CN111992258A

CN111992258A - Method for treating heavy metal pollution in sulfide ore tailings

Info

Publication number: CN111992258A
Application number: CN202010922047.9A
Authority: CN
Inventors: 王桂芳; 肖慧珍; 朱金良; 杨金林; 马少健; 丁晨辉; 刘娜; 王翼文
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2020-11-27
Anticipated expiration: 2040-09-04
Also published as: CN111992258B

Abstract

The invention discloses a method for treating heavy metal pollution in sulfide ore tailings, which comprises the following steps: mixing calcium bentonite suspension with solid Na₂CO₃Performing sodium treatment to obtain a sodium-treated bentonite suspension, aging, adding a modifier for modification to obtain modified bentonite, drying and grinding to obtain a treatment material; mixing the treatment material with the sulfide ore tailings and the simulated acid rain solution, oscillating at a constant speed, and filtering and leaching the mixture to obtain the treated tailing leachate. The raw material calcium bentonite used in the method is low in price, and the requirement on the environment is low due to the use of few organic modifiers; meanwhile, the method of the invention has simple operation and good curing effect, and is convenient for industrial productionThe preparation is used.

Description

Method for treating heavy metal pollution in sulfide ore tailings

Technical Field

The invention belongs to the field of tailing treatment, and particularly relates to a method for treating heavy metal pollution in sulfide tailing.

Background

Most of metal mines in China are primary sulfide deposits, and a large amount of sulfide tailings are left after mining and mineral dressing. The sulfide minerals react with moisture and oxygen in the air under natural environment to generate sulfuric acid through acidification, and the sulfide mine tailings form acidic mine wastewater under the leaching action of rainwater, so that heavy metals in the tailings are promoted to be dissolved out. Heavy metals are not easy to degrade in soil, can stably exist for a long time, and have great toxic effect on the environment even at low concentration. Heavy metals can be absorbed and enriched in the plant body through the roots of the plant, so that the growth and development of the plant are influenced, and even the plant withers; and the food can enter human bodies and animal bodies through food chains, and the growth, development and metabolism of the human bodies and the animal bodies are damaged. Disasters and environmental hazards caused by heavy metals worldwide are common: water preferably acquired from organic mercury pollution such as japan and bone softening and bone atrophy from cadmium pollution; the cadmium, lead and arsenic of a certain factory in Sweden exceed the standards, so that the natural abortion rate and the fetal teratogenesis rate of local female workers are obviously increased. The results of sampling and analyzing the soil, water and plants around the Poplar mountain washing tailing pond of the copper mine of the Hill mountain of Anhui cupling, show that the content of heavy metal elements, particularly As and Cu, in the soil around the tailing pond is high, wherein the content of Cu in the cover soil in the pond exceeds the national soil three-level standard by 2 times, and the content of As exceeds the national soil three-level standard by 100 times. The research shows that the soil around the tailing pond is polluted by Cu, Zn, Ni, Pb, Cr and Cd in different degrees, wherein the pollution of Cu and Cd is the most serious and exceeds the national second-level soil standard. Therefore, heavy metals in the sulfide tailings must be treated.

Because heavy gold is in the tailing pondThe ion dissolution is a long-term and slow process, the engineering cost for specially treating the wastewater is high, and heavy metal ions can be continuously dissolved out and continuously pollute the surrounding environment as long as a source tailing pond is not treated. Therefore, the core problem of controlling heavy metal pollution of sulfide ore tailings is source control in the reservoir. The reason for releasing heavy metal ions from sulfide ore tailings is mainly O₂、Fe³⁺And the action of microorganisms, so that some researchers propose several in-library source control methods, such as a neutralization method, a bactericide method, an isolation method, a passivation coating method and the like.

The neutralization method is to fill a tailing pond with alkaline substances such as limestone, lime, caustic soda, industrial fly ash and ferrous oxide together with sulfur-containing tailings to increase the pH value of tailing leachate so as to control the release of heavy metals. The covering method is a method for covering the surface of a mine with materials such as water, sludge, clay, crushed stone, wood and the like to isolate oxygen. Thiobacillus ferrooxidans (A.f bacteria) can promote Fe²⁺Is oxidized into Fe³⁺And is Fe³⁺The oxidation rate for pyrite was 106 times higher than in the case of oxygen. A.f bacteria can accelerate oxidation of pyrite in sulfide ore tailings, and can inhibit A.f bacteria by using bactericide to inhibit activity of microorganism and reduce Fe²⁺Is oxidized into Fe³⁺Thereby slowing the oxidation of the sulphide ore tailings to prevent the production of AMD. There are reports in the literature that tailing passivators are used to inhibit oxidation of tailings, and adsorbing materials such as peanut shells, rice straws and corn stalks are used to remove heavy metals and sulfate ions. However, these methods are difficult to operate, high in economic cost and volatile. Therefore, a method for treating heavy metals in the sulfide ore tailings, which can overcome the above problems, needs to be found.

