CN111676377A - Method for recycling zinc powder in zinc-containing dust through cyclic enrichment of flash furnace - Google Patents
Method for recycling zinc powder in zinc-containing dust through cyclic enrichment of flash furnace Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/34—Obtaining zinc oxide
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/20—Obtaining zinc otherwise than by distilling
- C22B19/22—Obtaining zinc otherwise than by distilling with leaching with acids
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/30—Obtaining zinc or zinc oxide from metallic residues or scraps
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—Dry processes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
- C22B7/007—Wet processes by acid leaching
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention provides a method for recycling zinc powder in zinc-containing dust by circulating enrichment in a flash furnace. Firstly, quantitatively calculating the theoretical demand of a reducing agent by testing the element content in the zinc-containing dust; then, quantitatively adding zinc-containing dust and a reducing agent into the flash furnace according to the calculation result, and carrying out reduction smelting to obtain smoke containing zinc vapor and molten iron slag; after the smoke meets cold air, zinc vapor is oxidized into zinc oxide powder, solid powder in the smoke is separated from gas, the solid powder is circularly blown into a flash furnace, a reducing agent is supplemented as required, and the solid powder is subjected to wet leaching to obtain a high-purity zinc product when the content of zinc in the solid powder is more than or equal to 10%; and carrying out quick cooling, crushing and magnetic separation on the molten iron slag to obtain an iron raw material and a cement raw material. The invention improves the purity of the crude zinc oxide product by circulating enrichment and wet leaching of the flash furnace, thereby reducing the recovery energy consumption, the cost and the pollution to the environment and obviously improving the purity of the recovered zinc.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a method for recycling zinc powder in zinc-containing dust through cyclic enrichment of a flash furnace.
Background
Most of iron ores contain harmful elements such as zinc and lead, during iron making, the zinc and lead are reduced into gas-form simple substances at high temperature, the gas-form simple substances are carried out of the furnace together with dust such as ores, coke and flux along with flue gas, the gas-form simple substances are oxidized into zinc oxide and lead oxide after encountering air, and then the zinc-containing dust is collected by a dust removal and purification device. If the zinc-containing dust cannot be properly treated, a large amount of land is occupied, and meanwhile, the resource waste of valuable metals in the zinc-containing dust is caused, and potential safety hazards are brought to the environment. Therefore, the method has important significance for enriching and recovering the zinc powder in the zinc-containing dust.
At present, the method for recovering zinc powder in zinc-containing dust mainly adopts the pyrometallurgical enrichment or wet leaching collection or the combination of the pyrometallurgy and the wet method to carry out enrichment recovery. According to the pyrogenic enrichment, the characteristics that metal zinc is low in boiling point (907 ℃) and volatile are utilized, zinc oxide is reduced into zinc vapor and volatilized out in a high-temperature reducing atmosphere, the zinc vapor is enriched in a collector in a zinc oxide form after being secondarily oxidized in a flue, the recovery rate of zinc in the pyrogenic treatment of blast furnace dust is up to more than 85%, and the purity of the obtained zinc oxide is not high. The wet leaching is to utilize the characteristic that zinc oxide can be dissolved in acid or alkali, use acid or alkali solution as leaching solution to leach zinc in zinc-containing dust, and then use solvent extraction method or ion exchange method to recover zinc from the leaching solution. The wet method has the advantages of less pollution and less consumed energy. However, when sulfuric acid is used for leaching, not only zinc is leached, but also a large amount of iron in the gas ash enters the leachate, so that the subsequent purification of the leachate is difficult. When sodium hydroxide is used as a leaching agent, zinc in the leachate exists in the form of sodium zincate, which makes it difficult to electrolyze zinc in the subsequent process. And when the zinc-containing dust is directly leached by a wet method, the consumption of a leaching agent is high and the corrosion to equipment is serious due to low zinc content. In actual production, crude zinc oxide powder is generally obtained by pyrogenic enrichment and recovery, and then zinc oxide is leached by a wet method to obtain a zinc product with high purity.
