阅读说明：本技术 一种用热镀锌灰生产陶瓷釉料用氧化锌的方法 (Method for producing zinc oxide for ceramic glaze by using hot-dip galvanizing ash ) 是由 李发武 于 2021-01-12 设计创作，主要内容包括：本发明公开一种用热镀锌灰生产陶瓷釉料用氧化锌的方法,其步骤分别为湿法球磨、过滤除铁、湿法脱氯、烘干煅烧,其将热镀锌灰中的锌以能够直接应用于陶瓷釉料的氧化锌的形式进行回收。本发明将脱氯后的锌灰直接烘干煅烧制得氧化锌产品,不经过高温还原挥发再氧化,提高了锌的回收率,回收率可达到99％,同时节约大量的优质无烟煤(或焦粉)等能源材料,降低了生产成本,具有良好的经济效益；其生产工艺过程清洁环保、全程无固废产生,无烟尘排放,废水零排放,具有良好的环保效益,所制备的氧化锌比重大、流动性好、挥发份低,能够直接应用于陶瓷釉料行业。(The invention discloses a method for producing zinc oxide for ceramic glaze by hot dip galvanizing ash, which comprises the steps of wet ball milling, filtering for removing iron, wet dechlorination, drying and calcining, wherein zinc in the hot dip galvanizing ash is recovered in a form of zinc oxide which can be directly applied to ceramic glaze. According to the invention, the zinc ash after dechlorination is directly dried and calcined to prepare the zinc oxide product, and the zinc oxide product is not subjected to high-temperature reduction, volatilization and reoxidation, so that the recovery rate of zinc is improved and can reach 99%, and meanwhile, a large amount of energy materials such as high-quality anthracite (or coke powder) and the like are saved, the production cost is reduced, and the zinc oxide product has good economic benefits; the production process is clean and environment-friendly, no solid waste is generated in the whole process, no dust is discharged, zero discharge of waste water is realized, good environmental benefits are achieved, and the prepared zinc oxide is high in specific gravity, good in fluidity and low in volatile matter, and can be directly applied to the ceramic glaze industry.)

1. A method for producing zinc oxide for ceramic glaze by using hot dip galvanizing ash is characterized by comprising the following steps:

s1: wet ball milling

Finely grinding the zinc ash by using a ball mill, and sieving 80 percent of materials at the outlet of the ball mill by using a 150-200-mesh sieve;

s2: filtering for removing iron

Filtering and removing ferromagnetic substances in the slurry subjected to ball milling of S1 by using an iron remover;

s3: wet dechlorination

Adding the slurry subjected to iron removal in the step S2 into a reaction kettle, adding sodium carbonate or sodium hydroxide, heating, stirring and reacting until the pH value of the material is 8-9, and finishing the reaction; discharging the ore pulp after the reaction is finished, washing the ore pulp with water after dehydration, and dehydrating again, wherein the Cl mass content in the dehydrated dechlorinated zinc ash is lower than 0.5 percent, and the dechlorinated zinc ash is a mixture of zinc oxide, zinc carbonate or zinc hydroxide and metal zinc;

s4: drying and calcining

And calcining the dechlorinated zinc ash to obtain a zinc oxide product.

2. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the zinc oxide product prepared in step S4 has a zinc oxide content of 80-97% by mass.

3. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein water is added by wet ball milling in step S1, wherein the water is added according to a solid-to-liquid ratio of zinc ash of 1:3-5 (mass fraction).

4. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the ferromagnetic substance in step S2 is mainly metallic iron powder.

5. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the reaction vessel used in step S3 is a reaction vessel with a stirrer, and the stirring speed of the slurry is controlled to be 100-150r/min and the temperature is controlled to be 80-100 ℃ when the slurry is reacted with sodium carbonate or sodium hydroxide.

6. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the reaction time of step S3 is 0.5-1.5 hours.

7. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the sodium carbonate or sodium hydroxide in step S3 is added in solid form or in solution form.

8. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the amount of sodium carbonate added is 1.6 to 1.8 times (by mass) the chlorine content in the ore slurry when the sodium carbonate is added to react with the ore slurry in step S3; step S3, when sodium hydroxide is added to react with the ore pulp, the adding amount of the sodium hydroxide is 1.15-1.3 times of the chlorine element content (mass) in the ore pulp.

9. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein step S4 is implemented by calcining dechlorinated zinc ash in a rotary kiln, and the combustion medium can be one of No. 0 diesel, coal gas or natural gas; and introducing oxygen or oxygen-enriched air into the rotary kiln in the calcining process so as to fully convert the metal zinc into zinc oxide (ZnO).

10. The method for producing zinc oxide for ceramic glaze according to claim 1, wherein the ammonia gas (NH) generated during the reaction of step S3 is generated₃) Absorbing by using an ammonia absorption tower; and recovering NaCl from the generated salt-containing (NaC1) waste liquid by adopting evaporative crystallization equipment, and returning the water after recovering the NaCl to the process for recycling.