Disclosure of Invention

In view of the above, the invention aims to provide a method for treating heavy metal pollution in sulfide tailings, which has the advantages of simple process, cheap and easily available raw materials, and greatly reduced heavy metal elution amount in the treated sulfide tailings.

A method for treating heavy metal pollution in sulfide ore tailings comprises the following steps:

(1)preparing calcium bentonite and deionized water into a first turbid liquid with 5-7% of ore pulp concentration, stirring in a constant-temperature water bath at 60-75 ℃ to uniformly disperse, and adding solid Na₂CO₃Continuously stirring for 1-2 h to obtain a second suspension; wherein, solid Na₂CO₃The using amount of the bentonite is 1-5% of the mass of the calcium bentonite;

(2) aging the second suspension for 1-2 h, adding a modifier, stirring for 3-4 h in a constant-temperature water bath at 60-75 ℃, centrifuging for 20-30 min, removing supernatant, washing and separating the obtained precipitate with deionized water, and repeating centrifuging and washing for multiple times to obtain modified bentonite; the modifier is selected from at least one of 1,6 hexamethylene Diamine (DA), Triethylene Tetramine (TTA), tetraethylene pentamine (TEPA) and sodium diethyldithiocarbamate (DDTC), and the dosage of the modifier is 95mmol/100g of calcium bentonite;

(3) drying the modified bentonite at 85-95 ℃, and then grinding and sieving to obtain a sulfide ore tailing treatment material;

(4) mixing the sulfide ore tailings, the treatment material and the simulated acid rain solution at 30-40 ℃, oscillating at a constant speed for 1-72 hours, and filtering and leaching the mixture to obtain a treated tailings leachate, wherein the ratio of the sulfide ore tailings, the treatment material and the simulated acid rain solution is 10 g: 0.5-2 g: 30-50 mL.

In the preferable technical scheme, in the step (1), the concentration of the ore pulp of the first suspension is 6%, and the first suspension is stirred in a constant-temperature water bath at 70 ℃ for 10-20 min, preferably for 15 min.

In the preferable technical scheme, in the step (1), solid Na is added₂CO₃Then stirring is continued for 90 min.

In a preferable technical scheme, in the step (2), the temperature of the thermostatic waterbath is 70 ℃, and the stirring time is 4 hours.

In a preferred embodiment, in step (2), the centrifuging and washing are performed multiple times by: and after supernatant liquid is removed by centrifugal separation, injecting deionized water into the precipitate obtained by separation for diluting to two times, uniformly stirring, performing centrifugal separation again, injecting water for diluting, and repeating for 3-5 times.

In the preferable technical scheme, in the step (3), the drying time is 24-48 h, and 24h is preferable.

In a preferred embodiment, in step (3), the ground and sieved particle size is-200 mesh (less than 200 mesh), i.e., 0.074 μm size fraction.

In the preferred technical scheme, in the step (4), the sulfide tailings, the treatment material and the simulated acid rain solution are mixed at 30 ℃.

In a preferred technical scheme, in the step (4), the constant oscillation speed is 200 rpm.

In the preferred technical scheme, in the step (4), the ratio of the sulfide ore tailings, the treatment material and the simulated acid rain solution is 10 g: 1 g: 40 mL.

The method uses sodium carbonate to perform sodium treatment on the calcium bentonite with weak solidification capability, changes the surface property of the calcium bentonite, expands the interlayer distance of the calcium bentonite, and improves the cation exchange capability of the calcium bentonite; further, the bentonite is organically modified by using a modifier, so that the chemical bond force between the bentonite and heavy metal is increased, and the modified bentonite is obtained; based on the self-adsorption of the bentonite and the complexing effect of the modifier intercalation on heavy metal ions, the heavy metal is solidified under specific conditions, so that the elution amount of the heavy metal in the sulfide tailings is reduced, and the heavy metal pollution treatment in the sulfide tailings is realized. The invention takes two lead-zinc mine tailings in different producing areas and three tin polymetallic mine tailings with different weathering degrees as research objects, researches the heavy metal ion dissolution rules of five sulfide mine tailings before and after treatment, finds that the method has good curing effect on sulfide mine tailings with different acid-producing potentials or different types, can effectively reduce the heavy metal dissolution amount of the sulfide mine tailings, and achieves the environmental protection purpose of treating heavy metal pollution in the sulfide mine tailings.

Compared with the prior art, the invention has the following beneficial technical effects:

the raw material calcium bentonite used in the method is low in price, and the requirement on the environment is low due to the use of few organic modifiers; meanwhile, the method of the invention has simple operation and good curing effect, and is convenient for use in industrial production.

Drawings

FIG. 1A is a comparison of XRD patterns of raw material calcium bentonite (R-Mt, also called Ca-Mt), sodium bentonite (Na-Mt) obtained in step (1) of example 1, and sulfide ore tailing treatment materials (DA-Mt, TTA-Mt, DDTC-Mt and TEPA-Mt) obtained in step (3) of examples 1 to 4.

