Method for preparing hydroxyl aluminum chloride by screening aluminum particles from aluminum ash

Abstract

The invention discloses a method for preparing hydroxyl aluminum chloride by screening aluminum particles from aluminum ash, which comprises the following steps: S1, a pretreatment stage: washing and screening an aluminum particle raw material, S2, an acidolysis reaction stage: putting the pretreated coarse aluminum particles into a filter cloth bag and putting into a reaction kettle, adding hydrochloric acid into the reaction kettle and starting stirring and heating, the reaction temperature is controlled to be 50-70 DEG C; s3, in a hydrolytic polymerization stage, after dropwise adding hydrochloric acid, controlling the reaction temperature to be 60-80 DEG C, after a period of time, putting fine aluminum particles into a filter cloth bag, putting the filter cloth bag into the reaction kettle, and continuously keeping the reaction until the reaction is finished; s4, a homogenizing stage: stirring for a certain time at a proper temperature; and S5, carrying out filter pressing treatment on the liquid to obtain a pure hydroxyl aluminum chloride solution. The technology is green, efficient and safe, the aluminum oxide content of the obtained high-aluminum high-basicity hydroxyl aluminum chloride is larger than or equal to 23%, the basicity is larger than or equal to 85%, the appearance is clear and transparent, the impurity content is controllable, and the standard of foreign water treatment agents is met.

Description

Technical Field

[0001] The invention relates to the field of water purifiers, and in particular to a method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash. Background Art

[0002] Hydroxyaluminum chlorohydrate (ACH), also known as hydroxyaluminum chloride, is a highly concentrated solution of polyaluminum chloride, which is easily soluble in water and has the characteristics of high aluminum content, high basicity and high purity. At present, there are two common preparation processes of hydroxyaluminum chloride. One is to use pure aluminum ingots or aluminum sheets to react with hydrochloric acid, and change the basicity by adding a regulator to achieve the desired effect. Pure aluminum ingots are relatively dense, and the surface of market aluminum ingots is coated with an antioxidant film, which affects the reaction activity; pure aluminum sheets are not easy to process, the reaction activity is large and violent, and there are safety hazards; in addition, the addition of regulators also brings in some unnecessary impurities and salts, which increases costs, and the different purity of pure aluminum ingots also affects the purity of the product.

[0003] As environmental protection conditions become more and more stringent, the market demand for high-quality products is more urgent. Many water treatment units are more pursuing products with colorless and transparent appearance, low cost, low heavy metal content, and even close to the indicators of foreign aluminum hydroxychloride water treatment agents. Therefore, a high-purity and low-cost aluminum hydroxychloride product was developed.

[0004] The present invention uses aluminum ash to screen aluminum particles to prepare aluminum hydroxychloride, fully utilizing the resource advantage of solid waste byproduct aluminum particles, and at the same time, controls the reaction by deploying aluminum particles of different particle sizes, and uses a two-step purification process to improve the purity of the product. A low-cost, high-purity, high-aluminum-content, high-basicity aluminum hydroxychloride product is obtained, and the performance effect is far superior to the polyaluminum chloride products on the market. Summary of the invention

[0005] The invention aims to provide a method for preparing aluminum hydroxychloride by utilizing aluminum ash byproduct aluminum particles, which has low cost, high efficiency and green process, and the obtained aluminum hydroxychloride product has excellent performance.

[0006] The present invention provides a method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash, comprising the following steps: Step 1: Wash the aluminum granules with a reagent, and then screen and grade the washed aluminum granules to obtain coarse aluminum granules and fine aluminum granules; Step 2: Add water to the reactor, place the crude aluminum particles obtained in step 1 in a filter cloth bag and put it into the reactor, slowly add hydrochloric acid to the reactor and start stirring and heating, control the stirring speed to 300-500r / min, control the reactor temperature to 50℃-70℃, add hydrochloric acid dropwise for 4-6 hours, and stop adding hydrochloric acid until the aluminum oxide content in the solution reaches about 4.0-6.0%; Step 3: After the hydrochloric acid is added, the reaction temperature is controlled at 60-80°C. After the reaction lasts for 4-6 hours, the fine aluminum particles are placed in a filter bag and put into the reactor. The reaction is continued for 4-6 hours until the reaction is completed. Step 4: Keep the liquid in step 3 at 50-60°C and stir for 4-6 hours to complete homogenization; Step 5: The homogenized liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

[0007] In step one, aluminum particles are graded and screened to obtain aluminum particles of different size distributions, and the aluminum particles are graded and added; in step two, large-sized aluminum particles are added, and the reaction rate can be adjusted by controlling the hydrochloric acid addition speed to avoid excessive acidity. At the same time, the specific surface area of ​​large-sized aluminum particles is relatively low, and the contact area between the surface of the aluminum particles and the acid is small, which can avoid violent reactions and reduce the gas generation rate; in step three, small-sized aluminum particles are added. The small size has a high specific surface area and many active contact points. At the same time, small-sized aluminum particles have less impurities, which can improve the reaction efficiency and achieve the purification and impurity removal effect.

