TWI241348B - Process for recovery of zinc and iron from EAF dust by reduction - Google Patents

Abstract

A new method is invented to recovery the metals zinc and iron from the EAF (electric arc furnace) dust. The main process is reduction with carbon monoxide gas as reduction agent after a pre-treatment. The EAF dust is first pelletized by adding water. The raw pellets are fed into the pre-treatment stage under oxidizing condition to vaporize the chlorides and lead compounds. The pellets free of chlorides and lead undergo then the reduction in carbon monoxide gas flow. After the full reduction, zinc oxide and iron oxide are fully reduced to their metallic form. Zinc, due to its low boiling point, is vaporized and carried out by the reaction gas flow. The obtaining of metallic zinc can be achieved in a condenser. The residue is iron sponge. After cooling, it can be re-used as raw material in iron metallurgy. This new process solves not only the long term problem of high chlorides/lead contents in EAF dust, but also provides the nearly full recycling of EAF dust by mean of winning the reusable zinc and iron in their metallic form.

Description

1241348 V. Description of the invention (l) [The invention to which the invention belongs is a square metal treatment of valuable metals, and two iron resources [prior art] Since 2001, it has been an electric solitary furnace in the south. Or alloy. To the ground, within the agitated gas zone under the condition of warm iron smelting. After stirring, it will react with zinc in compounds such as halogenated compounds. In addition to the oxide form-case number 93105475 [Technical Field] = Off 2 ^ Recycling dust contained in the dust collection ash of the electric arc furnace steel industry refers to the recovery of the pre-treated dust collection ash 〇Carbon gas is used as a reducing agent, and the steel obtained in the metallic zinc bay has been brought into electricity in the recent years. After the source is recovered, the number of steel arc furnaces is reduced due to the volatilization of the pieces. The shape and slope of the pieces are reduced. The amount of dust collected by the dust collector is the tenth most important furnace conditioning in the world. Even after the dust collection process in the atmospheric environment, molten iron is still formed into mixed oxygen compounds, which are also in metals such as fierce and ash. The elemental elements, electricity, and ring are made into anti-clockwise increase, and are used to collect drops and less. A dust collection ash magnesium, copper arc furnace technology long scrap scrap steel has increased in different quality examples, the phase is more than 5 noon 'in the south from the spray into the furnace, the dust collection ash part of the iron steam some volatile applications, etc. 'It can also be divided into the following table ...

1241348 _Case No. 93105475_Year Month Date_ V. Description of the invention (2) Element weight percentage [%] Zinc 20-30 Iron 25-40 Lead 2-4.0 Na 03-2.3 Potassium 0.1-20 Gas 0.5-2.5 氤 0.1- 03 Magnesium 0.5-1.5 Manganese 25-46 Copper 02-0.8 The melting and boiling points of the main compounds in the zinc-containing dust collection ash of the electric arc furnace are shown in Table 2 below:

Page 8 1241348 _____ Case No. 93105475 _ Amendment V. Description of the Invention (3) Compound Melting Point [. C] Boiling point [° C] Zinc iron spinel ZnFe2〇4 1590 — Zinc oxide Zπ〇1975 — Gas NaCl 801 1413 Potassium chloride κα 770 1500 Lead vaporized PbCl2 501 950 Oxygen PbO 886 — Electric 5 melon furnace set The crystalline composition of dust is closely related to the zinc-iron ratio. When the zinc-iron ratio is lower than about 0.58, the two metals exist as insoluble iron spinel or mixed phase (ZnxFe3_x〇4, 〇 < χ $ 1), with the increase of zinc content, 'excess zinc exists in the form of soluble zinc oxide. As far as the current operating conditions of the electric fox furnace steelmaking industry in Taiwan are concerned, the dust collection ash contains about 200 /. In the advanced European and American countries such as Germany, due to the improvement of the operating conditions of the electric arc furnace and the sharp increase in the galvanization rate of steel products, the content of zinc in the arc furnace dust ash has reached 30% or more. Compared with zinc ore, it is actually a high content of resources. Moreover, because zinc oxide has a high solubility, it can be taken out and recovered by dipping method. On the contrary, the solubility of zinc iron spinel and its mixed crystals is quite low. In order to achieve a high recovery rate of zinc, the core of the problem lies in the right attack to break down the insoluble zinc iron spinel. So far, the technologies used to recover the dust collected from the electric arc furnace can be divided into two categories: house chemistry and high temperature smelting technology:

1241348 V. Description of the invention (4) A. f = chemical technology, the application of the acidic or alkaline dissolution characteristics of zinc, and the destruction of zinc iron spinel with strong acid and alkali, although high purity zinc can be obtained after electrolysis, but Subsequent wastewater and waste acid, alkali problems, consumption of a large number of chemicals and low recovery rates have been obstacles to the promotion of such technologies; further, if the residue is to be returned to the furnace, the zinc content in the residue must be reduced to a certain level Below the level to avoid the negative effect of blocking the furnace body due to the formation of zinc blocks, and the impregnation residues generated by wet chemical technology; check, due to the insoluble zinc iron tip; the stone still contains zinc, so the residue The vocabulary is usually much higher than this limit. In addition, there are other methods that use weak acidic conditions to recover only the free oxidation part, and then mix the impregnated residue containing spinel into cement products for building materials and other uses. The recovery rate of such methods is about 85. % To 90%, iron is completely formed after immersion, it is discarded or used for building materials. B · WayU / rocess is the most widely used of the two-suit technology. This method is based on traditional high-temperature smelting technology and uses coke reduction method to recover zinc at a temperature exceeding 1 200 ° C. The main reactor is a rotary kiln. The biggest disadvantage is that the recovered crude oxidant contains the osmium chloride salt, which not only affects the subsequent dust collection facilities, reduces the purity and price, but also causes the crude zinc oxide produced to be unreliable to zinc smelters. X, if you want to meet the needs of zinc smelters, you need to increase the cost for the trip type = secondary treatment; In addition, in order to avoid the problem of the second and third place of the furnace caused by the high temperature melting of iron, a large amount of quartz must be added to the rotary kiln technology Absence of sand: = formation agent's implementation: one reduces the productivity of the process; the iron-containing slag can only be used for low-level uses such as subgrade construction and grading, and it is a waste of high economic resources and material . ^ ^ For the above reasons, in view of the lack of current recycling technology, it is 1241348 Case No. 93105475 _ Month Amendment _ V. Description of the invention (5) Effectively fully resource valuable materials without the fear of secondary pollution The goal is to specifically develop the present invention by the present inventors. According to the process of the present invention, the zinc and iron metals with the highest content in the dust collection ash of the electric arc furnace can be obtained in a high-value and high-purity metal state after pretreatment and reduction treatment, respectively, and the processing temperature is reduced to 1 Below 0 0 0 ° c, not only can save energy, but also effectively increase output value and save investment costs. [Summary of the Invention] In the traditional high-temperature treatment method based on a single reduction step, the reducing agent used is mostly solid coke, and it is also an energy source for supplying the thermal energy required for the reaction. Therefore, a large amount of combustion-supporting air must be introduced during the processing; At a reaction temperature above 1 200 ° C, components with low boiling points, such as halide salts and lead compounds, will first volatilize into the gas phase environment; in a reducing atmosphere, oxidants and iron oxides will be reduced to metal states, respectively. After evaporating into the air stream, the low-boiling metal zinc is oxidized again by oxygen in the air and carbon dioxide generated by combustion. Finally, it is cooled with salt and lead compounds and collected by dust removal equipment. In order to solve the subsequent problems of low product purity and the final disposal of iron-containing slag in the traditional way, the present inventors used carbon monoxide gas as a reducing agent and a pre-calcination treatment step. The present invention not only can effectively solve the traditional high-temperature smelting The shortcomings of the technology can also achieve the results of high recovery, high purity and low pollution, and can effectively avoid the disadvantages of wet smelting technology. The reduction reaction of zinc-iron spinel with carbon monoxide as a reducing agent will achieve different equilibrium crystal phases due to different temperatures. Therefore, temperature not only affects the chemical thermodynamic equilibrium of the reduction reaction itself, but also affects monoxide.