Technical Field

The invention relates to the technical field of zinc oxide production processes, in particular to a clean, environment-friendly and high-recovery-rate process technology for producing zinc oxide for ceramic glaze by using hot-dip galvanizing ash.

Background

Zinc oxide is an important flux raw material in the ceramic chemical industry, and is widely used in tile glaze, semi-transparent glaze of crude pottery and transparent after-glaze fired glaze of craft tableware in the ceramic industry. Especially, the usage amount of the building ceramic wall and floor tile glaze and low-temperature glaze is more.

The zinc oxide has stronger fluxing action in the glaze, can reduce the expansion coefficient of the glaze, improve the thermal stability of products, simultaneously can increase the luster and whiteness of the glaze surface, improve the elasticity of the glaze, and can increase the luster of the glaze color while expanding the melting range.

The zinc oxide is used in the raw glaze, and is calcined at high temperature of about 1200 ℃ to reduce the shrinkage of the glaze in the firing process and reduce the defects of bald glaze, bubbles, pinholes and the like caused by the shrinkage. The zinc oxide is used in the ceramic frit without calcination and can be used directly.

At present, zinc oxide for low-end ceramic glaze mainly uses zinc oxide with the content of 80-90 percent produced by a rotary kiln and a fuming furnace; the zinc oxide for the middle-end ceramic glaze is mainly 90-95% of zinc oxide produced by an open hearth furnace. The rotary kiln and the fuming furnace mostly adopt zinc-containing waste materials (such as blast furnace dust, lead-smelting blast furnace slag and the like) generated in the metallurgical industry as raw materials, so that the quality of zinc oxide products is extremely unstable. The zinc oxide produced by open hearth furnace is stable in quality, because the open hearth furnace uses zinc calcine (primary calcine or regenerated calcine) as raw material (the dechlorinated zinc ash prepared by said process also can be used as raw material for producing zinc oxide by open hearth furnace), and uses high-quality anthracite or coke powder as reducing agent and fuel, so that its energy consumption and cost are high, at the same time, the open hearth furnace production process can produce lots of solid wastes (furnace slag) and smoke dust, and its environmental pollution is large.

The hot galvanizing ash is a solid zinc-containing material generated in the production process of hot galvanizing of steel. The content of zinc element in the hot galvanizing ash is as high as 60-80%, and the zinc element mainly exists in the forms of zinc oxide (ZnO), metal zinc and zinc chloride (ZnCl 2). The hot-dip galvanizing production uses 0# zinc ingot as raw material, therefore, the content of harmful heavy metal elements such as lead, cadmium and the like in zinc ash is extremely low, and the hot-dip galvanizing ash is a high-quality zinc-containing material which can be recycled for the second time. Ammonium chloride (NH4Cl) and zinc chloride (ZnCl2) are used as plating aids in the hot galvanizing process, so that the content of chlorine in zinc ash is high, and the chlorine mainly exists in the forms of (ZnCl2) and ammonium chloride (NH4 Cl). Zinc chloride (ZnCl2) can not be reduced by a carbonaceous reducing agent in the process of pyrometallurgical zinc smelting, but volatilizes and enters a dust collecting system. Meanwhile, Zncl2 has strong corrosivity and serious corrosion to smelting equipment. In the process of zinc hydrometallurgy, chloride ions in the electrolyte can corrode an anode plate (commonly called as a 'sintered plate'). Therefore, the zinc ash is recycled, and chlorine in the zinc ash is removed firstly.

Because of the difference in the process, zinc ash (commonly called as 'iron tower ash' in the industry) generated in the hot dip galvanizing process of angle steel, channel steel, I-shaped steel and the like has 3-8% of chlorine content, and the chlorine element content of the zinc ash (commonly called as 'pipe ash' in the industry) generated in the hot dip galvanizing process of steel pipes reaches 10-20%.

Disclosure of Invention

The invention provides a clean, environment-friendly and high-recovery-rate zinc oxide production process technology for ceramic glaze, aiming at the characteristics of hot-galvanized pipe ash and the use requirement of zinc oxide for the ceramic glaze. The technical scheme of the invention comprises the following steps:

a method for producing zinc oxide for ceramic glaze by hot galvanizing ash comprises the following steps:

s1: wet ball milling

Finely grinding the zinc ash by using a ball mill, and sieving 80 percent of materials at the outlet of the ball mill by using a 150-200-mesh sieve;

s2: filtering for removing iron

Filtering and removing ferromagnetic substances in the fine material sieved by the S1 by using an iron remover;

s3: wet dechlorination

Adding the slurry subjected to iron removal in the step S2 into a reaction kettle, adding sodium carbonate or sodium hydroxide, heating, and stirring for reaction; after the reaction, the reaction is finished until the pH value of the material is 8-9; discharging the ore pulp after the reaction is finished, washing the ore pulp with water after dehydration, and dehydrating again, wherein the Cl mass content in the dehydrated dechlorinated zinc ash is lower than 0.5 percent, and the dechlorinated zinc ash is a mixture of zinc oxide, zinc carbonate or zinc hydroxide and metal zinc;

s4: drying and calcining

And calcining the dechlorinated zinc ash to obtain a zinc oxide product, wherein the zinc oxide content of the prepared zinc oxide product is 80-97%.