Fig. 1B is an SEM image of the raw material calcium bentonite.

Fig. 1C is an SEM image of the sulphide ore tailings remediation material obtained in step (3) of example 1.

Fig. 1D is an EDS diagram of the sulphide ore tailings remediation material obtained in step (3) of example 1.

Fig. 2A is a graph of the cumulative elution amount of heavy metal Zn in tailings of a lead-zinc mine tailings (F) after solidification of different sulfide mine tailing treatment materials (DA-Mt, TTA-Mt, and TEPA-Mt) in examples 2 to 4 and different reaction times (2h, 4h, 8h, 24h, 48h, and 72 h).

Fig. 2B is a graph of the cumulative elution amount of heavy metal Mn in tailings of a lead-zinc mine tailings (F) after solidification of different sulfide mine tailing treatment materials (DA-Mt, TTA-Mt, and TEPA-Mt) in examples 2 to 4, with different reaction times (2h, 4h, 8h, 24h, 48h, and 72 h).

FIG. 2C is a graph of the cumulative elution amount of heavy metal As in the tailings after the solidification of a certain lead-zinc tailings (F) by different sulfide tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) in examples 2-4 for different reaction times (2h, 4h, 8h, 24h, 48h and 72 h).

FIG. 2D is a graph of the cumulative elution amount of heavy metal Pb in the tailings of a lead-zinc mine (F) after solidification of the tailings by using different sulfide mine tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) in examples 2 to 4 and by using different reaction times (2h, 4h, 8h, 24h, 48h and 72 h).

Fig. 3A is a graph of the cumulative elution amount of heavy metal Zn after DDTC-Mt in examples 5 to 9 was cured for different times (2h, 4h, 8h, 24h, 48h, 72h) on different sulfide ore tailings (F, YD, CH1, CH2, CH 3).

Fig. 3B is a graph of the cumulative elution amount of heavy metal Mn after DDTC-Mt in examples 5 to 9 was solidified for different times (2h, 4h, 8h, 24h, 48h, 72h) for different sulfide ore tailings (F, YD, CH1, CH2, CH 3).

FIG. 3C is a graph of the cumulative elution amounts of heavy metal As in examples 5 to 9, which are obtained by curing DDTC-Mt for different sulfide ore tailings (F, YD, CH1, CH2 and CH3) for different times (2h, 4h, 8h, 24h, 48h and 72 h).

FIG. 3D is a graph showing the cumulative elution amount of heavy metal Pb after curing of DDTC-Mt in examples 5 to 9 for different sulfide ore tailings (F, YD, CH1, CH2 and CH3) for different times (2h, 4h, 8h, 24h, 48h and 72 h).

Fig. 4A is a graph of the cumulative elution amount of heavy metal Zn after five tailings without added tailing treatment materials in comparative example 1 are eluted for different time periods (2h, 4h, 8h, 24h, 48h and 72 h).

Fig. 4B is a graph of the cumulative elution amount of heavy metal Mn after five tailings without added tailing treatment materials in comparative example 1 are eluted for different time periods (2h, 4h, 8h, 24h, 48h and 72 h).

Fig. 4C is a graph of the cumulative elution amount of heavy metal As after five tailings without added tailing treatment materials in comparative example 1 were eluted for different periods of time (2h, 4h, 8h, 24h, 48h, 72 h).

Fig. 4D is a graph showing the cumulative elution amount of heavy metal Pb after five kinds of tailings without adding the tailing treatment material in comparative example 1 are eluted for different times (2h, 4h, 8h, 24h, 48h and 72 h).

FIG. 5 is a graph showing the cumulative elution amounts of heavy metals Zn, Mn, As and Pb after 4 hours of solidification of five tailings from raw bentonite ore in comparative example 2.

Detailed Description

In order to better explain the present invention and to facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following examples are illustrative only and do not represent or limit the scope of the present invention, which is defined by the claims.

The reagents and instruments used in the following examples are not indicated by manufacturers, and are all conventional products available on the market. For example, inductively coupled plasma mass spectrometers, model: plasma Quant MS from Jena Analytik Jena AG, Germany.

Five tailing samples are respectively collected in three different mining areas, wherein two tailing samples are respectively collected from weathered tailings (YD for short) of a tailing pond of a lead-zinc ore dressing plant in the city of Nemontage Hongfeng and tailings (F for short) weathered for years in the tailing pond of the lead-zinc ore dressing plant in the city of Guangxi Stephania, and the other three tailing samples are collected from three tailings with different weathered degrees in the tailing pond of a tin polymetallic ore dressing plant in the county of Guangxi Nandan and are respectively named as fresh tailings (marked as CH1), weathered tailings (marked as CH2) and tailing sediments (marked as CH 3). The fresh tailings are taken from a mine discharge port of a tailing pond, are dark gray in color and are named as fresh tailings because of short oxidation time; the weathered tailings are surface tailings which are collected from the surface of the tailings pond and weathered for 2-3 years, and the color of the surface tailings is slightly darker than that of fresh tailings; the tailings deposit is the tailings which are collected from a tailings pond and piled for more than ten years, and is gray brown. The tailings YD are white and grey; the tailings F are earthy yellow due to weathering for many years. The five tailing samples belong to sulfide tailings, are all tailings which are taken from 0-25 cm below the surface layer of a tailing pond, are sampled according to a uniform point distribution method, and are naturally air-dried, crushed and uniformly mixed for later use.

