JPS62136535A - Method for recovering zinc from iron making dust - Google Patents

Abstract

PURPOSE:To recover zinc from making dust at a high removal rate by subjecting zinc-contg. dust to a leaching treatment in a hydrochloric acid soln. to classify the dust to a zinc rich phase and zinc lean phase and extracting and separating zinc from the zinc rich phase. CONSTITUTION:The zinc-contg. iron making dust is stirred for a specified period at <=0.5pH in the hydrochloric acid soln. and is classified to the zinc rich phase in which the zinc is segregated and (<100mu) and the zinc lean phase (>100mu) in which the zinc concn. is low by a classifier. The zinc rich phase is added to a hydrochloric acid of about 10-30% concn. to a mixing ratio of about 1 (solid): 9-19 (liquid) and is extracted for about one hour at about 40 deg.C temp. A solid-liquid sepn. is executed after the extraction. The separated zinc-contg. aq. soln. is neutralized to about 8.5-10.5pH and the zinc is recovered in the form of precipitate. The solid content separated from the zinc-contg. aq. soln. and the zinc lean phase are subjected to a neutralizing treatment and are reused as an iron source. The zinc is thereby efficiently recovered from the iron making dust and the residue after the zinc extraction is made usable as a iron source for a blast furnace.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for recovering zinc from iron-making dust, and more specifically, the present invention relates to a method for recovering zinc from iron-making dust. This invention relates to a method for recovering high concentrations of zinc from steel dust in the form of

[Prior art] Blast furnace dust contains T, Fe50-40wL% and zinc 1
~4u+L% and other ships, etc., so if the dust is reused as an iron source for a blast furnace, the dust will remain on the inner wall of the furnace and the gas will not be ventilated because the dust contains zinc. In addition, the raw material charged from the top of the furnace falls unevenly, causing a zinc attack problem that further deteriorates the furnace wall, so as a countermeasure, it is necessary to separate and remove zinc from the dust in advance. There is.

Generally, the following method is known as a method for separating zinc from zinc-containing by-products.

(1) Wet cyclone method This method is a beneficiation method that is used only when the particle size distribution of solid particles in water is suitable for separation, and cannot be applied to any type of zinc-containing by-product. .

(2) Method using a rotary kiln This method uses a rotary kiln to reduce zinc compounds and volatilize zinc, but this method requires a large amount of heat energy and is uneconomical, and is not recoverable. The purity of zinc is about 50%, which limits its use.

(3) Chloride roasting method This method is widely applicable to various byproducts, but the processing cost is high.

(4) Extraction method with acid or alkali This method involves treating zinc-containing by-products with an aqueous sulfuric acid solution and an aqueous caustic soda solution, but the running cost is high;
Furthermore, when the residue after zinc removal is reused as blast furnace raw material, it is difficult to remove the residual acid residue, and if iron coexists with the by-product, some of the iron will dissolve. This makes it difficult to separate iron and zinc.

[Problems to be Solved by the Invention 1] As explained above, the present invention was made in view of the problems in various conventional methods for extracting zinc from zinc-containing by-products, and the present invention As a result of intensive research conducted by researchers, it has become possible to efficiently separate iron and zinc from zinc-containing by-products, especially iron-making dust, recover zinc with high purity, and immediately recover the separated iron. They developed a method for recovering zinc from steelmaking dust that can be reused in blast furnaces and is inexpensive to process.

[Means for Solving the Problems 1] The method for recovering zinc from ironmaking dust according to the present invention is characterized by leaching zinc-containing dust with a hydrochloric acid solution and then forming a zinc-concentrated phase and a zinc-dilute phase. Classified into
Next, zinc is extracted from the zinc concentrated phase and subjected to solid-liquid separation, and the separated solid content and the zinc diluted phase are both neutralized and used as an iron source.Meanwhile, the zinc-containing aqueous solution is neutralized to produce zinc. The purpose is to collect the precipitate after dehydration treatment.

The method for recovering zinc from ironmaking dust according to the present invention will be described in detail below.

That is, to specifically explain the method for recovering zinc from ironmaking dust according to the present invention, ironmaking dust as zinc-containing dust is mixed with a hydrochloric acid solution under conditions where the hydrogen ion concentration is 0.5 or less and leaching treatment is performed. , separated into a zinc concentrated phase (<100μ) in which zinc is segregated and a zinc dilute phase (>100μ) with a low zinc concentration by classification using a 100μ classification rock.
In particular, the zinc-enriched phase (<100
μ) with pH > 0.5 and slurry concentration 5-10%
Zinc was extracted under the following conditions, and after solid-liquid separation, the zinc-containing aqueous solution was neutralized in the pH range of 8.5 to 10.5, and the zinc was turned into a precipitate, which was then recovered after dehydration. The dilute phase (>100) and the iron-containing solid content (>100) after zinc recovery are effectively used as an iron source after acid neutralization and washing.