Further, water is added in the step S1 through wet ball milling, and the water is added according to the solid-to-liquid ratio (mass fraction) of the zinc ash of 1: 3-5.

Further, the ferromagnetic substance in step S2 is mainly metallic iron powder.

Further, the reaction kettle used in the step S3 is a reaction kettle with a stirrer, when the ore pulp reacts with sodium carbonate or sodium hydroxide, the stirring speed is controlled at 100 and 150r/min, and the temperature is controlled at 80-100 ℃.

Further, the reaction time of step S3 is 0.5 to 1.5 hours.

Further, sodium carbonate or sodium hydroxide in step S3 is added in a solid form, or in a solution form.

Further, when sodium carbonate is added in the step S3 to react with the slurry, the adding amount of the sodium carbonate is 1.6-1.8 times of the chlorine content (mass) in the ore pulp;

the chemical reactions involved in this process are:

ZnCl₂+Na₂CO₃＝ZnCO₃↓+2NaCl

2NH₄Cl+Na₂CO₃＝2NaCl₂+2NH₃↑+CO₂↑+H₂0

further, when the sodium hydroxide is added in the step S3 to react with the slurry, the adding amount of the sodium hydroxide is 1.15 to 1.3 times of the content (mass) of the chlorine element in the ore pulp;

the chemical reactions involved in this process are:

ZnCl₂+2NaOH＝Zn(OH)₂↓+2NaCl

NH₄Cl+Na(OH)＝NaCl+NH₃↑+H₂0

further, step S4, calcining the dechlorinated zinc ash in a rotary kiln, wherein the combustion medium may be one of 0# diesel, coal gas or natural gas; introducing oxygen or oxygen-enriched air into the rotary kiln in the calcining process to fully convert the metal zinc into zinc oxide (ZnO), and controlling the calcining temperature at 900-1200 ℃.

The chemical reaction involved in step S4 is:

2Zn+0₂＝2Zn0

further, ammonia (NH) gas generated during the reaction of step S3₃) Absorbing by using an ammonia absorption tower; and recovering NaCl from the generated salt-containing (NaC1) waste liquid by adopting evaporative crystallization equipment, and returning the water after recovering the NaCl to the process for recycling.

By adopting the technical scheme, the beneficial effects are as follows:

1. according to the invention, the zinc ash after dechlorination is directly dried and calcined to prepare the zinc oxide product, and the zinc oxide product is not subjected to high-temperature reduction, volatilization and reoxidation, so that the recovery rate of zinc is improved and can reach 99%, a large amount of energy materials such as high-quality anthracite (or coke powder) can be saved, the production cost is reduced, and good economic benefits are achieved;

2. the production process is clean and environment-friendly, no solid waste is generated in the whole process, no smoke and dust is discharged, zero waste water discharge is realized, and good environment-friendly benefits are achieved.

3. The zinc oxide prepared by the method has high specific gravity, good fluidity and low volatile matter, and can be directly applied to the ceramic glaze industry.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Those used in the following examples, which are not specifically indicated, were carried out according to the conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

And then preparing zinc oxide for the ceramic glaze by using byproduct zinc ash produced by different hot-dip galvanized pipe manufacturers as a raw material. The zinc ash produced by the galvanizing factory is a mixture of block, granule and powder, and small block, granule and powder metal zinc. The zinc ash used in the examples described below was the fine ash remaining after the separation of small lumps and coarse particles of metallic zinc by dry milling and sieving.

Example 1: selecting a comprehensive sample of zinc ash (plating pipe ash) of 30 hot-dip galvanizing factories in the Qiu county of the Tianjin quiet sea area, wherein the content (quality) of each component detected by the zinc ash is as follows: 62.14% Zn, 0.34% Pb, Al₂O₃% of 6.8%, As% < 0.1%, Cr% of 0.025%, Cd% < 0.005%, Cl% of 11.44%, F% of 0.021%, S% of 0.015%, P% of 0.030%, SiO₂Less than 0.5 percent, 0.11 percent of CaO, 0.029 percent of MgO, 0.011 percent of Cu, 0.025 percent of Ni, 0.40 percent of Fe, 0.016 percent of K, 0.041 percent of Mn and less than 0.0005 percent of Hg.