The bentonite sample used in the experiment is calcium bentonite (Ca-Mt) in certain producing area of inner Mongolia, and the chemical component is SiO₂And Al₂O₃Mainly comprises 64.37 percent and 16.05 percent of SiO₂、Al₂O₃The content ratio of (A) to (B) is 4.01, Fe₂O₃And CaO in a relatively high amount, with a blue absorption of 43.7g/100g, a cation exchange capacity of 89mmol/100g, and a d (001) value of 1.50 nm.

X-ray diffraction analysis (XRD) an X-ray diffractometer (SMARTLAB3KW) manufactured by Japan K.K., and an oriented piece was formed by a natural sedimentation method to perform structural analysis such as phase composition of a sample. The test conditions were: and a continuous scanning mode is adopted, wherein the scanning range 2 theta is 3-80 DEG, and the scanning speed is 8 DEG (2 theta)/min.

Interpretation of terms:

concentration of ore pulp: the pulp is a mineral slurry. After the minerals are dispersed in the liquid to form a solution, the content of the minerals in the solution is the pulp concentration. The following pulp concentration refers to the bentonite content in a solution of bentonite and water.

Simulated acid rain solution pH 4.5: adding a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 4.8:1 into deionized water, marking the obtained solution as an acid rain stock solution, then adding water to dilute the acid rain stock solution according to acid rain grade division, and preparing the acid rain stock solution into a simulated acid rain solution with the pH value of 4.5.

Example 1

(1) Weighing 40g of calcium bentonite, placing the calcium bentonite in a glass beaker with the capacity of 1L, and adding deionized water to prepare suspension with the pulp concentration of 6% (namely, the mass fraction of the calcium bentonite is 6%); stirring the suspension in water bath, electrically stirring at 70 deg.C for 15min, dispersing the suspension, and adding 2.0g (5 wt% of calcium bentonite) of analytically pure solid Na₂CO₃Continuously stirring for 90min to obtain suspension of sodium bentonite;

(2) aging the suspension of the sodium bentonite for 2 hours, adding a modifier sodium diethyldithiocarbamate (DDTC), stirring for 4 hours in a constant-temperature water bath at 70 ℃, centrifugally separating to remove supernatant, injecting deionized water into the precipitate obtained by separation to dilute the precipitate to two times, uniformly stirring, centrifugally separating again, injecting water to dilute the precipitate for 3-5 times, and washing off the excessive modifier on the surface of the precipitate, wherein the dosage of the modifier is 38 mmol;

(3) and (3) putting the washed modified bentonite sample into an oven, drying for 24 hours at 95 ℃, grinding the sample by using an agate container mortar, and sieving the ground sample by using a 200-mesh sieve to prepare a sulfide ore tailing treatment material, which is marked as DDTC-Mt.

(4) Weighing 10g of certain lead-zinc ore tailings (F) and placing the tailings in an erlenmeyer flask, and adding 1g of DDTC-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 2

(1) Weighing 40g of calcium bentonite, and placing in a containerDeionized water is added into a 1L glass beaker to prepare suspension with 6 percent of ore pulp concentration (namely, 6 percent of the mass fraction of the calcium bentonite); stirring the suspension in water bath, electrically stirring at 70 deg.C for 15min, dispersing the suspension, and adding 2.0g (5 wt% of calcium bentonite) of analytically pure solid Na₂CO₃Continuously stirring for 90min to obtain suspension of sodium bentonite;

(2) aging the suspension of the sodium bentonite for 2 hours, adding a

modifier

1,6 hexamethylene Diamine (DA), stirring for 4 hours in a constant-temperature water bath at 70 ℃, centrifugally separating to remove supernatant, injecting deionized water into the precipitate obtained by separation to dilute the precipitate to two times, uniformly stirring, centrifugally separating again, injecting water to dilute the precipitate for 3-5 times, and washing off the excessive modifier on the surface of the precipitate, wherein the dosage of the modifier is 38 mmol;

(3) and (3) putting the washed modified bentonite sample into an oven, drying for 24 hours at 95 ℃, grinding the sample by using an agate container mortar, and sieving the ground sample by using a 200-mesh sieve to prepare a sulfide ore tailing treatment material which is marked as DA-Mt.