Next, a method for recovering zinc from ironmaking dust according to the present invention will be explained with reference to FIG.

Steel dust, for example, contains T, Fe 30-40wt%, ZnO1-4u+t%,
Mn00.5-1.5wt%, 5iO21-3u+t%
, CaO2-4u+t%, C2O-30u+t%, A1
□ Use one with a chemical composition of 032~3u+L% and moisture 20~25iut%.

In Fig. 1, zinc-containing steelmaking dust 1 is placed in a stirring tank 4, and hydrochloric acid 2 and H2O3 with a concentration of 10 to 30% are added to it. ) Control the amount of charge mixture. ), the solid-liquid mixing ratio is set in the range of 1 (solid):9 to 19 (liquid), and the mixture is stirred for a certain period of time under the condition of PH≦0.5. Next, dust particles (<100μ) 6 and (>100μ) are classified by classification W15.
) and 7, and the (<100 μ) dust particles 6 are sent to an extraction tank 8 and treated with hydrochloric acid at a concentration of 10-30%, 1 (solid): 9-
Extraction was performed at a mixing ratio of 19 (liquid), an extraction salinity of 40°C, and an extraction time of 1 hour.

After that, the zinc extraction dust is centrifuged [9] to perform solid-liquid separation, and the separated zinc-containing aqueous solution 10 is transferred to a reaction tank 12.
In the step, neutralizing agent 13 and flocculant 14 are added to adjust the pH.
Stir and neutralize within the range of 8.5 to 10.5. Subsequently, after being sorted into a supernatant liquid 16 and a zinc precipitate 17 in a retention tank 15, the zinc precipitate 17 is recovered as a zinc concentrated solid material 20 in a dehydrator 18, and stored in a zinc cake hopper 21 to be used as needed. Use as a source of zinc as required. In this case, the results of the zinc extraction experiment from zinc-containing dust 1 are as shown in Figure 2, with a zinc removal rate of approximately 90% (residual Zn concentration < 0.15u).
+t%).

On the other hand, the supernatant liquid 16 separated from the retention tank 15''C and the waste liquid 19 generated from the dehydration 8! However, within the scope of compliance with environmental standards, so-called
The wastewater 24 is neutralized to about PI3, and the entire amount of the wastewater 24 is reused as a water source for the neutralization cleaning tank 25.

On the other hand, the residue 11 separated into solid and liquid by centrifugation fi9 and the low zinc-containing dust (>100μ) classified by classifier 15
(approximately 10% of the total ratio) 7 have hydrochloric acid solution attached to them, so they are transported to the neutralization cleaning tank 25 by a belt conveyor, and the neutralizing agent 26 (slag leaching high pH water and slaked lime or caustic soda, etc.) and pH Add the adjusted wastewater 24 as appropriate,
After stirring, neutralize the mixture to about PI3, which is within the range that meets environmental standards. After that, the slurry 28 after the neutralization treatment and the overflow waste water 27 from the tank are completely centrifuged 8!
29 for solid-liquid separation. As shown in Table 1, the solid content is approximately 30u+t% of T and Fe, and is transferred and stored in the product bin 30 by a belt conveyor and reused as an iron source as appropriate. Further, the waste liquid 32 separated into solid and liquid by the centrifugal separation rock 29 is drained to a predetermined location.

Pile 1 boat (wt%) [Effects of the invention] As explained above, since the method for recovering zinc from ironmaking dust according to the present invention has the above configuration, the removal rate of zinc from ironmaking dust is high and The recovered zinc can be used effectively, the residue after zinc extraction can be reused in its entirety as a source of blast furnace iron, and the recovery process has the excellent effect of being extremely efficient. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the method of recovering zinc from iron-making dust according to the present invention, and FIG. 2 is a diagram showing the extraction rate of zinc in the method of recovering zinc from iron-making dust according to the present invention.

Claims (1)

[Claims] After leaching the zinc-containing dust with a hydrochloric acid solution, it is classified into a zinc-concentrated phase and a zinc-dilute phase, and then zinc is extracted from the zinc-concentrated phase and subjected to solid-liquid separation, and the solid content and zinc-dilute phase are separated. A method for recovering zinc from iron-making dust, characterized in that both are neutralized and used as iron sources, while the zinc-containing aqueous solution is neutralized to form zinc as a precipitate and then recovered after dehydration.