[0008] The amount of aluminum particles added is 200-400% of the theoretical amount, preferably 400%. The second step is mainly to hydrolyze aluminum chloride to produce hydrochloric acid to continue to dissolve aluminum to increase the aluminum content in the solution, and secondly to hydrolyze aluminum to increase the aluminum content and basicity. The actual amount of aluminum is much higher than the theoretical amount, which can provide more reactive sites, increase acidolysis and hydrolysis reactions, and reduce process time.

[0009] Furthermore, the agent is a mixture of one or more components of dilute hydrochloric acid, dilute sulfuric acid, and citric acid with water.

[0010] Furthermore, the aluminum particles are irregularly spherical, flat or short rod-shaped, the size of the coarse aluminum particles is 0.5-1.5 cm, and the size of the fine aluminum particles is 0.05-0.50 cm.

[0011] Furthermore, the amount of water added is 200-400% of the total amount of aluminum material, the amount of coarse aluminum particles added is 50-70% of the total amount of aluminum material added, the amount of fine aluminum particles added is 30-50% of the total aluminum material mass, the total aluminum material added is 200-400% of the theoretical aluminum material added, the hydrochloric acid concentration is 20-30%, and the amount of hydrochloric acid added is 100-300% of the total amount of aluminum material.

[0012] Furthermore, the filter cloth bag is made of one of polyester fiber, polypropylene fiber and polytetrafluoroethylene, the filter cloth bag has 1 to 5 layers and a pore size of 0.5 to 20 μm.

[0013] The high-aluminum and high-basicity aluminum hydroxychloride prepared by the method of the present invention has a clear and transparent appearance, a controllable impurity content and reaches the foreign drinking water grade water treatment agent standard, and its aluminum oxide content is ≥23% and the basicity is ≥85%.

[0014] The beneficial effects of the present invention are embodied in: (1) Utilize aluminum particles, a byproduct of solid waste, to achieve efficient recycling of aluminum; at the same time, use the size, surface morphology and other characteristics of the screened aluminum particles to increase the reaction rate, reduce costs and shorten the process time.

[0015] (2) Raw material pretreatment and filter cloth impurity removal processes can achieve product purity control, meet performance requirements, and control the reaction rate at the same time.

[0016] (3) The aluminum particles are graded and added twice to improve the reaction efficiency. At the same time, the secondary addition of aluminum particles can purify and remove impurities.

[0017] (4) This method does not require the addition of a basicity regulator to change the basicity, but rather adjusts the basicity through the rate of aluminum hydrolysis.

[0018] ACH Level Water treatment grade (liquid) Drinking water (liquid) Homemade products (liquid) Implementation Standards USP-34 GB15982 Appearance Slightly hazy liquid Clear liquid <![CDATA[Aluminum Oxide (Al2O3) %]]> 21.9-23.8 ＞10 ＞23 Basicity% 75-90 45-90 ＞85 Iron ppm ≤ 75 ≤ 2000 ＜70 Chromium (Cr) ppm ≤ 5.0 ＜2.0 <![CDATA[Chromium (Cr 6+ ), ppm]]> ≤ 1.0 ＜1.0 Arsenic (As) ppm ≤ 1.0 ≤ 1.0 ＜0.5 Heavy metal (Pb) ppm ≤ 5.0 ≤ 5.0 3.0 Nickel (Ni) ppm ≤ 1.0 ＜1.0 Cadmium (Cd) ppm ≤ 1.0 ≤ 1.0 ≤ 1.0 Mercury (Hg) ppm ≤ 0.1 ≤ 0.1 ≤ 0.1 DETAILED DESCRIPTION

[0019] The content of the present invention is further described below in conjunction with the examples. The examples are not intended to limit the scope of protection of the present invention. Without departing from the essence of the technical solution of the present invention, modifications or substitutions made to the method, steps or conditions of the present invention all belong to the scope of the present invention.