(4) Weighing 10g of certain lead-zinc ore tailings (F) and placing the tailings in an erlenmeyer flask, and adding 1g of DA-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 3

(2) aging the suspension of the sodium bentonite for 2 hours, adding a modifier triethylenetetramine (TTA), stirring for 4 hours in a constant-temperature water bath at 70 ℃, centrifugally separating to remove supernatant, injecting deionized water into the precipitate obtained by separation to dilute the precipitate to two times, uniformly stirring, centrifugally separating again, injecting water to dilute the precipitate for 3-5 times, and washing off the excessive modifier on the surface of the precipitate, wherein the dosage of the modifier is 38 mmol;

(3) and (3) putting the washed modified bentonite sample into an oven, drying for 24 hours at 95 ℃, grinding the sample by using an agate container mortar, and sieving the ground sample by using a 200-mesh sieve to prepare a sulfide ore tailing treatment material which is marked as TTA-Mt.

(4) Weighing 10g of certain lead-zinc ore tailings (F) and placing the tailings in an erlenmeyer flask, and adding 1g of TTA-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 4

(2) aging the suspension of the sodium bentonite for 2 hours, adding a modifier Tetraethylenepentamine (TEPA), stirring for 4 hours in a constant-temperature water bath at 70 ℃, centrifugally separating to remove supernatant, injecting deionized water into the precipitate obtained by separation to dilute the precipitate to two times, uniformly stirring, centrifugally separating again, injecting water for diluting, repeating for 3-5 times, and washing off the excessive modifier on the surface of the precipitate, wherein the dosage of the modifier is 38 mmol;

(3) and (3) putting the washed modified bentonite sample into an oven, drying for 24 hours at 95 ℃, grinding the sample by using an agate container mortar, and sieving the ground sample by using a 200-mesh sieve to prepare a sulfide ore tailing treatment material, which is marked as TEPA-Mt.

(4) 10g of certain lead-zinc ore tailings (F) are weighed and placed in a conical flask, and 1g of TEPA-Mt and 40ml of simulated acid rain solution with the pH value of 4.5 are added, and the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 5

(4) Weighing 10g of certain lead-zinc ore tailings (F) and placing the tailings in an erlenmeyer flask, and adding 1g of DDTC-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 6

(4) Weighing 10g of certain lead-zinc ore tailings (YD) and placing the tailings into a conical flask, and adding 1g of DDTC-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 7

(1) Weighing 40g of calcium bentonite, placing the weighed calcium bentonite into a glass beaker with the capacity of 1L, and adding deionized water to prepareSuspension with the concentration of the ore forming slurry being 6 percent (namely, the mass fraction of the calcium bentonite is 6 percent); stirring the suspension in water bath, electrically stirring at 70 deg.C for 15min, dispersing the suspension, and adding 2.0g (5 wt% of calcium bentonite) of analytically pure solid Na₂CO₃Continuously stirring for 90min to obtain suspension of sodium bentonite;

(4) Weighing 10g of fresh tailings (CH1) of a tin polymetallic ore into a conical flask, and adding 1g of DDTC-Mt and 40ml of simulated acid rain solution with the pH value of 4.5, wherein the reaction temperature is 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 8

(4) 10g of weathered tailings (CH2) of a tin polymetallic ore were weighed into a conical flask, and 1g of DDTC-Mt and 40ml of a simulated acid rain solution with pH 4.5 were added at a reaction temperature of 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Example 9

(4) 10g of a tin multimetal ore tailing deposit (CH3) was weighed into a conical flask and 1g of DDTC-Mt and 40ml of a simulated acid rain solution having a pH of 4.5 were added at a reaction temperature of 30 ℃. After shaking for 2h, 4h, 8h, 24h, 48h and 72h respectively at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Comparative example 1

Weighing 10.0g of certain lead-zinc ore tailings (F) and placing the tailings into a conical flask, adding 40mL of simulated acid rain solution with the pH value of 4.5 into the conical flask, reacting at the temperature of 30 ℃, respectively oscillating for 2 hours, 4 hours, 8 hours, 24 hours, 48 hours and 72 hours at a constant speed (200rpm) by using an oscillator, sampling the mixture in the conical flask, and filtering and leaching the mixture (0.45 mu m filter membrane) to obtain the treated tailings leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Weighing 10.0g of certain lead-zinc ore tailings (YD), placing the tailings into a conical flask, adding 40mL of simulated acid rain solution with the pH value of 4.5 into the conical flask, reacting at the temperature of 30 ℃, respectively oscillating for 2 hours, 4 hours, 8 hours, 24 hours, 48 hours and 72 hours at a constant speed (200rpm) by using an oscillator, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane), and obtaining the treated tailings leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Weighing 10.0g of fresh tailings (CH1) of a tin polymetallic ore, placing the fresh tailings into an erlenmeyer flask, adding 40mL of simulated acid rain solution with the pH value of 4.5 into the erlenmeyer flask, reacting at the temperature of 30 ℃, shaking for 2h, 4h, 8h, 24h, 48h and 72h at a constant speed (200rpm) by using a shaker, sampling the mixture in the erlenmeyer flask, and filtering and leaching (with a 0.45-micron filter membrane) to obtain the treated tailings leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Weighing 10.0g of certain weathered tailings (CH2) of the tin polymetallic ore, placing the tailings into a conical flask, adding 40mL of simulated acid rain solution with the pH value of 4.5 into the conical flask, reacting at the temperature of 30 ℃, shaking for 2 hours, 4 hours, 8 hours, 24 hours, 48 hours and 72 hours at a constant speed (200rpm) by using a shaker, sampling the mixture in the conical flask, filtering and filtering (0.45 mu m filter membrane), and obtaining the treated tailings leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Weighing 10.0g of a tin polymetallic ore tailing deposit (CH3), placing the weighed deposit in an erlenmeyer flask, adding 40mL of simulated acid rain solution with the pH value of 4.5 into the erlenmeyer flask, reacting at the temperature of 30 ℃, shaking for 2h, 4h, 8h, 24h, 48h and 72h at a constant speed (200rpm) by using an oscillator respectively, sampling the mixture in the erlenmeyer flask, filtering and filtering (0.45 mu m filter membrane) to obtain the treated tailing leachate. And testing the concentration of the heavy metal ions in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Comparative example 2