Page 11 Ϊ241348 ___ Case No. 93105475 V. Description of Invention (6)

B oud reaction equilibrium between carbon and carbon dioxide, and the ratio of carbon dioxide to dioxide in the reducing gas, as detailed below: (1) Reduction reaction of zinc iron spinel Generally speaking, zinc iron spinel The reduction reaction can be based on the reduction conditions, # the supply of carbon monoxide, to achieve a different j dna equilibrium state as shown in the following formulas (1) to (4):

ZnFe2O4 + 0.33CO <-> ZnO + 0.67Fe3〇4 + 〇.33C〇2 (i) ZnFe2〇4 + CO — > ZnO + 2FeO + C02 (2) ZnFe2〇4 + 3C〇 --- ZnO + 2Fe + 3C02 (3) ZnFe204 + 4C〇 <-> Zn + 2Fe + 4C02 (4) Because reaction products will form mixed crystals due to temperature, so-called solid solutions, so the equilibrium under actual conditions The phase is usually unavailable, and the above-mentioned pure crystal phase exists; it is possible to continue the solid solution formation reaction (formulas (5) and (6)) after the above reaction: (4) xZnO-f l ^ Fe304 + I x02 ZnxFe3.x04 (5) 3 6 xZn〇 + (l-WFeO ㈠ ZruFehO (6) where the oxygen required by formula 'C 5' can be supplied by carbon dioxide, and the mixed crystal constant X of the low zinc spinel formed is between 〇. Between 1. The zinc-ferrous halide formed by formula (6) has a so-called mixed gap, and the mixed crystal and

1241348 _Case No. 93105475_Year Month Day_Amendment V. Description of the Invention (7) The number X only falls in two different intervals 0 < x < 0.2 and 0.85 < χ < 1. The iron ratios are different, respectively, zinc-containing ferrous oxide and iron-containing zinc oxide; the ferrous oxide of the reactant can also be replaced by metallic iron, and the resulting mixed crystal is iron-containing zinc oxide. Therefore, under partial reduction conditions (that is, formulas (1) to (3)), zinc and iron still exist in a combined phase, and then are fully reduced to a metal state (ie, formula (4)) To achieve the ultimate goal of complete separation. For the phase states mentioned above, please refer to the "Zinc-Iron-Oxygen Ternary System Phase Diagram" in Annex I. It can be clearly shown that the radial arrow from the top to the bottom with the oxygen origin as the center is the direction of the reduction reaction. With the increase in the supply of double monoxide (ie, reducing the partial pressure of oxygen in the atmosphere of the system), the phase stability zone is sequentially reduced to the third / fourth zone (Area dish / IV, as in equation (1)) and the fifth / Six area (Area V / VI, as shown in equations (2) and (3)), and the phase stable region after full reduction shown in equation (4) falls on the Zn-Fe axis. (B) Boudouard reaction: Bouudouard & should be the exchange of oxygen 4 dagger charcoal and 2 1 oxygen 4 dagger charcoal at high temperature The reaction formula is as follows: 2CO (g) <-^ C〇2 (g ) + C (S) + 172.58 kJ / m ole (7) As this reaction involves changes in gas volume and endothermic / exothermic reactions, the effect of temperature is quite large; at temperatures above 100 ° C, the reaction is in equilibrium ^ Carbon monoxide, the content of which is about 99% by volume of the mixed gas, the reduction force is high; when the temperature drops to 40 0Λ :, the mixed gas contains more than 99% of the two gas ^ dagger carbon, the reduction reaction is mainly from solid carbon Be responsible for. This reaction formula has indicated that the heat is in a scientific equilibrium state, and according to the kinetic judgment, it is still thick in the reaction zone.

