CN1373094A

CN1373094A - Process for recovering chrome yellow from chrome containing sewage

Info

Publication number: CN1373094A
Application number: CN 02115678
Authority: CN
Inventors: 钟康年; 刘羽; 罗惠华
Original assignee: Wuhan Chemistry College
Current assignee: Wuhan Chemistry College
Priority date: 2002-04-03
Filing date: 2002-04-03
Publication date: 2002-10-09
Anticipated expiration: 2022-04-03
Also published as: CN1166572C

Abstract

A process for recovering chrome yellow from the Cr-containing waste water and removing metallic ions includes adding the solution containing Pb (2+) ions to said waste water to generate PbCrO4 precipitate and reduce the Cr (6+) concentration to lower than 0.5 mg/L, solid-liquid separation, drying the solid, cooling, pulverizing to obtain chrome yellow powder, adding francolite to the liquid to adsorb Cr (6+) and Pb (2+) ions, solid-liquid separation, and draining the liquid.

Description

Treatment method for recovering chrome yellow from chromium-containing wastewater

Technical Field

The invention relates to a method for comprehensively treating chromium-containing wastewater, recovering chrome yellow from the chromium-containing wastewater and removing metal ions in water, belonging to the technical field of environmental protection engineering.

Background

Cr-containing materials with different concentrations are discharged in parallel in the production process of some industries such as pigment preparation, electroplating and machining⁶⁺The waste water is a resource which is scarce in China and is an important raw material in industry, so that the comprehensive recovery of metals such as chromium in the waste water is beneficial to water purification and has important economic value. In the prior art, various methods for recovering chromium from chromium-containing wastewater to produce chrome yellow exist, but the wastewater treated by the methods often has more lead ions, which causes secondary pollution to water. At present, a treatment method using a reducing agent of ferrous sulfate is generally used, and the method is to treat Cr under a strong acid condition⁶⁺Reduction to Cr³⁺Then Cr is reacted under strongly alkaline conditions³⁺Formation of a hydroxide precipitate, this precipitate and the consequent formation of Fe (OH)₃The precipitate is flocculent, is extremely difficult to filter and has higher separation cost, and in addition, Cr is contained in an acid medium³⁺Can be dissolved out again, and Cr is easily generated⁶⁺The compound (2) causes secondary pollution.

Disclosure of Invention

The invention aims to solve the problems of the prior art and provides a treatment method for recovering chrome yellow from chrome-containing wastewater and effectively avoiding secondary pollution.

The technical scheme adopted by the invention to solve the problems is as follows: for different concentrations of Cr⁶⁺Adding a proper amount of Pb into the wastewater at a temperature of 15-85 ℃ and a pH of 1.2-8.5²⁺The solution of (2) is acted for a general time to make Cr⁶⁺With Pb²⁺Generation of PbCrO₄(chrome yellow) saturated precipitation and Cr in wastewater⁶⁺The concentration of (A) is reduced to below 0.5 mg/l; then the PbCrO precipitated in the wastewater is treated₄Carrying out solid-liquid separation, heating, baking, cooling and crushing the separated solid to obtain chrome yellow powder; then separated Pb-containing²⁺Adding a certain amount of activated carbon fluorine phosphorus ash into the surplus waste waterStone, under the conditions of pH 4.5-7.5 and normal temperature,acting for 1 to several hours, adsorbing Cr⁶⁺And Pb²⁺Separating the plasma metal ion fluorocarbon apatite from the waste water to make the Cr in the waste water⁶⁺、Pb²⁺The concentration reaches and is lower than the comprehensive emission standard and can be directly discharged.

According to the scheme, the alloy contains Cr⁶⁺The concentration of the wastewater is 5.0mg/l to 750.0mg/l, and Pb is contained in the wastewater²⁺The ratio of the lead content of the solution to the chromium content of the wastewater is 4-5: 1, namely 1 g of chromium content is matched with 4-5 g of lead content, and Pb is added²⁺The acting time of the solution is 5-60 minutes (min); in the presence of Pb²⁺The amount ratio of the activated carbon fluorapatite added into the surplus waste water is 1.0-20.0 kg/t, the action time is usually 1-4 hours, and the performance and the technology of the activated carbon fluorapatite for removing toxic metal ions such as lead in the aqueous solution are disclosed in Chinese patent ZL 97109130.7.