Respectively weighing 1.0g of bentonite raw ore and 10g of lead-zinc ore tailings (F) to be uniformly mixed in a conical flask, respectively adding 40ml of simulated acid rain with the pH value of 4.5 into the conical flask, and oscillating at the temperature of 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentrations of the heavy metal ions Zn, Mn, As and Pb in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Respectively weighing 1.0g of bentonite raw ore and 10g of lead-zinc ore tailings (YD) to be uniformly mixed in a conical flask, respectively adding 40ml of simulated acid rain with the pH value of 4.5 into the conical flask, and oscillating for 4 hours at the temperature of 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentrations of the heavy metal ions Zn, Mn, As and Pb in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Respectively weighing 1.0g of bentonite raw ore and 10g of fresh tailings (CH1) of a certain tin polymetallic ore in a conical flask, uniformly mixing, respectively adding 40ml of simulated acid rain with the pH value of 4.5 in the conical flask, and shaking for 4 hours at the temperature of 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentrations of the heavy metal ions Zn, Mn, As and Pb in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Respectively weighing 1.0g of bentonite raw ore and 10g of weathered tailings (CH2) of a certain tin polymetallic ore in a conical flask, uniformly mixing, respectively adding 40ml of simulated acid rain with the pH value of 4.5 in the conical flask, and shaking for 4 hours at the temperature of 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentrations of the heavy metal ions Zn, Mn, As and Pb in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Respectively weighing 1.0g of bentonite raw ore and 10g of tin polymetallic ore tailing deposit (CH3) in a conical flask, uniformly mixing, respectively adding 40ml of simulated acid rain with the pH value of 4.5 in the conical flask, and shaking for 4 hours at the temperature of 30 ℃. After shaking at a constant speed (200rpm) for 4h with a shaker, the mixture in the erlenmeyer flask was filtered and filtered (0.45 μm filter membrane) to obtain a treated tailing leachate. And testing the concentrations of the heavy metal ions Zn, Mn, As and Pb in the treated tailing leachate by using an inductively coupled plasma mass spectrometer.

Test results

X-ray diffraction analysis was performed on the raw material calcium bentonite (Ca-Mt), the sodium bentonite obtained in step (1) of example 1, and the sulfide tailing treatment material obtained in step (3) of examples 1 to 4, respectively, and the XRD spectra were as shown in fig. 1A.

As shown in FIG. 1A, the d (001) value of the sodium bentonite (Na-Mt) is 1.24, while the d (001) values of the sulfide ore tailing treatment materials obtained in examples 1 to 4 are all larger than that of sodium bentonite and smaller than that of calcium bentonite (R-Mt), which indicates that all organic complexing agents are successfully intercalated between bentonite layers. In the four sulfide ore tailing treatment materials, the interlayer spacing between DA-Mt and TEPA-Mt is larger, and the interlayer spacing between DDTC-Mt is smaller.

SEM analysis was performed on the raw material calcium bentonite and the sulfide mine tailing treatment material obtained in step (3) of example 1, as shown in fig. 1B and 1C. As can be seen from FIGS. 1B and 1C, the DDTC-Mt surface has a distinct layered structure as compared with Ca-Mt, and these irregularities increase the surface roughness of DDTC-Mt. Furthermore, the DDTC-Mt surface is full of villous lumps, and the surface is stacked more densely compared with the Ca-Mt surface. From the corresponding EDS spectra, it can be seen that DDTC-Mt contains a large amount of C (see FIG. 1D), and DDTC contains a large amount of alkyl, indicating that DDTC has entered into sodium bentonite.

