Method for hydrogen group reduction dezincification of zinc-containing dust

Abstract

The invention belongs to the technical field of ferrous metallurgy, and discloses a hydrogen group reduction dezincification method for zinc-containing dust. According to the method, biomass is used as a reducing agent, the volatile components are multiple, the reduction removal effect of the zinc element in the zinc-containing dust can be effectively enhanced, the source is wide, the environmental pollution is reduced, the functionalization and resource utilization of solid waste are realized, and the process treatment cost is reduced. Calcium oxide can promote zinc-iron separation, so that the dezincification rate is increased, and the consumption of a carbon reducing agent is reduced. The tar residue powder has good viscosity and has a bonding effect during pelletizing, so that the strength of the dry ball is enhanced, and the dispersity of each material can be improved. After calcium chloride is added, zinc can form zinc chloride with a lower boiling point in the volatilization reaction process, and the dezincification rate is increased. The reducing atmosphere is a mixed gas of H2 and CO, the reduction dezincification effect is better than that of a single reducing gas, and the method is suitable for large-scale application in factories.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and more specifically relates to a method for hydrogen-based reduction dezincification of zinc-containing dust. Background Art

[0002] Zinc is an important metal raw material with good calendering, wear resistance and corrosion resistance. It is widely used in metallurgy, machinery and other fields. Its consumption in non-ferrous metals is second only to copper and aluminum. The "China Zinc Industry Chain Annual Report" shows that the price of zinc ingots in 2020-2023 is higher than 20,000 yuan / ton, which is a material with high economic value. Large-scale consumption has led to an increase in zinc supply output, which has reached 656.1t / a in 2021, but China's domestic zinc ore reserves are limited, about 4,400t / a, which cannot meet the growing demand in the long term. In order to cope with the crisis of insufficient zinc ore, the recovery of secondary zinc resources is imminent.

[0003] In recent years, my country's economic development has been very rapid. With the continuous improvement and development of infrastructure and infrastructure, the demand for steel resources in the whole society has also increased year by year. In the entire smelting process, steel enterprises will not only consume a lot of resources and energy, but also be accompanied by the discharge of a large amount of solid waste, such as zinc-containing dust. In 2019, with the increase in crude steel production, the output of dust and mud was about 105 million tons, and the total amount of dust generated during the smelting process accounted for more than 10% of the total steel production. If the zinc in the dust ash can be recovered and the dezincified ash is returned to the smelting production, it can effectively alleviate the accumulation problem of dust ash in the steel plant while improving the comprehensive utilization rate of dust ash and increasing the economic benefits of the enterprise. At present, there are two main methods for treating zinc-containing dust: pyrometallurgical process and hydrometallurgical process. The hydrometallurgical process mainly uses the characteristic that zinc oxide can be dissolved in acid and alkali, and uses acid or alkali leaching solutions to separate and collect zinc, but there are problems such as low leaching rate, easy corrosion of equipment, and cumbersome iron precipitation process in the later leaching solution. Pyrometallurgical dezincification is the most commonly used dust dezincification process in current steel mills, with high process energy consumption and low utilization rate of valuable elements.

[0004] Therefore, how to provide a method for hydrogen-based reduction dezincification of zinc-containing dust is a problem that technicians in this field urgently need to solve. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the present invention provides a method for hydrogen-based reduction dezincification of zinc-containing dust.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for dezincification of zinc-containing dust by hydrogen-based reduction, comprising the following steps:

[0008] (1) drying the biomass, crushing it in a ball mill, and sieving it to obtain biomass powder;

[0009] (2) mixing zinc-containing dust, biomass powder, calcium oxide, bentonite, tar residue powder, and calcium chloride solution uniformly to obtain a mixture;

[0010] (3) pelletizing the mixed material in a disc pelletizing machine to obtain green pellets, and then drying to obtain dry pellets;

[0011] (4) The dry ball is heated to 500° C. under a protective atmosphere of N2, and then H2 and CO are introduced for secondary heating, and high-temperature reduction is carried out in the mixed gas. After the reduction is completed, the temperature is lowered under the protection of argon gas and cooled to room temperature to obtain dezincified reduced pellets.

[0012] Preferably, the biomass in step (1) is selected from one or more of coconut shells, peanut shells, walnut shells, melon seed shells, palm shells, cocoa shells, sugarcane bagasse, and traditional Chinese medicine residues.