The invention has the positive effect that the Cr-containing alloy can be applied to Cr-containing alloy with different concentrations⁶⁺The treatment of waste water, reclaim the chromium resource that our country is short of, make waste water containing hexavalent chromium ion react with excessive lead ion solution and produce the lead chromate of indissolvable salt to make chrome yellow pigment, its basic principle of combination is:

according to the different properties and treatment conditions of the waste water, a plurality of products such as lemon chrome yellow, light chrome yellow, medium chrome yellow, deep chrome yellow, orange chrome yellow and the like can be obtained and used as raw materials of oily and synthetic resin coatings, the resources of chromium and lead are comprehensively recovered, and the recovery rate can reach more than 90 percent; meanwhile, the cheap mineral environment material of the fluorocarbon apatite is used for treating the wastewater for recovering chrome yellow, so that lead ions in the wastewater are removed, the lead ions and the chromium ions in the wastewater are reduced to the industrial discharge standard, and the secondary pollution to water in the process of recovering chromium in the wastewater is effectively avoided; the invention also has the characteristics of simple and convenient treatment process, high recovery rate, low treatment cost and convenient industrial scale use and popularization.

Drawings

FIG. 1 is a block flow diagram of the processing method of the present invention.

Detailed Description

Embodiments of the invention are further described and illustrated below.

Example 1: the chromium-containing wastewater is prepared from potassium dichromate, the concentration of chromium is 700.0mg/l, the pH value is 4.30, 145ml of wastewater with the lead ion concentration of 20.72g/l is added into 1000ml of wastewater, the pH value is 1.26, the mixture is stirred for 10 minutes under the conditions of the pH value of 1.48 and the temperature of 40 ℃, precipitates are separated from water, 4.298g of chrome yellow precipitates are obtained, the concentration of chromium in the wastewater is 0.68mg/l, the concentration of lead is 145.98mg/l, the recovery rate of chromium is 99.89%, and the recovery rate of lead is 94.44%; adding activated carbon fluorapatite into the wastewater from which chrome yellow is separated according to the proportion of 17.46kg/t, stirring for 2 hours at normal temperature under the condition that the pH value is 5.7, filtering, wherein the concentrations of lead ions and chromium ions in the filtrate are 0.51mg/l and 0.01mg/l respectively, and the waste completely reaches the national discharge standard of GB 8978-1996.

Example 2: chromium electroplating wastewater with chromium concentration of 37.0mg/l is added into 800ml of chromium-containing wastewater, 6.5ml of lead-containing solution wastewater with lead ion concentration of 27.72g/l is added, the pH value is 3.5, the mixture is stirred for 10 minutes at the temperature of 40 ℃, 0.1755g of precipitate is obtained, the content of chrome yellow in the precipitate is 88.15 percent, the concentration of chromium in the wastewater is reduced to 2.4mg/l, and the recovery rate of chromium is 93.53 percent; the concentration of lead is 2.45mg/l, and the lead recovery rate is nearly 98.53 percent; adding activated carbon fluorapatite into the wastewater from which chrome yellow is separated according to the proportion of 6.2kg/t, stirring for 2 hours at room temperature under the condition that the pH value is 5.7, filtering, wherein the concentrations of lead ions and chromium ions in the filtrate are 0.75mg/l and 0.21mg/l respectively, and the treated wastewater completely reaches the discharge standard.

Example 3: the chromium-containing wastewater is prepared from potassium dichromate, the concentration of chromium is 100.0mg/l, the PH is 5.42, 19.5ml of wastewater with the lead ion concentration of 27.72g/l and the PH is 21.26 are added into 1000ml of wastewater, and then the wastewater is stirred for 10 minutes under the conditions of the pH being 2.7 and the temperature being 40 ℃ to obtain 0.615g of chrome yellow precipitate, the concentration of chromium in the wastewater is 1.17mg/l, the concentration of lead is 7.19mg/l, the chromium recovery rate is 98.81 percent, and the lead recovery rate is 98.19 percent; activated carbon fluorapatite (19.6 kg of activated carbon fluorapatite in 1t of wastewater) was added to the wastewater from which chrome yellow was separated at a ratio of 19.6kg/t, and the mixture was stirred and mixed at room temperature at a pH of 5.4 for 2 hours, followed by filtration to measure the concentrations of lead and chromium ions in thefiltrate as 0.81mg/l and 0.01mg/l, respectively.