However, the composition of the zinc-containing dust is affected by the types of metallurgical furnaces, the metallurgical manner, the content of zinc in iron ore and other factors, so that the content of zinc in the zinc-containing dust is different, and the content of zinc is generally between 0.01% and 30%, for example, the content of zinc in electric furnace dust is relatively high and is between 1% and 30%, while the content of zinc in blast furnace gas dust is only between 0% and 0.1%. The lower the zinc content in the zinc-containing dust is, the lower the zinc oxide content in the crude zinc oxide powder obtained by pyrogenic enrichment is, and a large amount of dust such as metal oxides of iron, lead and the like, calcium oxide, aluminum oxide, coal ash and the like can be contained, when the crude zinc oxide powder is extracted and purified by a wet method, a large amount of leaching agent still needs to be consumed, and the extraction purity is also greatly influenced.
Therefore, it is urgently needed to provide a method for recovering zinc powder from zinc-containing dust, so as to reduce the recovery energy consumption and cost, reduce the pollution to the environment and improve the purity of the recovered zinc.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for recycling zinc powder in zinc-containing dust by using a flash furnace in a circulating enrichment manner. Firstly, quantitatively calculating the theoretical demand of a reducing agent by testing the element content in the zinc-containing dust; then, quantitatively adding zinc-containing dust and a reducing agent into the flash furnace according to the calculation result, and carrying out reduction smelting to obtain smoke containing zinc vapor and molten iron slag; after the smoke meets cold air, oxidizing zinc vapor into zinc oxide, separating solid powder from gas in the smoke, circularly blowing the solid powder into the flash furnace until the content of zinc in the solid powder is more than or equal to 10%, recovering the solid powder, and purifying the solid powder to obtain a high-purity zinc product; and carrying out quick cooling, crushing and magnetic separation on the molten iron slag to obtain an iron raw material and a cement raw material.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for recycling zinc powder in zinc-containing dust through cyclic enrichment of a flash furnace comprises the following steps:
s1, taking zinc-containing dust to be recovered, testing the element content of the zinc-containing dust, and then calculating the theoretical demand of a reducing agent during reduction smelting;
s2, according to the theoretical demand of the reducing agent obtained in the step S1, uniformly mixing the zinc-containing dust and the reducing agent, and then putting the mixture into a flash furnace for reduction smelting to obtain flue gas and molten iron slag;
the flue gas comprises zinc vapor and other gases and dust, and the molten iron slag comprises valuable metals and other components;
s3, collecting the flue gas obtained in the step S2, oxidizing zinc vapor in the flue gas into zinc oxide powder after meeting air to obtain solid powder and other gases, separating the solid powder from the other gases, and discharging the gases outside; detecting the content of zinc oxide in the solid powder at regular time, if the content of the zinc oxide is less than 10%, circularly blowing the solid powder into a flash furnace, calculating the amount of a reducing agent to be supplemented according to the content of zinc oxide and iron oxide in the solid powder, and when the content of the zinc oxide is more than or equal to 10%, not circularly blowing the solid powder into the flash furnace any more, and purifying the solid powder to obtain a high-purity zinc product;
and S4, collecting the molten slag iron remained in the flash furnace in the step S2, and obtaining magnetic metal iron materials and nonmagnetic slag through quick cooling, crushing and magnetic separation, wherein the iron materials are collected as follow-up steelmaking raw materials, and the slag is collected as a cement raw material.
Further, selecting a plurality of groups of zinc-containing dust to be recovered with different zinc contents and the same quality, repeating the steps S1-S4, recording the reduction smelting time as ti when the i-th group of zinc-containing dust to be recovered is subjected to reduction smelting, and obtaining the relation between the zinc content W in the zinc-containing dust and the cyclic enrichment time ti through curve fitting when the zinc oxide content in the solid powder is more than or equal to 10%, so that the cyclic enrichment time is quickly determined according to the element content of the zinc-containing dust to reduce the detection of the zinc oxide content in the solid powder;
wherein i is a positive integer not less than 4, and ti is a positive integer.
Further, in step S1, the theoretical requirement of the reducing agent is calculated according to the contents of zinc oxide and iron oxide in the zinc-containing dust.
Further, the reducing agent is coke powder or coal powder or a mixture of the coke powder and the coal powder.
Further, in step S2, the temperature of the reduction smelting is 1050-1650 ℃.
Further, in step S3, the time interval of the timing detection is 5-30 min.
Further, in step S3, the solid powder and other gases are separated by a cyclone.
Further, in step S3, the solid powder is circularly blown into the flash furnace together with the preheated air from the tuyere of the flash furnace.