The preparation steps of the zinc oxide are as follows:

s1: wet ball milling

Taking 500g of sample, grinding by a small ball mill until 80% of the sample passes through a 150-mesh sieve, and controlling the water amount for ball milling to 2000 ml;

s2 filtering to remove iron

Filtering and removing iron from the ball-milled slurry of S1 by using a slurry iron remover;

s3: wet dechlorination

And (3) adding the slurry subjected to iron removal in the step S2 into a reaction kettle, stirring, adding 70g of sodium hydroxide (NaOH) at the rotation speed of the stirrer of 150r/min, heating to the temperature of 95 ℃, and reacting for 1 hour. Filtering, washing the filter cake with distilled water until the mass content of Cl ions is less than 0.5%, and obtaining dechlorinated zinc ash.

S4: drying and calcining

Dividing the dechlorinated zinc ash filter cake into two parts, wherein one part is dried and then sent into a muffle furnace, heating to 900 ℃ and calcining for 1 hour to obtain a white zinc oxide product, sampling and detecting to obtain 90.28 mass percent of ZnO, the other part is dried and then sent into the muffle furnace, heating to 1100 ℃ and calcining for half an hour to obtain a light yellow calcined zinc oxide product, and sampling and detecting to obtain 92.15 mass percent of ZnO, so that in the step of drying and calcining, the higher the calcining temperature is, the higher the ZnO content in the prepared material is.

Example 2: selecting zinc-coated pipe ash of a certain galvanizing factory in Yuxi Yunnan, wherein the zinc ash detection comprises the following components in percentage by mass: 66.51% Zn, 12.54% Cl, ZnCO₃% of 2.31, Fe% of 0.41, Pb% of 0.32, Cd% of 0.03, S% of 0.21, Al₂O₃% is 2.15. When the plant plates the tubules, a part of powdered metallic zinc powder was produced, the metallic powder having a Zn% of 97.1% and a C1% of 0.35%, and this part of metallic powder was mixed with zinc ash, so that the zinc ash as a raw material in this example had a relatively high content of zinc element.

The preparation steps of the zinc oxide are as follows:

s1: wet ball milling

Taking 500g of sample, grinding by a small ball mill until 80% of the sample passes through a 150-mesh sieve, and controlling the water consumption of ball milling to 2000 ml;

s2 filtering to remove iron

Filtering and removing iron from the ball-milled slurry of S1 by using a slurry iron remover;

s3: wet dechlorination

And (3) adding the slurry subjected to iron removal in the step S2 into a reaction kettle, stirring, adding 75g of sodium hydroxide (NaOH) at the rotation speed of the stirrer of 150r/min, heating to the temperature of 90 ℃, and reacting for 1 hour. Filtering and dehydrating, washing a filter cake with distilled water until the mass content of Cl ions is lower than 0.5%, and obtaining dechlorinated zinc ash.

S4: drying and calcining

And (3) transferring the dechlorinated zinc ash filter cake into a muffle furnace, heating to 1100 ℃, calcining for 0.5h to obtain a yellow calcined zinc oxide product, and sampling to detect that the mass content of ZnO is 96.15%.

Example 3: selecting and fixing tube ash of a certain galvanizing factory in Hebei, wherein the content (quality) of each component detected by the zinc ash is as follows: 55.18% Zn, 14.52% Cl, 0.25% Fe, 0.38% Pb, 0.48% Cd, 0.23% S, Al₂O₃% is 8.78.

The preparation steps of the zinc oxide are as follows:

s1: wet ball milling

Taking 500g of sample, grinding by a small ball mill until 80% of the sample passes through a 150-mesh sieve, and controlling the water consumption of the ball mill to be 2500 ml;

s2 filtering to remove iron

Filtering and removing iron from the ball-milled slurry of S1 by using a slurry iron remover;

s3: wet dechlorination

Adding the slurry subjected to iron removal in the step S2 into a reaction kettle, stirring, adding 90g of Na at the rotating speed of a stirrer of 100r/min₂CO₃The reaction was heated to 95 ℃ and reacted for 1.5 hours. Filtering and dehydrating, washing a filter cake with distilled water until the mass content of Cl ions is lower than 0.5%, and obtaining dechlorinated zinc ash.

S4: drying and calcining

And (3) transferring the dechlorinated zinc ash filter cake into a muffle furnace, heating to 900 ℃, calcining for 1.5 hours to obtain a white zinc oxide product, and sampling to detect that the mass content of ZnO is 88.50%.

The present invention and the embodiments thereof have been described above, but the description is not limited thereto, and the embodiments shown in the above embodiments are only one of the embodiments of the present invention, and the actual configuration is not limited thereto. In summary, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the spirit and scope of the invention as defined by the appended claims.