Measuring the concentrations of Zn, Mn, As and Pb in the filtrate by adopting an ICP-AES inductively coupled plasma mass spectrometer, and calculating the elution amount and the solidification rate of Zn, Mn, As and Pb: the solidification rate S (%) of the five tailing treatment materials to the heavy metals in the tailings is calculated by the following formula: s (%) - (C)₀-C_t)/C₀]X 100%, wherein C₀The unit is the cumulative dissolution concentration of the heavy metal in the tailings without adding the tailings treatment material, and the unit is mg/L; c_tThe unit of the accumulated dissolved concentration of the heavy metal after the tailing treatment material is added and solidified is mg/L. The ratio of the mass of the heavy metal accumulated dissolution of the tailings in the simulated acid rain to the mass m of the tailings is the accumulated dissolution quantity Q, the unit is mg/g, and the calculation formula of the accumulated dissolution quantity is as follows: q is C V/m, wherein C is the accumulated dissolution concentration of the heavy metal and has the unit of mg/L; v was 0.04L and m was 10 g.

In example 1, the solidification rate of DDTC-Mt to Zn in tailings is 87.09%, and the dissolution amount is 6.92 mg/Kg; the solidification rate of Mn in tailings is 34.49%, and the elution amount is 22.36 mg/Kg; the solidification rate of As in the tailings is 87.09%, and the elution amount is 0.80 mg/Kg; the solidification rate of Pb in the tailings is 38.31 percent, and the elution amount is 0.77 mg/Kg.

In examples 2-4, the graphs of the cumulative elution amounts of heavy metal Zn in tailings after different sulfide ore tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) are solidified for different reaction times (2h, 4h, 8h, 24h, 48h and 72h) are respectively shown in FIG. 2A; the graphs of the accumulated elution amounts of the heavy metal Mn in the tailings after different sulfide tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) are solidified for different reaction times (2h, 4h, 8h, 24h, 48h and 72h) are respectively shown in FIG. 2B. The graphs of the cumulative elution amounts of heavy metal As in the tailings after different sulfide tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) are solidified for different reaction times (2h, 4h, 8h, 24h, 48h and 72h) are respectively shown in FIG. 2C. The graphs of the cumulative elution amounts of heavy metal Pb in the tailings after different sulfide ore tailing treatment materials (DA-Mt, TTA-Mt and TEPA-Mt) are solidified for different reaction times (2h, 4h, 8h, 24h, 48h and 72h) are respectively shown in FIG. 2D.

From fig. 2A to fig. 2D, it can be seen that the cumulative elution amount of Zn, Mn, As and Pb in the cured tailings of the sulfide ore tailings within 72h is less than 0.02mg/g, the maximum curing rates of DA-Mt, TTA-Mt and TEPA-Mt to Zn can reach 99%, the maximum curing rates to Mn are 57%, 62% and 61%, respectively, the maximum curing rates to As are 88%, 99% and 96%, respectively, and the maximum curing rates to Pb are 63%, 95% and 90%, respectively.

In examples 5-9, the cumulative elution amount of heavy metal Zn after DDTC-Mt has cured for different times (2h, 4h, 8h, 24h, 48h, 72h) on different sulfide ore tailings (F, YD, CH1, CH2, CH3) is plotted as a graph, as shown in fig. 3A; the cumulative elution amount of the heavy metal Mn of the DDTC-Mt after different sulfide ore tailings (F, YD, CH1, CH2 and CH3) are solidified for different time (2h, 4h, 8h, 24h, 48h and 72h) is plotted as a graph, as shown in FIG. 3B; the cumulative elution amount of heavy metal As of the DDTC-Mt after different sulfide ore tailings (F, YD, CH1, CH2 and CH3) are solidified for different time (2h, 4h, 8h, 24h, 48h and 72h) is plotted As a graph, As shown in FIG. 3C; the cumulative elution amount of heavy metal Pb after different sulfide ore tailings (F, YD, CH1, CH2 and CH3) are solidified for different time (2h, 4h, 8h, 24h, 48h and 72h) by DDTC-Mt is plotted as shown in FIG. 3D.

As can be seen from FIGS. 3A to 3D, the cumulative elution amounts of the DDTC-Mt for the heavy metals after the solidification of different sulfide ore tailings are all lower than 25mg/Kg within 72 h; at the reaction time of 2h, the curing rates of DDTC-Mt to Mn in tailings CH1, CH2, CH3 and YD are respectively 89.11%, 72.25%, 53.21% and 77.91%, the curing rates to Zn in CH1, CH2 and CH3 are respectively 93.89%, 86.62% and 84.79%, and the curing rate to Pb in YD is 95.43%. As can be seen, the DDTC-Mt has good curing effect on different types of sulfide ore tailings.

The graph of the elution amount of the heavy metal Zn of five tailings which are not added with the tailing treatment material and are eluted in different time (2h, 4h, 8h, 24h, 48h and 72h) in the comparative example 1 is shown in figure 4A, the graph of the elution amount of the heavy metal Mn of five tailings which are not added with the tailing treatment material and are eluted in different time (2h, 4h, 8h, 24h, 48h and 72h) in the comparative example 1 is shown in FIG. 4B, the graph of the elution amount of the heavy metal As of the five tailings which are not added with the tailing treatment material and are eluted in different time periods (2h, 4h, 8h, 24h, 48h and 72h) in the comparative example 1 is shown in figure 4C, the graph of the elution amount of the heavy metal Pb of the five tailings which are not added with the tailing treatment material and are eluted in different time periods (2h, 4h, 8h, 24h, 48h and 72h) in the comparative example 1 is shown in FIG. 4D.