[0020] Unless otherwise specified, the equipment, devices and process methods used in the examples are conventional equipment, devices and process methods well known to those of ordinary skill in the art.

[0021] Example 1

[0022] Step 1: In the pretreatment stage, the aluminum particles are washed with dilute hydrochloric acid with a concentration of 0.1 mol / L. After washing, the washed aluminum particles are sieved and graded to obtain coarse aluminum particles and fine aluminum particles. The particle size of the coarse aluminum particles is 1.5 cm, and the particle size of the fine aluminum particles is about 0.5 cm.

[0023] Step 2: During the acid hydrolysis reaction stage, the pretreated crude aluminum particles are placed in a filter cloth bag and put into a reactor. The pore size of the filter cloth bag is 20 μm, the number of layers is 2, and the amount of crude aluminum particles added is 70% of the total aluminum material added. Before adding acid, 400% of the theoretical aluminum material mass of water is pre-selected in the reactor. Hydrochloric acid is slowly added to the reactor and stirring and heating are started. The temperature is maintained at 50°C, the hydrochloric acid concentration is 20%, and the amount added is 400% of the total aluminum material added. The hydrochloric acid addition time is about 12 hours. After the hydrochloric acid addition is completed, the alumina content of the solution is about 4.0-4.5%.

[0024] Step 3: During the hydrolysis polymerization stage, after the addition of hydrochloric acid is completed, the reaction temperature is controlled at 60°C. After reacting for 6 hours, fine aluminum particles are placed in a filter cloth bag and put into the reactor. The size of the fine aluminum particles is 0.5 cm, and the amount added is 35% of the total aluminum material added. The total aluminum material added is 200% of the theoretical aluminum material added. The reaction is continued for 12 hours until the reaction is completed.

[0025] Step 4: During the homogenization stage, stir at 50°C for 6 hours.

[0026] Step 5: The liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

[0027] ACH Level Water treatment grade (liquid) Drinking water (liquid) Homemade products (liquid) Implementation Standards USP-34 GB15982 Appearance Slightly hazy liquid Clear liquid <![CDATA[Aluminum Oxide (Al2O3) %]]> 21.9-23.8 ＞10 22.29 Basicity% 75-90 45-90 78 Iron ppm ≤ 75 ≤ 2000 75 Chromium (Cr) ppm ≤ 5.0 2.0 <![CDATA[Chromium (Cr 6+ ), ppm]]> ≤ 1.0 1.0 Arsenic (As) ppm ≤ 1.0 ≤ 1.0 1.0 Heavy metal (Pb) ppm ≤ 5.0 ≤ 5.0 5.0 Nickel (Ni) ppm ≤ 1.0 1.0 Cadmium (Cd) ppm ≤ 1.0 ≤ 1.0 1.0 Mercury (Hg) ppm ≤ 0.1 ≤ 0.1 0.1 Embodiment 2: Step 1: In the pretreatment stage, the aluminum particles are washed with dilute hydrochloric acid with a concentration of 0.3 mol / L. After washing, the washed aluminum particles are sieved and graded to obtain coarse aluminum particles and fine aluminum particles. The particle size of the coarse aluminum particles is 1.2 cm, and the particle size of the fine aluminum particles is about 0.3 cm.

[0028] Step 2: During the acid hydrolysis reaction stage, the pretreated crude aluminum particles are placed in a filter cloth bag and put into a reactor. The pore size of the filter cloth bag is 15 μm, the number of layers is 3, and the amount of crude aluminum particles added is 65% of the total aluminum material added. Before adding acid, 300% of the theoretical aluminum material mass of water is pre-selected in the reactor. Hydrochloric acid is slowly added to the reactor and stirring and heating are started. The temperature is maintained at 55°C, the hydrochloric acid concentration is 25%, and the amount added is 250% of the total aluminum material added. The hydrochloric acid addition time is about 10 hours. After the hydrochloric acid addition is completed, the alumina content of the solution is about 4.5-5.0%.

[0029] Step 3: During the hydrolysis polymerization stage, after the addition of hydrochloric acid is completed, the reaction temperature is controlled at 65°C. After reacting for 5 hours, fine aluminum particles are placed in a filter cloth bag and put into the reactor. The size of the fine aluminum particles is 0.3 cm, and the amount added is 40% of the total aluminum material added. The total aluminum material added is 300% of the theoretical aluminum material added. The reaction is continued for 10 hours until the reaction is completed.

[0030] Step 4: During the homogenization stage, maintain the temperature at 55°C and stir for 5 hours.