Claims

1. A treatment method for recovering chrome yellow from chrome-containing wastewater is characterized in that Cr-containing wastewater with different concentrations is treated⁶⁺Under the conditions that the temperature is 15-85 ℃ and the PH is 1.2-8.5, adding a proper amount of pb into the wastewater²⁺The solution of (2) is acted for a general time to make Cr⁶⁺With Pb²⁺Production of PbCrO₄Saturated precipitation and Cr in the wastewater⁶⁺The concentration of (A) is reduced to below 0.5 mg/l; then heating, baking, cooling and crushing the wastewater to obtain chrome yellow powder; then separated to contain pb²⁺Adding a certain amount of activated carbon fluorapatite into the surplus wastewater, and reacting for 1 to several hours under the conditions of pH 4.5-7.5 and normal temperature to adsorb Cr⁶⁺And Pb²⁺Separating the plasma metal ion fluorocarbon apatite from the waste water to make the Cr in the waste water⁶⁺、Pb²⁺The concentration reaches or is lower than the comprehensive discharge standard, and the waste water can be directly discharged.

2. The method of claim 1, wherein the Cr-containing wastewater is treated to recover chrome yellow⁶⁺The concentration of the waste water is 5.0mg/l to 750.0 mg/l.

3. A process for the recovery of chrome yellow from chrome-containing wastewater as claimed in claim 1 or 2, wherein the Pb-containing wastewater is added²⁺The ratio of the lead content of the solution to the chromium content of the wastewater is 4-5: 1, and Pb is added²⁺The time of the solution actionis 5-60 minutes.

4. The method according to claim 1 or 2, wherein the waste water containing chromium contains Pb²⁺Adding into surplus waste waterThe amount ratio of the activated carbon fluorine apatite is 1.0-20.0 kg/t.

5. The process for recovering chrome yellow from chromium-containing wastewater as claimed in claim 1 or 2, wherein the concentration of chromium is 700.0mg/l, pH 4.30, 145ml of wastewater with 20.72g/l lead ion concentration and 1.26 pH are added to 1000ml of wastewater, and the mixture is stirred at 40 ℃ and pH 1.48 for 10 minutes, and the precipitate is separated from water to obtain 4.298g chrome yellow precipitate, the concentration of chromium in the wastewater is 0.68mg/l, the concentration of lead is 145.98mg/l, the recovery rate of chromium is 99.89%, and the recovery rate of lead is 94.44%; activated carbon fluorapatite is added into the wastewater from which chrome yellow is separated according to the proportion of 17.46kg/t, the mixture is stirred for 2 hours under the condition of the pH value of 5.7 and the normal temperature, and then the mixture is filtered, and the concentration of lead ions and the concentration of chromium ions in the filtrate are respectively 0.51mg/l and 0.01 mg/l.

6. The process for recovering chrome yellow from chromium-containing wastewater as claimed in claim 1 or 2, wherein the concentration of chromium is 37.0mg/l, 6.5ml of lead-containing solution wastewater having a lead ion concentration of 27.72g/l is added to 800ml of chromium-containing wastewater, pH is 3.5, and the mixture is stirred at 40 ℃ for 10 minutes to obtain 0.1755g of precipitate, the content of chrome yellow in the precipitate is 88.15%, the concentration of chromium in the wastewater is reduced to 2.4mg/l, and the recovery rate of chromium is 93.53%; the concentration of lead is 2.45mg/l, and the lead recovery rate is nearly 98.53 percent; activated carbon fluorapatite is added into the wastewater from which chrome yellow is separated according to the proportion of 6.2kg/t, the mixture is stirred for 2 hours under the condition that the pH value is 5.7 and the room temperature, and the mixture is filtered, wherein the concentration of lead ions and the concentration of chromium ions in the filtrate are respectively 0.75mg/l and 0.21 mg/l.

7. The process for recovering chrome yellow from chromium-containing wastewater as claimed in claim 1 or 2, wherein the concentration of chromium is 100.0mg/l, pH is 5.42, 19.5ml of wastewater with a lead ion concentration of 27.72g/l and pH is 21.26 are added to 1000ml of wastewater, and then stirred at 40 ℃ for 10 minutes at pH 2.7 to obtain 0.615g of chrome yellow precipitate, the concentration of chromium in the wastewater is 1.17mg/l, the concentration of lead is 7.19mg/l, the chromium recovery rate is 98.81%, and the lead recovery rate is 98.19%; activated carbon fluorapatite was added to the wastewater from which chrome yellow was separated in a proportion of 19.6kg/t, and the mixture was stirred and mixed at room temperature at a pH of 5.4 for 2 hours, followed by filtration to measure the concentrations of lead and chromium ions in the filtrate as 0.81mg/l and 0.01mg/l, respectively.