CN108793378B

CN108793378B - Method for removing thallium from thallium-containing tailing pond wastewater

Info

Publication number: CN108793378B
Application number: CN201810625108.8A
Authority: CN
Inventors: 张小云; 易伟灿; 田学达; 方亚东; 武用; 杨媚
Original assignee: Xiangtan University
Current assignee: Xiangtan University
Priority date: 2018-06-17
Filing date: 2018-06-17
Publication date: 2021-05-28
Anticipated expiration: 2038-06-17
Also published as: CN108793378A

Abstract

The invention discloses a method for removing thallium from thallium-containing tailing pond wastewater. According to the method, firstly, ferrous sulfate is added into the waste water of the tailing pond, the dosage of the ferrous sulfate is 10-150 mg/L, the ferrous sulfate is uniformly mixed and reacts for more than 1min, then, reduced iron powder is added, the dosage of the reduced iron powder is 1-10 mg/L, the mixture is uniformly mixed and reacts for more than 5min, liquid-solid separation is carried out after the reaction is finished, and the liquid is the effluent after thallium removal. The invention utilizes ferrous sulfate to remove Tl in the wastewater³⁺Reduction to Tl⁺While being Fe²⁺Is oxidized into Fe under the action of oxygen in the waste water³⁺Fe (OH) with stronger adsorption capacity to thallium and other heavy metal ions is formed in neutral or alkalescent wastewater₃The thallium in the wastewater can be removed; using reduced iron powder as reducing agent to make Tl in waste water⁺The thallium is reduced into solid sponge thallium, so that the thallium in the wastewater can be effectively removed; the process of thallium removal from the wastewater is simple, the effect is stable, and the method has practical application value.

Description

Method for removing thallium from thallium-containing tailing pond wastewater

Technical Field

The invention relates to a method for removing thallium from thallium-containing tailing pond wastewater, and belongs to the technical field of environmental engineering.

Background

Thallium is a heavy metal with extremely strong hazard and can cause damage to the nervous system and central system of the body after entering the human body. Thallium has higher toxicity to mammals than Cd, Cu, Zn, Hg, etc., and is second only to methylmercury. Thallium and its compounds have mutagenicity, carcinogenicity and teratogenicity, and can cause esophageal cancer, liver cancer, carcinoma of large intestine, etc., which greatly threatens human health. In view of the severe toxicity of thallium, the American environmental protection agency regulates the maximum content of thallium in industrial discharge water to be 0.14 mg/L and the maximum residual quantity of thallium in domestic drinking water to be 2 mug/L; the allowable content of thallium specified in the sanitary standard of domestic drinking water in China is 0.1 mug/L, and the limit value of thallium pollutant emission in thallium-related industrial sewage specified in the thallium-related industrial wastewater emission control standard in China is 0.005 mg/L.

Thallium enters a water environment mainly through the development and utilization of thallium-containing mines, dust sedimentation in ore smelting, waste discharge of sulfur mineral areas, waste discharge of printing and dyeing industries and other approaches, and the Tl content in the water body around the thallium-containing mineral areas is high. Tl is commonly used as thallium in water⁺And Tl³⁺Two valence states exist, in natural water and seawater, Tl is generally used as Tl⁺In organic water such as lakes, Tl is generally used as Tl³⁺The morphology exists.

At present, the pollution treatment technology of thallium in water mainly comprises treatment methods such as a chemical precipitation method, a solution extraction method, an ion exchange method, an adsorption method and the like.

The chemical precipitation method is mainly characterized in that S is added into wastewater containing thallium^2-Thallium is removed from the water body in the form of precipitate, jarosite, prussian blue and the like, but the treatment results thereof often fail to meet thallium control standards and secondary pollution is likely to occur.

Although the ion exchange method is recommended by the U.S. environmental protection agency as one of the treatment methods of thallium-polluted water bodies, the ion exchange method is usually very susceptible to the influence of other coexisting alkaline earth metals in thallium-containing water bodies, has low thallium selectivity and has the disadvantage of frequent regeneration.

The solution extraction method is only suitable for removing thallium in a specific solution and is difficult to be applied to the purification of a water body polluted by conventional thallium.

The adsorption method has the advantages of large adsorption capacity, strong selectivity, easy regeneration of the adsorbent and the like, and is a thallium polluted water body treatment technology with a better application prospect. The common adsorbing materials comprise activated carbon, nano metal oxides, biological materials, composite materials and the like. By adopting the activated carbon filter column to treat the thallium-containing wastewater, the thallium in the low-concentration wastewater can be reduced to be below 0.1 mu g/L, but the defects of frequent regeneration, high running cost and the like exist; the metal oxide has good thallium adsorption effect, but has large fluid resistance and difficult solid-liquid separation, and is difficult to popularize and apply.

The method is characterized in that more thallium-containing mineral resources exist in places such as Guangdong and Hunan in China, the thallium content in tailings of Guangdong Yunnan float pyrite is about 50g/t, the thallium content in lead-zinc ore is about 10g/t, and the thallium content in lead-zinc ore raw ore of Baoshan non-ferrous metal ore in Hunan is 5-15 g/t. One part of thallium in mineral resources is transferred to a smelting enterprise along with a concentrate product, so that wastewater and waste gas of the smelting enterprise contain thallium, the other part of thallium enters a tailing pond along with mineral tailings, and after a series of complex reactions such as leaching, dissolving and oxidation reduction and the like, one part of thallium is transferred from a solid phase to a liquid phase in a tailing pond water body, so that the wastewater of the tailing pond contains thallium.