Further, in step S3, the solid powder is purified by wet enrichment to obtain a high-purity zinc product.
Further, the solid powder is purified by an acid leaching method to obtain a high-purity zinc product.
Advantageous effects
Compared with the prior art, the method for circularly enriching and recovering zinc powder in zinc-containing dust by the flash furnace has the following beneficial effects:
(1) the method for recycling zinc powder in zinc-containing dust through cyclic enrichment of the flash furnace comprises the steps of firstly, testing the content of elements in the zinc-containing dust, and quantitatively calculating the theoretical demand of a reducing agent; then, quantitatively adding zinc-containing dust and a reducing agent into the flash furnace according to the calculation result, and carrying out reduction smelting to obtain smoke containing zinc vapor and molten iron slag; after the smoke meets cold air, zinc vapor is oxidized into zinc oxide powder, solid powder in the smoke is separated from gas, the solid powder is circularly blown into a flash furnace, a reducing agent is supplemented as required, and the solid powder is subjected to wet leaching to obtain a high-purity zinc product when the content of zinc in the solid powder is more than or equal to 10%; and carrying out quick cooling, crushing and magnetic separation on the molten iron slag to obtain an iron raw material and a cement raw material. According to the scheme, the zinc-containing dust is subjected to flash furnace cyclic enrichment and wet leaching, so that the purity of a crude zinc oxide product is improved, the consumption of a leaching agent in the wet leaching is reduced, the leaching efficiency and the purity are improved, the recovery energy consumption, the recovery cost and the pollution to the environment are obviously reduced, and the purity of recovered zinc is obviously improved.
(2) The invention carries out circulating injection and multiple times of reduction smelting on the solid powder generated by the reduction smelting of the flash furnace, continuously improves the content of zinc oxide in the solid powder, reduces the content of dust of other valuable metals and the like in the solid powder, and carries out wet leaching on the solid powder to obtain a high-purity zinc product when the content of zinc in the solid powder is more than or equal to 10 percent.
(3) The invention quantitatively calculates the theoretical demand of the reducing agent during reduction smelting by performing element detection on the zinc-containing dust and the solid powder obtained by reduction smelting according to the thermodynamics and kinetics principles of the reduction smelting, and quantitatively adds the reducing agent and the zinc-containing dust into the flash furnace according to the calculation result, thereby utilizing the reducing agent to the maximum extent, reducing the waste of the reducing agent, saving the cost, improving the energy consumption utilization rate, reducing and recovering the zinc oxide in the zinc-containing dust to the maximum extent and improving the recovery rate of zinc.
(4) By adopting the method for recycling zinc powder in zinc-containing dust through cyclic enrichment, provided by the invention, a plurality of groups of zinc-containing dust to be recycled with different zinc contents and the same quality are recycled through cyclic enrichment, and the cyclic enrichment time is respectively obtained when the zinc oxide content in the solid powder is more than or equal to 10% during cyclic enrichment of the zinc-containing dust; by curve fitting, the relation between the zinc content in the zinc-containing dust and the cyclic enrichment time can be obtained, so that the cyclic enrichment time can be quickly determined according to the element content of the zinc-containing dust, the detection on the zinc oxide content in the solid powder is reduced, and the zinc-containing dust can be recovered under the optimal cyclic enrichment condition.
(5) The invention adopts the flash furnace to carry out pyrogenic cycle enrichment on the zinc-containing dust, the flash furnace is a smelting furnace for strengthening production, the zinc-containing dust with ultrahigh surface area is fully contacted with a reducing agent in the furnace, the reduction smelting reaction of metal oxides is completed at an extremely high speed at high temperature, and the flash furnace has the characteristics of high production rate, low energy consumption and high concentration of zinc oxide in flue gas, thereby obviously improving the recovery rate and purity of zinc.
Drawings
FIG. 1 is a flow chart of a method for recycling zinc powder in zinc-containing dust by circulating enrichment of a flash furnace provided by the invention;
FIG. 2 is a graph showing the relationship between the zinc oxide content in the solid powder and the purity of the zinc product obtained by acid leaching according to the cycle enrichment time in example 1;
FIG. 3 is a graph of the zinc oxide content of the solid powder and the purity of the zinc product from acid leaching versus cycle enrichment time in example 2;
FIG. 4 is a graph of the cycle enrichment time versus the zinc oxide content of the zinc containing dust obtained in examples 1 to 4.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
Referring to fig. 1, the present invention provides a method for recycling zinc dust in a flash furnace by recycling, enriching and recovering zinc dust, comprising the following steps:
s1, taking zinc-containing dust to be recovered, testing the element content of the zinc-containing dust, and then calculating the theoretical demand of a reducing agent during reduction smelting.