[0013] Preferably, the drying temperature in step (1) is 70-80° C., the drying time is 0.5-2 h, and the powder is sieved through a 100-150 mesh sieve after being crushed.

[0014] Preferably, the zinc-containing dust in step (2) includes one or more of electric furnace dust, converter dust, iron oxide scale, blast furnace bag ash, and blast furnace gravity ash.

[0015] Preferably, in step (2), the weight proportions of the raw materials in the mixture are: 100-120 parts of zinc-containing dust, 10-15 parts of biomass powder, 5-8 parts of calcium oxide, 20-25 parts of bentonite, 10-15 parts of tar residue powder, and 15-20 parts of calcium chloride solution;

[0016] The molar concentration of the calcium chloride solution is 1.5-2 mol / L.

[0017] Preferably, the ball making time in step (3) is 16 to 20 minutes, the moisture content of the raw balls is 13% to 15%, and the particle size of the raw balls is 10 to 16 mm.

[0018] Preferably, the drying temperature of the dry bulb in step (3) is 250-350° C., the drying wind speed is 0.6-1.4 m / s, and the drying time is 8-12 min.

[0019] Preferably, in step (4), the volume ratio of N2, H2 and CO in the mixed gas is 4-6:3-5:1-2.

[0020] Preferably, in step (4), the volume ratio of N2, H2 and CO in the mixed gas is 5:4:2.

[0021] Preferably, in step (4), the temperature of the high temperature reduction is 1000-1200° C., the time is 30-60 min, and the flow rate of the mixed gas is 40-50 L / min.

[0022] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a method for hydrogen-based reduction dezincification of zinc-containing dust, which has the following beneficial effects:

[0023] (1) The present invention determines the selection and proportion of each component in the mixed material, which can synergistically promote the dezincification of dust. Among them, biomass is used as a reducing agent, which has a large number of volatile components and can effectively enhance the reduction and removal effect of zinc in zinc-containing dust. It has a wide source, reduces environmental pollution, realizes the functionalization and resource utilization of solid waste, and reduces process processing costs. Calcium oxide can appropriately reduce the temperature of the reaction system, and react with SiO2 to form slag, inhibit the slag reaction between SiO2 and ZnO, promote the separation of zinc and iron, and ZnO is easily reduced to zinc and volatilized, thereby improving the dezincification rate and reducing the consumption of carbon reducing agents. Tar residue powder has good viscosity, has a bonding effect during ball making, strengthens the strength of the dry ball, and can also improve the dispersibility of various materials. After adding calcium chloride, zinc can form zinc chloride with a lower boiling point during the volatilization reaction, thereby improving the dezincification rate.

[0024] (2) The reducing atmosphere of the present invention is a mixed gas of H2 and CO, and the reduction dezincification effect is better than the reduction dezincification effect of a single reducing gas. By properly adjusting the ratio of H2 and CO, the metallization rate and dezincification rate of the reduction product can be effectively improved, which is suitable for large-scale factory application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for dezincification of zinc-containing dust by hydrogen-based reduction, comprising the following steps:

[0028] (1) drying the coconut shell, crushing it in a ball mill, and sieving it to obtain biomass powder;

[0029] (2) mixing electric furnace dust, biomass powder, calcium oxide, bentonite, tar residue powder, and calcium chloride solution uniformly to obtain a mixture;

[0030] (3) pelletizing the mixed material in a disc pelletizing machine to obtain green pellets, and then drying to obtain dry pellets;

[0031] (4) heating the dry ball to 500° C. in a protective atmosphere of N2, then introducing H2 and CO, heating it for a second time, and performing high-temperature reduction in a mixed gas. After the reduction is completed, the dry ball is cooled down under the protection of argon gas and cooled to room temperature to obtain dezincified reduced pellets;

[0032] The drying temperature in step (1) is 70° C. and the drying time is 0.5 h. After crushing, the powder is passed through a 100-mesh sieve.

[0033] In step (2), the weight proportions of the raw materials in the mixture are: 100 parts of electric furnace dust, 10 parts of coconut shell, 5 parts of calcium oxide, 20 parts of bentonite, 10 parts of tar residue powder, and 15 parts of calcium chloride solution;

[0034] The molar concentration of the calcium chloride solution is 1.5 mol / L;

[0035] The ball making time in step (3) is 16 minutes, the moisture content of the raw balls is 13%, and the particle size of the raw balls is 10 mm;

[0036] In step (3), the drying temperature of the dry bulb is 250° C., the drying wind speed is 0.6 m / s, and the drying time is 8 min.