1241348 Case No. 93105475_Year Month Day Amendment V. Description of the invention (8) The concentration of monoxide bite in the stream will be closely related to the distance from the air inlet to the reaction zone, the heating rate of the gas, and the gas flow rate. From the above two points, it can be seen that the temperature change not only affects the reduction equilibrium phase of zinc iron oxide, but also dominates the concentration of the reducing agent "carbon monoxide", so it is the most important operating parameter in the present invention. The present inventors carried out reduction experiments using artificially synthesized high-purity zinc iron spinel and carbon monoxide gas streams as reducing agents at different temperatures to derive a phase diagram of the reduction reaction as shown in the figure; the reaction chamber used was An open system 'continues to exchange material and energy with the outside world, and the reaction is in an unbalanced state; the following are detailed according to different temperature ranges: (1) below 5 50 ° C: in the low temperature range, After partial reduction and mixed crystal formation reaction, the iron spinel can be decomposed into three mixed crystals such as iron-containing zinc oxide, zinc-containing ferrous oxide, and low-zinc spinel; because the gas residence time is much shorter than It takes time for Boudouard reaction to reach equilibrium, so the amount of oxidized carbon is sufficient to reduce iron to metal. In addition, because the equilibrium of Boudouard reaction is biased to solid carbon and carbon dioxide at this temperature, the product contains a large range A mixed crystal of ferrous oxide and zinc oxide formed in the 'zinc iron spinel. The birth of iron carbide (2) 5 5 0 ° C to 6 5 0 ° C: Here _ although the trivalent iron can be fully reduced to the divalent part, continue to combine as shown in formula (6), the mechanism is the same as above .

(3) 6 5 0 t: to 9 0 0. (:: With ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, A, A, m, and 度, except for the reduction of gas b and k, the balance of the transport reaction itself is also biased toward the absence of ferrous oxide in the product And some zinc oxides with a metal content of eight to ten are also returned to the ΛΛ metal, which will be carried away by the airflow after evaporation;

1241348

_ Case No. 93105475_ Year V. Description of the invention (9) The production amount of low'iron carbides also increases with temperature Γ >. k decreased significantly. (4) Less than or equal to 9 50 ° C: Here at Gao Yuan ^ The Boudouard reaction is limited in a short period of time ... The oxidation reaction gas is also reduced to the metal state, so the reducing power of zinc hafnium can not be damaged, and Genus. And this temperature has been higher than the boiling point of zinc (903). All of the particles are reduced to blond hair and taken away from the system by the airflow, which strengthens the whole thing. Therefore, the zinc content can be reduced to less than 丨%. No, first Equilibrium. For the reason of carbonization, the reduction treatment used in the present invention is 9 4 5 ~ q. The factory + + condition 1 is the warm production right: the reduction reaction is performed in the carbon gas stream. ^ $ Arc furnace dust removal In addition to zinc and iron oxides, the quality of the fabrics of lead oxide, lead vapor, sodium chloride, and gas γ 丄 / 乂 冋 are shown in (⑽), as shown in the second figure Analysis of melting points by radio-spectroscopy (both lower than 900 t); 夂: the common feature of compound 1 is the fusion of the main compounds in low ash, and two households. Non-equilibrium: "Father and" at this temperature, the airflow ^ a balance will be removed to remove the hair. The Ben Sheming people then combined this one-seater fishing shovel extension, and it used his impurities The special method of the invention: 回收 m meets the original method as the basis of the recycling of the present invention. The object of this patent includes: 1. Using two Wenli treatment, the electric arc furnace The lead and gas contained in the dust are effectively removed to improve the purity of the final product; the solid product in this step is not a mixture of zirconia spar and zinc oxide. After the radon is cooled, it can be collected in the form of meal. Evaporated lead oxide / lead gaseous lead / alkali chloride mixed

1241348 Case No. 93105475 V. Description of the invention (10)

Using carbon monoxide gas as a reducing agent, the evaporated metal zinc is maintained in its metallic state in a reducing carrier gas (carbon monoxide) without being oxidized, and high-purity metal zinc is recovered. ’3. In order to effectively avoid melting of iron, the processing temperature is controlled to 9 4 5 to 9 5 5. (: Sintering iron into recyclable sponge iron. The main feature of the present invention is to provide a method for recovering valence metals contained in dust collection ash of electric arc furnace steelmaking industry. The steps are: (1) Granulation and screening; (2) Pre-treatment before removing impurities: Control the temperature at 9 4 5 ~ 9 5 5 ° c to remove the impurities in the dust collecting ash and impurities of alkali metal chloride, after pre-treatment The obtained sintered particles of a mixture of zinc oxide and zinc-iron spinel are placed in a reaction chamber for the next step; (3) Reduction treatment ·· Using carbon monoxide gas as a reducing agent is introduced into the reaction chamber, and the reduction treatment temperature is 945 ~ 955 t, which can sinter iron into sponge iron without melting and maintain the stability of vaporous metal zinc; (4) Condensation: After the reaction gas flows out of the reaction chamber, it will be condensed quickly, by 945 ~ 95 5 t The equilibrium composition ratio of carbon monoxide to carbon dioxide (99: 1) in the air stream under the temperature conditions can be stored by rapid cooling to avoid reoxidation of zinc caused by excessively high concentration of dioxide; After being rapidly cooled, the metal zinc carried out is condensed into a gold-zinc powder, which can be easily collected by a dust collecting device. [Embodiment] In order to achieve the expected effect and purpose of the present invention, the preferred embodiments will be described in detail. Are as follows: Ding