The theoretical demand of the reducing agent is calculated according to the contents of zinc oxide and iron oxide in the zinc-containing dust.
Preferably, the reducing agent is coke powder or coal powder or a mixture of the coke powder and the coal powder.
During the reduction smelting of zinc-containing dust, the substances subjected to reduction reaction are mainly oxides of zinc and iron, and the theoretical demand of the reducing agent is generally calculated according to the following reaction formula:
ZnO(s)+C(g)＝Zn(g)+CO(g)
3Fe2O3(s)+C(g)＝2Fe3O4(s)+CO(g)
Fe3O4(s)+C(g)＝3FeO(s)+CO(g)
FeO(s)+C(g)＝Fe(s)+CO(g)
when the content of zinc and iron elements in the zinc-containing dust is measured, the theoretical demand of the reducing agent can be calculated according to the chemical reaction formula. According to the invention, the theoretical demand of the reducing agent during reduction smelting is quantitatively calculated according to the thermodynamics and kinetics principles of reduction smelting, and the reducing agent and the zinc-containing dust are quantitatively put into the flash furnace according to the calculation result, so that the reducing agent is utilized to the maximum extent, the waste of the reducing agent is reduced, the cost is saved, the energy consumption utilization rate can be improved, the zinc oxide in the zinc-containing dust is reduced and recovered to the maximum extent, and the recovery rate of zinc is improved.
S2, according to the theoretical demand of the reducing agent obtained in the step S1, uniformly mixing the zinc-containing dust and the reducing agent, then putting the mixture into a flash furnace, and carrying out reduction smelting at 1050-1650 ℃ to obtain flue gas and molten iron slag.
The flue gas includes zinc vapor and other gases and dust, and the molten iron slag includes valuable metals and other constituents. The boiling point of zinc is 907 ℃, so that zinc is volatilized from a flue of the flash furnace in the form of zinc vapor at 1050-1650 ℃, and part of dust such as iron and other metal oxide powder and coal ash can be carried out together in the process.
S3, collecting the flue gas obtained in the step S2, introducing zinc vapor in the flue gas into air, oxidizing the zinc vapor into zinc oxide powder to obtain solid powder and other gases, separating the solid powder from the other gases, and discharging the gases outside; and detecting the content of zinc oxide in the solid powder at regular time, if the content of the zinc oxide is less than 10%, circularly blowing the solid powder into the flash furnace, calculating the amount of a reducing agent to be supplemented according to the content of zinc oxide and iron oxide in the solid powder, and when the content of the zinc oxide is more than or equal to 10%, not circularly blowing the solid powder into the flash furnace any more, and purifying the solid powder to obtain a high-purity zinc product.
Preferably, the time interval of the timing detection is 5-30 min.
Further, the solid powder and other gases are separated by a cyclone. Separating the solids from the gas reduces the impurity level and thus increases the zinc level in steps.
Further, the solid powder is circularly blown into the flash furnace together with preheated air from a tuyere of the flash furnace. The zinc powder is circularly blown into the flash furnace together with hot air, so that the reduction smelting efficiency is improved, the zinc in the solid powder is continuously enriched, and the purity of the crude zinc oxide is improved.
Further, the solid powder is purified by a wet enrichment method to obtain a high-purity zinc product.
Preferably, the solid powder is purified by acid leaching to obtain a high-purity zinc product.
And S4, collecting the molten slag iron remained in the flash furnace in the step S2, and obtaining magnetic metal iron materials and nonmagnetic slag through quick cooling, crushing and magnetic separation, wherein the iron materials are collected as follow-up steelmaking raw materials, and the slag is collected as a cement raw material.
Further, selecting a plurality of groups of zinc-containing dust to be recovered with the same mass and different zinc contents, repeating the steps from S1 to S4, and recording the cyclic enrichment time as t when the content of zinc oxide in the solid powder is more than or equal to 10% when the ith group of zinc-containing dust to be recovered is subjected to reduction smeltingiObtaining the zinc content W and the cyclic enrichment time t in the zinc-containing dust through curve fittingiThereby rapidly determining the cyclic enrichment time according to the element content of the zinc-containing dust so as to reduce the detection of the zinc oxide content in the solid powder;
wherein i is a positive integer not less than 4, tiIs a positive integer.