In the existing tailing pond wastewater treatment process in China, the treatment indexes mainly considered are COD, ammonia nitrogen, lead, zinc, copper, arsenic and other heavy metals, and thallium removal is not particularly considered in the original process design and wastewater treatment operation process. In recent years, thallium pollution of water bodies has been paid more and more attention to thallium emission in water bodies and atmosphere due to the occurrence of a plurality of thallium pollution events, and thallium removal treatment is required when the thallium content in the waste water of tailing ponds exceeds the national specified emission standard. Therefore, the thallium removal process for the wastewater of the thallium-containing tailing pond is developed, thallium in the wastewater is effectively removed, and the positive practical significance is achieved for protecting the environment and controlling thallium pollution events.

Disclosure of Invention

The invention aims to provide a method for removing thallium from thallium-containing tailing pond wastewater.

The purpose of the invention is realized by the following steps:

a method for removing thallium from thallium-containing tailing pond wastewater is characterized by comprising the following steps: adding ferrous sulfate into the tailing pond wastewater with the dosage of 10-150 mg/L, namely, calculated by anhydrous ferrous sulfate, adding 10-150 mg of ferrous sulfate into 1L of wastewater, uniformly mixing and reacting for more than 1min, adding reduced iron powder with the dosage of 1-15 mg/L, namely adding 1-15 mg of reduced iron powder into 1L of wastewater, uniformly mixing and reacting for more than 5min, and performing liquid-solid separation after the reaction is finished, wherein the liquid is the effluent after thallium removal, and the solid is the solid waste containing thallium.

Further, the ferrous sulfate is an industrial grade product or a chemical grade product.

Furthermore, the dosage of the ferrous sulfate is preferably 25-100 mg/L.

Furthermore, the reduced iron powder is preferably reduced iron powder with the iron content of more than 90% and the fineness of less than 0.1 mm.

Furthermore, the dosage of the reduced iron powder is preferably 5-10 mg/L.

And the thallium-containing solid waste enters a subsequent treatment and disposal process.

The invention has the following beneficial effects: 1. the Tl existing in the wastewater is treated by ferrous sulfate³⁺Reduction to Tl⁺While being Fe²⁺Is oxidized into Fe under the action of oxygen in the waste water³⁺Fe (OH) with stronger adsorption capacity to thallium and other heavy metal ions is formed in neutral or alkalescent wastewater₃The thallium in the wastewater can be removed; 2. using reduced iron powder as reducing agent to make Tl in waste water⁺The thallium is reduced into solid sponge thallium, so that the thallium in the wastewater can be effectively removed; 3. the method has the advantages of simple process, easy operation, stable effect and low cost in the wastewater thallium removal process, is easy to combine with the existing tailing pond wastewater treatment process, has good effect of removing low-concentration thallium in the wastewater of the thallium-containing tailing pond, and has practical application value.

Detailed Description

The present invention is further described below with reference to examples, but is not limited thereto.

Wastewater sampling is carried out in a tailings pond wastewater treatment station of the non-ferrous metal mining finite liability company in Hunan Baoshan, and water inlet samples and water outlet samples of the wastewater treatment station are respectively taken, wherein the basic properties of the water samples are shown in Table 1.

TABLE 1 basic properties of tailings pond wastewater sample

As can be seen from Table 1, the wastewater mainly contains Pb, Zn, Cd, Cu, Tl and other pollution elements, the content of Tl in the effluent is less than or equal to 0.005 mg/L according to the relevant requirements of the emission Standard of pollutants for the lead and Zinc industry (GB 25466-2010), and the contents of Tl in the water inlet sample and the water outlet sample of the wastewater treatment station of the tailings pond exceed the standard.

Taking 10L of an inlet water sample in each experiment, adding ferrous sulfate, stirring for reacting for 2min, adding reduced iron powder, stirring for reacting for 10min, and performing liquid-solid separation to obtain the effluent after thallium removal. The results of thallium removal from wastewater under different amounts of ferrous sulfate and reduced iron powder are shown in Table 2.

TABLE 2 thallium removal from wastewater test results

As can be seen from Table 2, when the dosage of ferrous sulfate is 25mg/L and the dosage of reduced iron powder is 5mg/L, the Tl content in the effluent of treated water can reach 0.005 mg/L; when the dosage of the ferrous sulfate is 50mg/L and the dosage of the reduced iron powder is 10mg/L, the Tl content in the effluent is basically stabilized at 0.001 mg/L.

Claims

1. A method for removing thallium from thallium-containing tailing pond wastewater is characterized by comprising the following steps: adding ferrous sulfate into the tailing pond wastewater, uniformly mixing and reacting for more than 1min, adding reduced iron powder, uniformly mixing and reacting for more than 5min, and performing liquid-solid separation after the reaction is finished, wherein the liquid is the effluent after thallium is removed, and the solid is thallium-containing solid waste; the dosage of the ferrous sulfate is 25-150 mg/L, and the dosage of the reduced iron powder is 5-15 mg/L.

2. The method for removing thallium from the thallium-containing tailing pond wastewater according to claim 1, characterized in that: the ferrous sulfate is an industrial grade product or a chemical grade product.