Page 16 Rev. 1241348 __Case No. 93105475 V. Description of the invention (11) The flow right mainly includes the steps of granulation and sieving, pre-treatment to remove impurities, reduction treatment and condensation ... (I) Granulation and screening : In order to avoid dust emission caused by gas in the processing process, to ensure the health and safety of workers, and to avoid too high soot content in the exhaust gas, which affects product purity, the electric arc furnace dust ash needs to be granulated first. The granulation equipment can be used in this step without special modification; since the dust collecting ash is already rich in gaseous salts, any binding agent needs to be added during the granulation process, and the dust collecting ash has an average particle size. About 1 to 10 V mf Thai body can be directly granulated without grinding; if the granulation disk is used for granulation, its operating conditions are preferably: 1 · The inclination of the granulation disk: the angle between the horizontal and the horizontal is 35 to 40 Degrees; 2. Rotating speed of the granulating disk: 37 ~ 43 rpm; n 1 water / speed · Depending on the size and flow rate of the granulating disk, the moisture content of granulation needs to be controlled at 9 ~ 12%. The size of the granules produced by Ang Ang should be controlled to 5 to 10mm 'in order to take into account both the material and the reactivity at the same time. Therefore, after the granulation step, it must be screened and controlled to go through the details. Coarse particles are guided back to the granulation step. (+) Pre-treatment before removing impurities: In order to ensure the second of the final product after the treatment, it is necessary to remove the chemical compounds and gasified alkali metal salts contained in the dust collection ash before obtaining the ferrous metal. And other impurities; this step is to take advantage of the low melting point of lead and lice alkali metal salts and control the temperature at 945 ~: if it is not, it will be guided by itself,

On the next page, control the reaction atmosphere to oxidizing conditions by putting the material into the dilute stream mode to maintain the high oxidation state with iron. + 1241348 __Case No. 9310547 & _ ± —_ ^ Day Amendment_ V. Description of the invention (12) Miscellaneous strips of wrong compounds and alkali metal chlorides erupted by air flow are in the cooling equipment 4 It is a dust-like mixture, which is collected by dust collection equipment; the solid residue after the pre-treatment is sintered particles of a mixture of zinc oxide and zinc-iron spinel. It has high hardness and high crystallinity, and can directly enter the next treatment. Procedure; XRD crystal phase analysis results are shown in the third figure. Compared with the second figure before processing, it can be clearly seen that the above impurities have been removed. (II) Reduction treatment: This sequence is a reduction step using excess carbon monoxide as a reducing agent; it is at a reaction temperature of 9 4 5 ~ 95 5 ° C, and the oxide and iron spinel are transported to metal respectively. State; because the reaction temperature (9 4 5 ~ 95 5 ° C) is higher than the boiling point of metal ions (903 ° C), zinc evaporates into a gas and is carried out by a stream of carbon monoxide reducing gas. The reducing gas carbon monoxide can preserve the metallic state of zinc. The flow rate of the carbon monoxide gas stream must be controlled. In order to avoid the conversion of carbon monoxide into carbon dioxide and solid carbon at a temperature of 9 4 5 ~ 9 5 5 t, one is caused by excessive carbon dioxide in the gas. The reoxidation of metallic zinc, and the solid carbon deposits generated will affect the composition of the produced brocade iron. The gas residence time is optimal within 1 second. (4) Zinc vapor condensation collection: After the reducing gas rich in zinc vapor flows out of the reaction chamber, a rapid condensation step is performed, which has the following two functions: 1 In the air flow at the temperature of 9 4 5 ~ 9 5 5 ° C The carbon monoxide / carbon dioxide equilibrium composition ratio can be stored by rapid cooling to avoid excessive oxidation of zinc due to excessive carbon dioxide concentration. 2. The metal zinc evaporated and carried by the carbon monoxide gas stream is rapidly condensed to form a metal zinc powder, which can be collected by a dust collecting device. In the processing flow shown in the fourth figure, after the pretreatment and after the condensation step ’, both the ship ’s compounds and the gasification test metal salts are condensed into powder, so