In general, the higher the zinc content W in the zinc-containing dust, the higher the cycle enrichment time tiThe smaller, i.e. the cycle enrichment time tiIs inversely related to the content W of the zinc-containing dust. The cyclic enrichment time is the time from the beginning of reduction smelting to the time when the content of zinc oxide in the solid powder produced by the reduction smelting is more than or equal to 10 percent. Due to generation ofThe solid powder of (2) is continuously introduced into the flash furnace, and therefore it is not convenient to define the degree of cyclic enrichment in terms of the number of cycles. When the mass of the zinc-containing dust obtained by the initial reduction smelting is constant, the longer the cyclic enrichment time is, the lower the zinc content in the zinc-containing dust is.
Example 1
A method for recycling zinc powder in zinc-containing dust by cyclic enrichment of a flash furnace is used for cyclic enrichment and recycling of zinc-containing dust generated in blast furnace ironmaking in an iron plant, and comprises the following steps:
TABLE 1 Zinc-containing dust chemical composition by mass
S1, taking 1t of the zinc-containing dust, testing the element content of the zinc-containing dust, and calculating the theoretical demand of a reducing agent during reduction smelting according to the following formula as shown in Table 1:
ZnO(s)+C(g)＝Zn(g)+CO(g)
3Fe2O3(s)+C(g)＝2Fe3O4(s)+CO(g)
Fe3O4(s)+C(g)＝3FeO(s)+CO(g)
FeO(s)+C(g)＝Fe(s)+CO(g)
the mass of zinc oxide in 1t of the zinc-containing dust is 95.2kg, the mass of iron oxide is 205.5kg, the mass of ferrous oxide is 130.8kg, the zinc oxide is converted into the amount of substances, then according to the metering ratio of the chemical reaction formula, the required amount of the reducing agent in 1t of the zinc-containing dust is 82.21kg, and the carbon content in 1t of the zinc-containing dust is 300.1kg, which is far more than the theoretical required amount, so that the reducing agent does not need to be supplemented during the initial reduction smelting.
S2, putting the zinc-containing dust into a flash furnace, and carrying out reduction smelting at 1350 ℃ to obtain smoke and molten iron slag;
the flue gas comprises zinc vapor and other gases and dust, and the molten iron slag comprises valuable metals and other components;
s3, collecting the flue gas obtained in the step S2, oxidizing zinc vapor in the flue gas into zinc oxide powder after encountering cold air to obtain solid powder and other gases, separating the solid powder from the other gases through a cyclone separator, and discharging the gases outside; taking generated solid powder at regular time at intervals of 10min, testing the element content of the solid powder, if the content of zinc oxide is less than 10 wt%, circularly blowing the solid powder into a flash furnace from a tuyere of the flash furnace along with preheated air, calculating the amount of a reducing agent to be supplemented according to the content of zinc oxide and iron oxide in the solid powder, and when the content of zinc oxide is more than or equal to 10%, not circularly blowing the solid powder into the flash furnace any more, and performing acid leaching purification on the solid powder to obtain a zinc product with the purity of more than 99.8%;
as shown in fig. 2, which is a graph of the content of zinc oxide in the solid powder and the purity of the zinc product obtained by acid leaching as a function of the cyclic enrichment time, it can be seen that the content of zinc oxide in the solid powder gradually increases as the cyclic enrichment time is prolonged. It is shown that the content of zinc oxide in the solid powder can be increased by the cyclic enrichment, and the purity of zinc obtained by acid leaching is further improved.
And S4, collecting the molten slag iron left in the flash furnace in the step S2, and quickly cooling, crushing and magnetically separating to obtain magnetic substances and nonmagnetic substances, wherein the magnetic substances are collected as iron raw materials, and the nonmagnetic substances are collected as cement raw materials.
