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Processing method for resource recycling and zero discharge of steel hydrochloric acid pickling waste liquid

A technology of pickling waste liquid and treatment method, which is applied in the direction of metallurgical wastewater treatment, preparation of iron compounds, chemical instruments and methods, etc., can solve the problems of failure to meet national standards, no multiple cycles, low use value, etc., and achieve treatment Low cost, water saving, no secondary pollution effect

Inactive Publication Date: 2016-11-16
TIANJIN ZHENGDA SCI &TECH CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the Chinese Invention Patent Publication No. CN103553146 A, the waste calcium carbide slag is used to process the iron and steel pickling waste liquid to prepare magnetite powder. The pH of the production process is 5.0-6.0. Magnetite powder with iron content, but high energy consumption, the waste water after treatment contains iron, and direct discharge will cause secondary pollution; in the Chinese invention patent publication number CN104529032 A, calcium carbide slag is used to adjust the pH of the hydrochloric acid pickling waste solution to 4.0- 5.0, add 30% hydrogen peroxide to oxidize, iron black reaction occurs at 70-80°C, iron sludge contains only 44%-50% iron, the use value is low, the filtrate after filtration does not have multiple cycles, the water consumption is large, and the obtained low content of chlorine The calcium chloride solution is directly evaporated, and the energy consumption is high, and because of the low pH value of the reaction process in this process, the filtrate may contain high iron ions, and the obtained calcium chloride product cannot meet the national standard

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The pH of the waste hydrochloric acid pickling solution for iron and steel is <0, and the content of iron ions is 12%.

[0029] (1) Neutralize pre-oxidation and adjust pH

[0030] The original iron and steel pickling waste liquid is diluted 1 times by volume, and under the stirring of ventilated air, the prepared calcium carbide slag slurry (15% carbide slag suspension in terms of calcium hydroxide mass fraction) is slowly added to the iron and steel pickling waste. In the solution, adjust the pH at 8.5 and enter the next step of oxidation.

[0031] (2) Air oxidation

[0032] Naturally heat up the suspension obtained in the previous step to 50°C, pass through air for oxidation, and the air velocity is 0.15m 3 / (m 2 ﹒ min), and continuously add the calcium carbide slag slurry used in (1), keep the pH value at 8.5, and form a dark green suspension, nFe 3+ / nFe 2+ Reach 2:1, stop oxidation.

[0033] (3) After stopping the oxidation, use the calcium carbide slag slur...

Embodiment 2

[0036] Iron and steel pickling waste solution pH<0, iron ion content 12%.

[0037] (1) Neutralize pre-oxidation and adjust pH

[0038] Slowly add the prepared calcium carbide slag slurry (15% carbide slag suspension in terms of calcium hydroxide mass fraction) to the steel pickling waste, adjust the pH to 8.5, enter the next step of oxidation, and naturally heat up to 30°C .

[0039] (2) Air oxidation

[0040] Into the 30°C suspension in the previous step, air is introduced at a velocity of 0.15m 3 / (m 2 ﹒ min), and continuously add the calcium carbide slag slurry used in (1), keep the pH 8.0 constant, forming a dark green suspension, nFe 3+ / nFe 2+ Reach 1.2:1, stop oxidation.

[0041] (3) After stopping the oxidation, use the calcium carbide slag slurry in (1) to adjust the pH of the suspension to 9.0, heat the suspension to 90° C. with steam, and stir for 2 hours.

[0042] After the synthesis reaction is completed, it is filtered with a plate and frame filter press,...

Embodiment 3

[0044] The pH value of the waste hydrochloric acid pickling solution for iron and steel is 0-1, and the content of iron ions is 8%.

[0045] (1) Neutralize pre-oxidation and adjust pH

[0046] The filtrate filtered by the plate-and-frame filter press treated as in Example 1 and carbide slag were used to prepare carbide slag suspension (25% carbide slag suspension in terms of calcium hydroxide mass fraction). Under air stirring, the calcium carbide slag slurry is slowly added to the steel pickling waste liquid to react, stir evenly, adjust the pH at 9.0, and enter the next step of oxidation.

[0047] (2) Air oxidation

[0048] Into the 50°C suspension in the previous step, pass air into it for oxidation, and the air velocity is 0.15m 3 / (m 2 ﹒ min), and continuously add the calcium carbide slag slurry used in (1), keep the pH 8.5 constant, forming a dark green suspension, nFe 3+ / nFe 2+ Reach 1.6:1, stop oxidation.

[0049] (3) After stopping the oxidation, heat the susp...

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PUM

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Abstract

The invention discloses a processing method for resource recycling and zero discharge of steel hydrochloric acid pickling waste liquid. The method adopts the process steps of carbide slag neutralization and pre-oxidation, air oxidation, heating synthesis, press filtration, filtrate circulation and concentration, acid gas absorption and the like so as to prepare high-iron-content magnetic iron compounds and liquid calcium chloride. The method disclosed by the invention takes industrial waste, namely carbide slag, as a raw material for processing steel hydrochloric acid pickling waste liquid, controls reasonable process parameters for recycling magnetic iron compounds which can be used for replacing iron ore powder in the iron industry, have the iron content of 52-62% and meet the iron ore powder standard as well as liquid calcium chloride which meets the 'GBT26520-2011' standard, and realizes the zero discharge of pollution control in steel enterprises. Moreover, the method is simple and stable, strong in operability, little in water consumption and low in energy consumption, greatly reduces the processing cost, and is particularly suitable for processing the steel pickling waste liquid in medium and small-sized enterprises.

Description

technical field [0001] The invention belongs to the field of waste liquid recovery and utilization, and in particular relates to a method of using industrial waste calcium carbide slag to treat steel hydrochloric acid pickling waste liquid, reclaiming magnetic iron compounds and liquid calcium chloride for ironmaking, and realizing resource recovery of steel pickling waste liquid and zero-emission processes. Background technique [0002] Before the surface processing of steel workpieces, it is necessary to use acid to remove the oxides on the surface to meet the surface processing standards. During the pickling process, the acid concentration is high and the dosage is large, so a large amount of pickling waste liquid will be produced. According to statistics, in 2014, my country's steel pickling waste (free acid content 2-3%, iron content 5-20%) discharge was about 65 million tons, and its pH, COD and SS values ​​far exceeded the national sewage discharge level two Standard...

Claims

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Application Information

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IPC IPC(8): C02F9/10B01D53/78C01G49/00
CPCC02F9/00B01D53/78B01D2258/02C01F11/28C01G49/0009C02F1/001C02F1/02C02F1/04C02F1/66C02F1/72C02F1/74C02F2103/16
Inventor 金秀红韩旭沈晓莉王潇张惠欣
Owner TIANJIN ZHENGDA SCI &TECH CO LTD
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