[0037] In step (4), the volume ratio of N2, H2 and CO in the mixed gas is 4:3:1;

[0038] In step (4), the temperature of the high-temperature reduction is 1000° C., the time is 30 min, and the flow rate of the mixed gas is 40 L / min.

[0039] Example 2

[0040] A method for dezincification of zinc-containing dust by hydrogen-based reduction, comprising the following steps:

[0041] (1) drying the palm shell, crushing it in a ball mill, and sieving it to obtain biomass powder;

[0042] (2) mixing blast furnace ash, biomass powder, calcium oxide, bentonite, tar residue powder, and calcium chloride solution uniformly to obtain a mixture;

[0043] (3) pelletizing the mixed material in a disc pelletizing machine to obtain green pellets, and then drying to obtain dry pellets;

[0044] (4) heating the dry ball to 500° C. in a protective atmosphere of N2, then introducing H2 and CO, heating it for a second time, and performing high-temperature reduction in a mixed gas. After the reduction is completed, the dry ball is cooled down under the protection of argon gas and cooled to room temperature to obtain dezincified reduced pellets;

[0045] The drying temperature in step (1) is 80° C. for 2 h, and the powder is sieved through a 150-mesh sieve after being crushed.

[0046] In step (2), the weight proportions of the raw materials in the mixture are: 120 parts of blast furnace ash, 15 parts of biomass powder, 8 parts of calcium oxide, 25 parts of bentonite, 15 parts of tar residue powder, and 20 parts of calcium chloride solution;

[0047] The molar concentration of the calcium chloride solution is 2 mol / L;

[0048] The ball making time in step (3) is 20 minutes, the moisture content of the raw balls is 15%, and the particle size of the raw balls is 16 mm;

[0049] In step (3), the drying temperature of the dry bulb is 350° C., the drying wind speed is 1.4 m / s, and the drying time is 12 min;

[0050] In step (4), the volume ratio of N2, H2 and CO in the mixed gas is 6:5:2;

[0051] In step (4), the temperature of the high-temperature reduction is 1200° C., the time is 60 min, and the flow rate of the mixed gas is 50 L / min.

[0052] Example 3

[0053] A method for dezincification of zinc-containing dust by hydrogen-based reduction, comprising the following steps:

[0054] (1) drying the palm shell, crushing it in a ball mill, and sieving it to obtain biomass powder;

[0055] (2) mixing blast furnace ash, biomass powder, calcium oxide, bentonite, tar residue powder, and calcium chloride solution uniformly to obtain a mixture;

[0056] (3) pelletizing the mixed material in a disc pelletizing machine to obtain green pellets, and then drying to obtain dry pellets;

[0057] (4) heating the dry ball to 500° C. in a protective atmosphere of N2, then introducing H2 and CO, heating it for a second time, and performing high-temperature reduction in a mixed gas. After the reduction is completed, the dry ball is cooled down under the protection of argon gas and cooled to room temperature to obtain dezincified reduced pellets;

[0058] The drying temperature in step (1) is 75° C. and the drying time is 1 h. After crushing, the powder is passed through a 120-mesh sieve.

[0059] In step (2), the weight proportions of the raw materials in the mixture are: 110 parts of blast furnace ash, 12 parts of biomass powder, 6 parts of calcium oxide, 22 parts of bentonite, 12 parts of tar residue powder, and 18 parts of calcium chloride solution;

[0060] The molar concentration of the calcium chloride solution is 2 mol / L;

[0061] The ball making time in step (3) is 18 minutes, the moisture content of the raw balls is 14%, and the particle size of the raw balls is 14 mm;

[0062] In step (3), the drying temperature of the dry bulb is 300° C., the drying wind speed is 1.2 m / s, and the drying time is 10 min.

[0063] In step (4), the volume ratio of N2, H2 and CO in the mixed gas is 5:4:2;

[0064] In step (4), the temperature of the high-temperature reduction is 1100° C., the time is 40 min, and the flow rate of the mixed gas is 45 L / min.

[0065] Comparative Example 1

[0066] The difference from Example 3 is that no biomass powder is added, and the rest is the same. Zinc-removed reduced pellets are obtained.

[0067] Comparative Example 2

[0068] The difference from Example 3 is that calcium oxide and calcium chloride are not added, and the rest is the same. Dezincified reduced pellets are obtained.