Example 2
A method for recycling zinc powder in zinc-containing dust by cyclic enrichment of a flash furnace is used for cyclic enrichment and recycling of zinc-containing dust generated in iron making of an electric furnace in an iron plant, and comprises the following steps:
TABLE 2 Zinc-containing dust chemical composition by mass
S1, taking 1t of the zinc-containing dust, testing the element content of the zinc-containing dust, and calculating the theoretical demand of a reducing agent during reduction smelting according to the following formula as shown in Table 2:
ZnO(s)+C(g)＝Zn(g)+CO(g)
3Fe2O3(s)+C(g)＝2Fe3O4(s)+CO(g)
Fe3O4(s)+C(g)＝3FeO(s)+CO(g)
FeO(s)+C(g)＝Fe(s)+CO(g)
the mass of zinc oxide in 1t of the zinc-containing dust is 89.9kg, the mass of iron oxide is 367.6kg, the mass of ferrous oxide is 180.8kg, the zinc oxide and the ferrous oxide are converted into the amount of substances, and then according to the stoichiometric ratio of the chemical reaction formula, the required amount of a reducing agent in 1t of the zinc-containing dust is 126.27kg, and the carbon content in 1t of the zinc-containing dust is 93.3kg, so 32.97kg of coke needs to be supplemented during initial reduction smelting.
S2, uniformly mixing the zinc-containing dust and coke, putting the mixture into a flash furnace, and carrying out reduction smelting at 1200 ℃ to obtain smoke and molten iron slag;
the flue gas comprises zinc vapor and other gases and dust, and the molten iron slag comprises valuable metals and other components;
s3, collecting the flue gas obtained in the step S2, oxidizing zinc vapor in the flue gas into zinc oxide powder after encountering cold air to obtain solid powder and other gases, separating the solid powder from the other gases through a cyclone separator, and discharging the gases outside; taking generated solid powder at regular time at intervals of 5min, testing the element content of the solid powder, if the content of zinc oxide is less than 10 wt%, circularly blowing the solid powder into a flash furnace from a tuyere of the flash furnace along with preheated air, calculating the amount of coke required to be supplemented according to the content of zinc oxide and iron oxide in the solid powder, supplementing the coke according to the requirement, and when the content of zinc oxide is more than or equal to 10%, not circularly blowing the solid powder into the flash furnace any more, and performing acid leaching purification on the solid powder to obtain a zinc product with the purity of more than 99.8%;
as shown in fig. 3, which is a graph of the content of zinc oxide in the solid powder and the purity of the zinc product obtained by acid leaching as a function of the cyclic enrichment time, it can be seen that the content of zinc oxide in the solid powder gradually increases as the cyclic enrichment time is prolonged. It is shown that the content of zinc oxide in the solid powder can be increased by the cyclic enrichment, and the purity of zinc obtained by acid leaching is further improved. The cycle enrichment time of example 2 was shortened by about 25min compared to example 1, indicating that the cycle enrichment time decreased as the zinc content in the zinc-containing dust increased.
And S4, collecting the molten slag iron left in the flash furnace in the step S2, and quickly cooling, crushing and magnetically separating to obtain magnetic substances and nonmagnetic substances, wherein the magnetic substances are collected as iron raw materials, and the nonmagnetic substances are collected as cement raw materials.
Example 3
Example 3 is different from example 1 in that the composition of the zinc-containing dust to be recovered is shown in table 3, and the recovery processing steps are substantially the same as those of example 1, and are not described again.
TABLE 3 Zinc-containing dust chemical composition by mass
After cyclic enrichment recovery, the cyclic enrichment time is about 80min when the content of zinc oxide in the obtained solid powder is more than or equal to 10 percent, which is increased compared with that of the embodiment 1.
Example 4
Example 4 is different from example 1 in that the composition of the zinc-containing dust to be recovered is shown in table 4, and the recovery processing steps are substantially the same as those of example 1, and are not described again.
TABLE 4 Zinc-containing dust chemical composition by mass
After cyclic enrichment recovery, the cyclic enrichment time is about 110min when the content of zinc oxide in the obtained solid powder is more than or equal to 10%, which is increased compared with that of the solid powder in the embodiment 1 and the embodiment 3. The zinc content in the zinc-containing dust is reduced, and the circulating enrichment time is prolonged.
As shown in fig. 4, it can be seen that the cyclic enrichment time t is inversely related to the content of zinc oxide in the zinc-containing dust, and the cyclic enrichment time gradually decreases as the content of zinc oxide in the zinc-containing dust increases. By curve fitting of the graph 4, the relation between the zinc-containing dust with the zinc oxide content of 0.01% -30% and the cyclic enrichment time can be further obtained, so that the cyclic enrichment time can be rapidly determined according to the element content of the zinc-containing dust, and the detection of the zinc oxide content in the solid powder can be reduced.