Page 18 1241348

_Case No. 93105475 V. Description of the invention (13) Use of cyclone equipment or bag type dust collection equipment to carry out owing ^ [treatment effect] The mass balance of $ is like the treatment of zinc dust collection ash, according to the method of the present invention, every 10 0 0 kg of dust collection ash feed, as shown in the five diagrams, the use of the process of the present invention in the electric solitary furnace can achieve the following important results: (a) high recovery: According to the process of the present invention, the arc can be reduced to 99 · 9 % Zinc content is metallized and recycled; iron content is \ sponge iron can be directly used as a secondary raw material for the steelmaking industry; after pretreatment :: halide / lead compound powder, the ingredients can be seen , The amount and after 1 sulphur removal * ', the benefit, purification and recovery of lead, chloride parts can be recycled to ^ ^ ^ ^ raw materials' total can at least arc &gt; furnace dust ash more than 9 &% There are strict metal resources. ^ (2) High removal rate: The pre-evaporation treatment step under oxidation conditions can achieve a removal rate of more than 95% for lead compounds and gaseous salts, which greatly improves the purity of the final product. $ μ (II) South purity products • The main products of this process are metal zinc and sponge iron; a. The average purity of metal zinc powder is over 99.5%, containing only a small amount of lead (&lt; 0.4%) And trace zinc oxide (<0.05%), with a metallization ratio of more than 99.9%, can be used directly for anti-rust spraying or entering a refinery to produce high-value and high-purity zinc products, can provide Higher-order uses. b. The average iron content of sponge iron is more than 90%, and the elemental carbon produced by Boudouard reaction accounts for about 4%. Therefore, in addition to metallic iron, it also contains about 10% of iron carbide, and the metallization ratio is about 90%. %, Can be recycled to the steelmaking industry as a secondary raw material.

Page 19, Rev. 1241348, Rev. 93105475 V. Description of the invention (14) (4) Low pollution risk: In this process, the gas and carbon streams are separated, that is, after degassing by pre-calcination, The introduction of a carbon-containing reducing agent greatly reduces the chance of contact between the two. The generated exhaust gas can be post-combusted, effectively reducing the risk of dioxin formation; and the dust collecting ash is subjected to a sterilization step before feeding. Effectively avoid the generation of dust in the main process airflow, ensuring the safety of workers and the quality of exhaust gas. (Five Y means 4 energy sources and improve the quality of valuable metals: The present invention controls the pre-treatment temperature before removing impurities to 945 ~ 9 5 5 ° C, which can not only remove lead compounds and alkali metal chloride salts contained in dust collecting ash first. Impurities such as: can be the purity of the final product after the treatment, and the reaction is still controlled during the reduction treatment ^ 2 at 9j5 ~ 9 5 5 C 'so that zinc oxide and zinc iron spinel are reduced separately \ In this way, the temperature of the pretreatment and reduction reaction is controlled at 9 4 5 ~ 955C, and λ zhangdong is buried. The mandrill is made from an emulsified carbon as the reducing agent. The invention of recovering zinc at a temperature of 0.00% can reduce the amount of fuel energy consumption and reduce the concentration of zinc metal. The ancient economic benefits of electric arc (furnace steelmaking waste lifting VI: the process of the present invention) If the built-in is a reducing agent, instead of using a carbon oxide waste gas generated by a converter, it can save processing costs, and the process exhaust gas can be directly reloaded into the high-performance unit to ensure exhaust products. [Both the effect of raising 1 'cost . Department of households, households, ten, and power4, the present embodiment of the invention has indeed achieved the intended purpose and the same characteristics of the invention patent are disclosed in the ★ 'so the invention can be matched, you may also hit A5 For the monthly requirements, I applied in accordance with the law.