[0069] Comparative Example 3

[0070] The difference from Example 3 is that in step (4), the volume ratio of N2 to H2 in the mixed gas is 5:6, and no CO is introduced. Dezincified reduced pellets are obtained.

[0071] Comparative Example 4

[0072] The difference from Example 3 is that in step (4), the volume ratio of N2 to CO in the mixed gas is 5:6, and H2 is not introduced. Dezincified reduced pellets are obtained.

[0073] The metallization rate and dezincification rate of each embodiment and comparative example are shown in Table 1. Analysis shows that the lack of key components such as biomass, calcium oxide or calcium chloride will affect the zinc-iron separation effect, resulting in a decrease in the dezincification rate. When the reducing atmosphere is a mixed gas of H2 and CO, the reduction dezincification effect is better than that of a single reducing gas H2 or CO. The reducibility of H2 is stronger than that of CO at high temperatures, and from a kinetic point of view, the mass transfer rate of H2 is also greater than that of CO, so the dezincification effect of comparative example 3 is better than that of comparative example 4. During the reaction process, the reduction of iron oxides begins at a relatively low temperature, at which time the reducibility of CO is relatively high, which will affect the metallization rate, so adjusting the ratio of CO and H2 in the reducing gas can increase the metallization rate. At the same time, since ZnO begins to be reduced and converted into zinc vapor at high temperatures, the reduction effect of H2 on ZnO is better than that of CO on ZnO at high temperatures, so maintaining a high ratio of H2 in the reducing gas can increase the dezincification rate of the zinc-containing dust reduction product. Finally, the appropriate ratio of H2 and CO was determined.

[0074] Table 1

[0075] Group Metallization rate % Zinc removal rate % Example 1 95.42 99.15 Example 2 96.31 99.32 Example 3 96.87 99.68 Comparative Example 1 90.69 93.65 Comparative Example 2 91.26 94.37 Comparative Example 3 93.85 97.04 Comparative Example 4 91.74 94.28

[0076] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the scheme disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0077] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for dezincification of zinc-containing dust by hydrogen-based reduction, characterized in that: The following steps are involved: (1) drying the biomass, crushing it in a ball mill, and sieving it to obtain biomass powder; (2) mixing zinc-containing dust, biomass powder, calcium oxide, bentonite, tar residue powder, and calcium chloride solution uniformly to obtain a mixture; (3) pelletizing the mixed material in a disc pelletizing machine to obtain green pellets, and then drying to obtain dry pellets; (4) The dry ball is heated to 500° C. under a protective atmosphere of N2, and then H2 and CO are introduced for secondary heating, and high-temperature reduction is carried out in the mixed gas. After the reduction is completed, the temperature is lowered under the protection of argon gas and cooled to room temperature to obtain dezincified reduced pellets.

2. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: The biomass in step (1) is selected from one or more of coconut shells, peanut shells, walnut shells, melon seed shells, palm shells, cocoa shells, bagasse, and traditional Chinese medicine residues.

3. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: The drying temperature in step (1) is 70-80° C., the drying time is 0.5-2 h, and the powder is sieved through a 100-150 mesh sieve after being crushed.

4. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: The zinc-containing dust in step (2) includes one or more of electric furnace dust, converter dust, iron oxide scale, blast furnace bag ash, and blast furnace gravity ash.

5. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: In step (2), the weight proportions of the raw materials in the mixture are: 100-120 parts of zinc-containing dust, 10-15 parts of biomass powder, 5-8 parts of calcium oxide, 20-25 parts of bentonite, 10-15 parts of tar residue powder, and 15-20 parts of calcium chloride solution; The molar concentration of the calcium chloride solution is 1.5-2 mol / L.

6. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: The ball making time in step (3) is 16 to 20 minutes, the moisture content of the raw balls is 13% to 15%, and the particle size of the raw balls is 10 to 16 mm.

7. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: The drying temperature of the dry bulb in step (3) is 250-350° C., the drying wind speed is 0.6-1.4 m / s, and the drying time is 8-12 min.

8. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: In step (4), the volume ratio of N2, H2 and CO in the mixed gas is 4-6:3-5:1-2.

9. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 8, characterized in that: In step (4), the volume ratio of N2, H2 and CO in the mixed gas is 5:4:

2.

10. The method for dezincification of zinc-containing dust by hydrogen-based reduction according to claim 1, characterized in that: In step (4), the temperature of the high temperature reduction is 1000-1200° C., the time is 30-60 min, and the flow rate of the mixed gas is 40-50 L / min.