In conclusion, by adopting the scheme, the zinc-containing dust is subjected to flash furnace cyclic enrichment and wet leaching, so that the purity of a crude zinc oxide product is improved, the consumption of a leaching agent in the wet leaching is reduced, the leaching efficiency and the purity are improved, the recovery energy consumption, the recovery cost and the pollution to the environment are obviously reduced, and the purity of recovered zinc is obviously improved. Moreover, the relation between the zinc oxide content in the zinc-containing dust and the cyclic enrichment time can be roughly obtained, guidance is provided for the cyclic enrichment of the zinc-containing dust, and the cyclic enrichment time, energy consumption and cost are reduced.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (10)
1. A method for circularly enriching and recovering zinc powder in zinc-containing dust by a flash furnace is characterized by comprising the following steps:
s1, taking zinc-containing dust to be recovered, testing the element content of the zinc-containing dust, and then calculating the theoretical demand of a reducing agent during reduction smelting;
s2, according to the theoretical demand of the reducing agent obtained in the step S1, uniformly mixing the zinc-containing dust and the reducing agent, and then putting the mixture into a flash furnace for reduction smelting to obtain flue gas and molten iron slag;
the flue gas comprises zinc vapor and other gases and dust, and the molten iron slag comprises valuable metals and other components;
s3, collecting the flue gas obtained in the step S2, oxidizing zinc vapor in the flue gas into zinc oxide powder after meeting air to obtain solid powder and other gases, separating the solid powder from the other gases, and discharging the gases outside; detecting the content of zinc oxide in the solid powder at regular time, if the content of the zinc oxide is less than 10%, circularly blowing the solid powder into a flash furnace, calculating the amount of a reducing agent to be supplemented according to the content of zinc oxide and iron oxide in the solid powder, and when the content of the zinc oxide is more than or equal to 10%, not circularly blowing the solid powder into the flash furnace any more, and purifying the solid powder to obtain a high-purity zinc product;
and S4, collecting the molten slag iron remained in the flash furnace in the step S2, and obtaining magnetic metal iron materials and nonmagnetic slag through quick cooling, crushing and magnetic separation, wherein the iron materials are collected as follow-up steelmaking raw materials, and the slag is collected as a cement raw material.
2. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment as claimed in claim 1, wherein a plurality of groups of zinc-containing dust to be recycled with different zinc contents are selected, the steps S1 to S4 are repeated, and when the group i of zinc-containing dust to be recycled is subjected to reduction smelting, the reduction smelting time when the content of zinc oxide in solid powder is more than or equal to 10% is recorded as tiObtaining the zinc content W and the cyclic enrichment time t in the zinc-containing dust through curve fittingiThereby rapidly determining the cyclic enrichment time according to the element content of the zinc-containing dust so as to reduce the detection of the zinc oxide content in the solid powder;
wherein i is a positive integer not less than 4, tiIs a positive integer.
3. The method for recycling zinc dust in a flash furnace for enriching and recovering zinc dust according to claim 1, wherein the theoretical demand of the reducing agent is calculated according to the contents of zinc oxide and iron oxide in the zinc dust in step S1.
4. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment according to claim 3, characterized in that the reducing agent is coke powder or coal powder or a mixture of the coke powder and the coal powder.
5. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling and enriching as claimed in claim 1, wherein the temperature of the reduction smelting is 1050-1650 ℃ in step S2.
6. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment as claimed in claim 1, wherein the time interval of the timing detection in step S3 is 5-30 min.
7. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment as claimed in claim 1, characterized in that in step S3, the solid powder and other gases are separated through a cyclone separator.
8. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment according to claim 1, characterized in that in step S3, the solid powder is recycled and blown into the flash furnace from the flash furnace tuyere along with preheated air.
9. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment as claimed in claim 1, wherein in step S3, the solid powder is purified by a wet enrichment method to obtain a high-purity zinc product.
10. The method for recycling zinc powder in zinc-containing dust through flash furnace recycling enrichment as claimed in claim 1, characterized in that the solid powder is purified by acid leaching to obtain high-purity zinc product.
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