1241348 _Case No. 93105475_Year Month and Day ___ Brief Description of Drawings [Simplified Description of Drawings] The first picture shows the phase diagram of the temperature change of the products of the reduction reaction of zinc-spinel spinel. The second figure shows the X-ray diffraction spectrum analysis of zinc-containing dust collected in the electric arc furnace without the impurity removal treatment. The third figure shows the X-ray diffraction spectrum analysis of the zinc furnace dust containing ash after the pretreatment. The fourth figure shows a basic flowchart of the present invention. The fifth figure shows a mass balance diagram of the processing flow of the present invention. [Annex] 1. It is a phase diagram of the Ci-Iron-Oxygen ternary system at 12,000 K.

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Claims (1)

1241348 The modified method for recovering the valuable gold contained in the dust collection ash of the electric arc furnace steelmaking industry is as follows: (a) granulation and screening; (b) pre-removal treatment: control the temperature at 94 5 ~ 95 5 c The dust compounds contained in the dense dust fire and the impurities of the chlorinated metal salts are removed, and the sintered particles of the zinc oxide and zinc iron spinel mixture obtained after the A treatment are placed in the reaction chamber for the next step; (2) Reduction treatment: Use carbon monoxide gas as a reducing agent to introduce into the reaction chamber. At the same time, the reduction treatment temperature is 9 4 5 ~ 9 5 5 ° C, which can sinter iron into molten iron without melting, and maintain the stability of vapor metal zinc; (IV) Condensation ... After the reaction gas has flowed out of the reaction chamber, it will be rapidly condensed. By the equilibrium composition ratio of carbon monoxide / carbon dioxide in the gas stream at a temperature of 9 4 5 ~ 95 5 ° C (9 9: 1) It is stored after rapid cooling to avoid the reoxidation of zinc caused by excessively high carbon dioxide concentration; and the metal zinc evaporated and carried by the carbon monoxide gas stream is condensed into metal zinc powder after rapid cooling, which is convenient for dust collection equipment. Collection. 2. A method for recovering valence metals contained in dust collection ash of electric arc furnace steelmaking industry as described in item 1 of the scope of patent application, wherein the particle diameter of the product granulated in step 1 is preferably controlled to 5 to 10 mm. 3. A method for recovering valence metals contained in the dust collection ash of the electric arc furnace steelmaking industry as described in item 1 of the scope of the patent application, wherein when the granulation disk is used for granulation, the operating conditions are preferably; Inclination angle: 35 to 40 degrees from horizontal loss angle, granulation disk rotation speed: 37 ~ 43 rpm, and water-threatening amount / rate: depending on the size and flow rate of the granulation disk. ~ Page 22 1241348 Case No. 93105475 Amendment 6. The scope of patent application is 12%. 4. If the valence metal contained in dust collection ash in the scope of patent application is selected, the excessively fine particles will be guided after being crushed. 5. If the valence metal contained in dust collection ash in the scope of patent application is pre-treated, it must be introduced. Under empty parts, zinc and iron are kept stable as impurities of alkali metal salts. 6. If the patent application scope contains the valence metal compounds and alkali chloride metal salt compounds, then pass through the dust collection equipment. 7. If the patent application scope contains the valence metal gas contained in the dust collection ash and is carried by the air stream. This is a method for recovering electric arc furnace steelmaking as described in item 1 of the carbonization, storage of zinc metal, gas stop in the reaction zone, wherein the granulation step must be screened back to the granulation step to continue the granulation Granules and go back to the granulation step. The method for recovering electric steelmaking industry according to item 1, wherein the reaction atmosphere is controlled to be oxidized in the gas flow mode of removing impurities in step two, and only the chemical compound and chlorination according to item 5 are removed by evaporation. A method of the electric arc furnace steelmaking industry, in which the leaded vapor carried by the air stream is condensed into a dust-like mixture in a cooling device and collected. The method for recovering the electric arc furnace steelmaking industry described in item 1, in which the gas stream still contains a large amount of reducing gas monooxygen when the distillate evaporates in step 3, and the flow rate of the carbon monoxide gas stream must be controlled within 1 second. Page 23