[0031] Step 5: The liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

[0032] ACH Level Water treatment grade (liquid) Drinking water (liquid) Homemade products (liquid) Implementation Standards USP-34 GB15982 Appearance Slightly hazy liquid Clear liquid <![CDATA[Aluminum Oxide (Al2O3) %]]> 21.9-23.8 ＞10 23.1 Basicity% 75-90 45-90 83 Iron ppm ≤ 75 ≤ 2000 60 Chromium (Cr) ppm ≤ 5.0 1.8 <![CDATA[Chromium (Cr 6+ ) ppm]]> ≤ 1.0 0.8 Arsenic (As) ppm ≤ 1.0 ≤ 1.0 0.6 Heavy metal (Pb) ppm ≤ 5.0 ≤ 5.0 4.0 Nickel (Ni) ppm ≤ 1.0 0.6 Cadmium (Cd) ppm ≤ 1.0 ≤ 1.0 0.7 Mercury (Hg) ppm ≤ 0.1 ≤ 0.1 0.08 Embodiment 3: Step 1: In the pretreatment stage, the aluminum particles are washed with dilute hydrochloric acid with a concentration of 0.5 mol / L. After washing, the washed aluminum particles are sieved and graded to obtain coarse aluminum particles and fine aluminum particles. The particle size of the coarse aluminum particles is 1.0 cm, and the particle size of the fine aluminum particles is about 0.10 cm.

[0033] Step 2: During the acid hydrolysis reaction stage, the pretreated crude aluminum particles are placed in a filter cloth bag and put into a reactor. The pore size of the filter cloth bag is 10 μm, the number of layers is 4, and the amount of crude aluminum particles added is 60% of the total aluminum material added. Before adding acid, 400% of the theoretical aluminum material mass of water is pre-selected in the reactor. Hydrochloric acid is slowly added to the reactor and stirring and heating are started. The temperature is maintained at 58°C, the hydrochloric acid concentration is 28%, and the amount added is 200% of the total aluminum material added. The hydrochloric acid addition time is about 8 hours. After the hydrochloric acid addition is completed, the alumina content of the solution is about 4.5-5.0%.

[0034] Step 3: During the hydrolysis polymerization stage, after the addition of hydrochloric acid is completed, the reaction temperature is controlled at 70°C. After reacting for 4.5 hours, fine aluminum particles are placed in a filter cloth bag and put into the reactor. The size of the fine aluminum particles is 0.10 cm, and the amount added is 45% of the total aluminum material added. The total aluminum material added is 350% of the theoretical aluminum material added. The reaction is continued for 9 hours until the reaction is completed.

[0035] Step 4: During the homogenization phase, maintain the temperature at 58°C and stir for 4.5 hours.

[0036] Step 5: The liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

[0037] ACH Level Water treatment grade (liquid) Drinking water (liquid) Homemade products (liquid) Implementation Standards USP-34 GB15982 Appearance Slightly hazy liquid Clear liquid <![CDATA[Aluminum oxide (Al2O3) %]]> 21.9-23.8 ＞10 23.5 Basicity% 75-90 45-90 85 Iron ppm ≤ 75 ≤ 2000 55 Chromium (Cr) ppm ≤ 5.0 1.5 <![CDATA[Chromium (Cr 6+ ) ppm]]> ≤ 1.0 0.6 Arsenic (As) ppm ≤ 1.0 ≤ 1.0 0.5 Heavy metal (Pb) ppm ≤ 5.0 ≤ 5.0 3.0 Nickel (Ni) ppm ≤ 1.0 0.5 Cadmium (Cd) ppm ≤ 1.0 ≤ 1.0 0.4 Mercury (Hg) ppm ≤ 0.1 ≤ 0.1 0.05 Example 4 Step 1: In the pretreatment stage, the aluminum particles are washed with dilute hydrochloric acid with a concentration of 0.8 mol / L. After washing, the washed aluminum particles are sieved and graded to obtain coarse aluminum particles and fine aluminum particles. The particle size of the coarse aluminum particles is 0.8 cm, and the particle size of the fine aluminum particles is about 0.08 cm.

[0038] Step 2: During the acid hydrolysis reaction stage, the pretreated crude aluminum particles are placed in a filter cloth bag and put into a reactor. The pore size of the filter cloth bag is 5μm, the number of layers is 5, and the amount of crude aluminum particles added is 55% of the total aluminum material added. Before adding acid, 400% of the theoretical aluminum material mass of water is pre-selected in the reactor. Hydrochloric acid is slowly added to the reactor and stirring and heating are started. The temperature is maintained at 60°C, the hydrochloric acid concentration is 30%, and the amount added is 150% of the total aluminum material added. The hydrochloric acid addition time is about 7 hours. After the hydrochloric acid addition is completed, the alumina content of the solution is about 4.5-5.0%.

