature of 40°C, and immediately add a standard citric acid solution (add phenolphthalein reagent), record the time when the test solution just turns red, and use time (s) to represent the activity value (CAA) of the product. The performance test of the embodiment, comparative example and light-burned magnesium oxide product is shown in Table 2.

[0092] Table 2 Product performance test table

[0093]

[0094] As can be seen from the above table, the activities of the calcined products of Examples 1-7 of the present invention are higher than those of the comparative example and light-burned magnesium oxide, and the stability is good. The activities of Examples 1 to 3, Examples 4 (low magnesium content) and 6 (low calcination temperature) are lower than those of Examples 1 to 3, and the process costs of Example 5 (large amount of water added) and Example 7 (long calcination time) are relatively high.

[0095] Effect example 2: Wastewater treatment test

[0096] Test method 1: Take 200ml of Jiangsu Leoch battery lead-acid wastewater, raw water pH = 1.42, lead content 5.12ppm. Use industrial high-acid wastewater neutralizer to adjust pH = 8~8.5, add 1 / 10000 polyferric chloride, stir for 2~3min, then add appropriate amount of anionic polyacrylamide (0.1% mass concentration), stir slowly for 1~2min, let stand and settle, and measure the reaction time, dosage, sludge output and lead ion content. And after the materials of the embodiment and comparative example are sealed and placed for 180 days, the sludge output and lead ion content are determined in the same test steps. The performance test of the embodiment, comparative example and light-burned magnesium oxide product in treating lead-containing wastewater is shown in Table 3.

[0097] Table 3 Product performance test table for treating lead-containing wastewater

[0098]

[0099] As can be seen from the above table, the calcined products of Examples 1 to 3 of the present invention have greater advantages in reaction time (i.e., the time required for the neutralizer of the industrial high-acid wastewater to adjust pH to 8 to 8.5), dosage of reagents, and mud production in battery lead-acid wastewater than the products of Comparative Examples 4 and 6 and light-burned magnesium oxide. Products that do not adopt the preparation method of the present invention have single or multi-phase disadvantages in reaction time, dosage, mud production, and use data after storage.

[0100] Test method 2: Take 200ml of electroplating wastewater from Zhenjiang Heyun Industrial Wastewater Company, the raw water pH = 2.85, the nickel content is 52ppm, and the chromium content is 2.1ppm. Use industrial high-acid wastewater neutralizer to adjust the pH to 8~8.5, add 1 / 10000 polyferric chloride, stir for 2~3min, then add an appropriate amount of anionic polyacrylamide (0.1% mass concentration), stir slowly for 1~2min, let it stand and settle, and measure the reaction time, dosage, sludge output and nickel and chromium ion content. And after the materials of the embodiment and comparative example are sealed and placed for 180 days, the sludge output and nickel and chromium ion content are determined in the same test steps. The performance test of the embodiment, comparative example and light-burned magnesium oxide product in treating nickel-containing and chromium-containing wastewater is shown in Table 4.

[0101] Table 4 Product performance test table for treating nickel and chromium-containing wastewater

[0102]

[0103] As can be seen from the above table, the calcined products of Examples 1 to 3 of the present invention have greater advantages in terms of reaction time (i.e., the time required for the neutralizer of the industrial highly acidic wastewater to adjust the pH to 8 to 8.5), dosage of reagents, and mud production in electroplating wastewater than the products of Comparative Examples 4 and 6 and light-burned magnesium oxide. Products that do not adopt the preparation method of the present invention have single or multi-phase disadvantages in terms of reaction time, dosage, mud production, and usage data after storage.

[0104] The above description is only an illustrative specific implementation mode of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by a technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention. In addition, the different embodiments and different embodiment features described in this specification can be combined and combined by a technician in the field without contradicting each other. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. A person of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An industrial highly acidic wastewater neutralizer, characterized in that: The composition by mass ratio is: 45-60% magnesium, 0.05-10% iron, 0.05-10% aluminum, 0.05-10% calcium, 0.05-10% silicon, and the balance is oxygen, and the mass ratio of oxygen is more than 30%; the neutralizing agent is a powder, which is prepared by a wet calcination method, and the iron, aluminum, calcium and silicon elements exist in the form of active silicates and active aluminates; The preparation method of the industrial highly acidic wastewater neutralizer comprises the following steps: (1) Crushing and pulverizing the raw materials containing magnesium; (2) crushing and pulverizing raw materials containing iron, aluminum, calcium and silicon elements separately or in combination; (3) The powder materials obtained in steps (1) and (2) are fully mixed according to the element ratio, and water is added during the mixing process to form a uniform slurry between the materials; (4) directly calcining the aqueous slurry; (5) Slowly cool the calcined material to room temperature and then sieve it to remove large particles to obtain the target product; The specific surface area of ​​the industrial highly acidic wastewater neutralizer is 800-1500 m 2 / g; The calcination temperature of the industrial highly acidic wastewater neutralizer is 600-1200°C.

2. The industrial highly acidic wastewater neutralizer according to claim 1, characterized in that: The particle size of the neutralizer is 1-100 μm.

3. The industrial highly acidic wastewater neutralizer according to claim 1, characterized in that: The 180-day activity reduction value of the neutralizer is less than 10, and the 180-day activity reduction value is the difference between the citric acid activity value CAA , =CAA 180 -CAA0, CAA0 represents the initial activity value after preparation, CAA 180 It indicates the activity value 180 days after preparation.

4. The method for preparing the neutralizer for industrial highly acidic wastewater according to any one of claims 1 to 3, characterized in that The method comprises the following steps: (1) crushing and pulverizing raw materials containing magnesium; (2) crushing and pulverizing raw materials containing iron, aluminum, calcium and silicon alone or in combination; (3) fully mixing the powder materials obtained in steps (1) and (2) according to the element ratio, and adding water during the mixing process to form a uniform slurry between the materials; (4) directly calcining the water-containing slurry; (5) slowly cooling the calcined materials to room temperature and then sieving them to remove large particles to obtain the target product.

5. The preparation method according to claim 4, characterized in that: The raw material containing magnesium element is selected from one or more of magnesite, dolomite, magnesium hydroxide and magnesium carbonate.

6. The preparation method according to claim 4, characterized in that: The raw materials containing iron, aluminum, calcium and silicon are selected from one or more of nitrates, carbonates, basic carbonates, silicates, chlorides and hydroxides.

7. Use of the industrial highly acidic wastewater neutralizer according to any one of claims 1 to 3 in treating industrial highly acidic wastewater.

8. The use according to claim 7, characterized in that The anions of the acidic wastewater are sulfate, chloride, fluoride, phosphate, nitrate and acetate.

9. The use according to claim 7, characterized in that The cations in the acidic wastewater are heavy metal ions.

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