[0039] Step 3: During the hydrolysis polymerization stage, after the addition of hydrochloric acid is completed, the reaction temperature is controlled at 80°C. After reacting for 4.0 hours, fine aluminum particles are placed in a filter cloth bag and put into the reactor. The size of the fine aluminum particles is 0.08 cm, and the amount added is 50% of the total aluminum material added. The total aluminum material added is 400% of the theoretical aluminum material added. The reaction is continued for 8 hours until the reaction is completed.

[0040] Step 4: During the homogenization stage, the temperature was maintained at 60°C and stirred for 4.0 hours.

[0041] Step 5: The liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

[0042] ACH Level Water treatment grade (liquid) Drinking water (liquid) Homemade products (liquid) Implementation Standards USP-34 GB15982 Appearance Slightly hazy liquid Clear liquid <![CDATA[Aluminum oxide (Al2O3) %]]> 21.9-23.8 ＞10 23.8 Basicity% 75-90 45-90 87 Iron ppm ≤ 75 ≤ 2000 50 Chromium (Cr) ppm ≤ 5.0 1.0 <![CDATA[Chromium (Cr 6+ ) ppm]]> ≤ 1.0 0.5 Arsenic (As) ppm ≤ 1.0 ≤ 1.0 0.3 Heavy metal (Pb) ppm ≤ 5.0 ≤ 5.0 2.5 Nickel (Ni) ppm ≤ 1.0 0.4 Cadmium (Cd) ppm ≤ 1.0 ≤ 1.0 0.3 Mercury (Hg) ppm ≤ 0.1 ≤ 0.1 0.03

Claims

1. A method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash, characterized in that: The method for preparing aluminum hydroxychloride specifically comprises the following steps: Step 1: Wash the aluminum granules with a reagent, and then screen and grade the washed aluminum granules to obtain coarse aluminum granules and fine aluminum granules; Step 2: Add water to the reactor, place the crude aluminum particles obtained in step 1 in a filter cloth bag and put it into the reactor, slowly add hydrochloric acid to the reactor and start stirring and heating, control the stirring speed to 300-500r / min, control the reactor temperature to 50℃-70℃, add hydrochloric acid dropwise for 4-6 hours, and stop adding hydrochloric acid until the aluminum oxide content in the solution reaches about 4.0-6.0%; Step 3: After the hydrochloric acid is added, the reaction temperature is controlled at 60-80°C. After the reaction lasts for 4-6 hours, the fine aluminum particles are placed in a filter bag and put into the reactor. The reaction is continued for 4-6 hours until the reaction is completed. Step 4: Keep the liquid in step 3 at 50-60°C and stir for 4-6 hours to complete homogenization; Step 5: The homogenized liquid is subjected to filter pressing to obtain a pure aluminum hydroxychloride solution.

2. The method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash according to claim 1, characterized in that The agent is a mixture of one or more components of dilute hydrochloric acid, dilute sulfuric acid, and citric acid with water.

3. The method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash according to claim 1, characterized in that The aluminum particles are irregularly spherical, flat or short rod-shaped, the size of the coarse aluminum particles is 0.5-1.5 cm, and the size of the fine aluminum particles is 0.05-0.50 cm.

4. The method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash according to claim 1, characterized in that In step 2, the amount of water added is 200-400% of the total amount of aluminum material, the amount of coarse aluminum particles added is 50-70% of the total amount of aluminum material added, the amount of fine aluminum particles added is 30-50% of the total aluminum material mass, the total amount of aluminum material added is 200-400% of the theoretical amount of aluminum material added, the concentration of hydrochloric acid is 20-30%, and the amount of hydrochloric acid added is 100-300% of the total amount of aluminum material.

5. The method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash according to claim 1, characterized in that The filter cloth bag is made of one of polyester fiber, polypropylene fiber and polytetrafluoroethylene, the number of layers of the filter cloth bag is 1-5, and the pore size is 0.5-20μm.

6. The method for preparing aluminum hydroxychloride by screening aluminum particles from aluminum ash according to claim 1, characterized in that , the aluminum hydroxychloride has an aluminum oxide content ≥ 23% and a basicity ≥ 85%.