As can be seen from FIGS. 4A to 4D, heavy metals Zn, Mn, As and Pb are dissolved out to different degrees, and the maximum dissolution amounts of Zn, Mn, As and Pb in five kinds of sulfide ore tailings within 72 hours are respectively 63.23mg/Kg, 41.11mg/Kg, 5.37mg/Kg and 5.51mg/Kg, which exceed the national soil standard.

Comparative example 2 the cumulative elution amounts of heavy metals Zn, Mn, As and Pb after 4h of solidification of five tailings from bentonite raw ore were tested, and the results are shown in fig. 5. As can be seen from FIG. 5, the heavy metals Mn and Zn in the CH3 tailings and the F tailings are also dissolved out greatly.

Comparing the results, the curing effect of the four sulfide mine tailing treatment materials (DDTC-Mt, DA-Mt, TTA-Mt and TEPA-Mt) on the heavy metals in the tailings is similar, the release amount of the cured heavy metals is obviously lower than that of the tailings raw ores which are not cured by the tailings treatment materials, and the curing effect of the bentonite raw soil is not good.

Therefore, the bentonite is a good heavy metal solidification material, but the bentonite has limited cation exchange capacity between layers, so that the bentonite has a poor solidification effect on heavy metals in the sulfide tailings. In contrast, the bentonite raw ore is modified by the modifier, so that the cation exchange capacity of the bentonite raw ore is improved, the complexation between the bentonite raw ore and heavy metals is increased, and the solidification effect of the modified bentonite material on the heavy metals in the sulfide ore tailings is greatly improved under specific conditions. After certain lead-zinc mine tailings F are solidified by different sulfide mine tailing treatment materials DA-Mt, TTA-Mt and TEPA-Mt in 4 hours, the elution amounts of Zn, Mn, As and Pb are respectively reduced by more than 99%, 51%, 78% and 38%. After being solidified by DDTC-Mt for 4 hours, the elution amounts of Zn, Mn, As and Pb in the lead-zinc mine tailings F are respectively reduced from 53.57mg/Kg, 34.13mg/Kg, 3.36mg/Kg and 1.24mg/Kg to 6.92mg/Kg, 22.36mg/Kg, 0.80mg/Kg and 0.77 mg/Kg.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that the invention is described with reference to exemplary embodiments, but rather the words used therein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims

1. A method for treating heavy metal pollution in sulfide ore tailings comprises the following steps:

(1) preparing calcium bentonite and deionized water into a first turbid liquid with 5-7% of ore pulp concentration, stirring in a constant-temperature water bath at 60-75 ℃ to uniformly disperse, and adding solid Na₂CO₃Continuously stirring for 1-2 h to obtain a second suspension; wherein, solid Na₂CO₃The using amount of the bentonite is 1-5% of the mass of the calcium bentonite;

(2) aging the second suspension for 1-2 h, adding a modifier, stirring for 3-4 h in a constant-temperature water bath at 60-75 ℃, centrifuging for 20-30 min, washing and separating the obtained precipitate with deionized water, and repeating centrifuging and washing for multiple times to obtain modified bentonite; the modifier is selected from at least one of 1,6 hexamethylene diamine, triethylene tetramine, tetraethylene pentamine and sodium diethyldithiocarbamate, and the dosage of the modifier is 95mmol/100g of calcium bentonite;

2. The method according to claim 1, wherein in the step (1), the pulp concentration of the first suspension is 6%, and the first suspension is stirred in a constant-temperature water bath at 70 ℃ for 10-20 min.

3. The method of claim 1, wherein in step (1), solid Na is added₂CO₃Then stirring is continued for 90 min.

4. The method according to claim 1, wherein in the step (2), the temperature of the thermostatic water bath is 70 ℃, and the stirring time is 4 h.

5. The method of claim 1, wherein in step (2), the centrifuging and washing are performed a plurality of times by: and after supernatant liquid is removed by centrifugal separation, injecting deionized water into the precipitate obtained by separation for diluting to two times, uniformly stirring, performing centrifugal separation again, injecting water for diluting, and repeating for 3-5 times.

6. The method according to claim 1, wherein in the step (3), the drying time is 24-48 h.

7. The method of claim 1, wherein in step (3), the mill sieved particles are less than 200 mesh.

8. The method of claim 1, wherein in step (4), the sulfide tailings are mixed with the remediation material and simulated acid rain solution at 30 ℃.

9. The method of claim 1, wherein in step (4), the constant oscillation speed is 200 rpm.

10. The method of claim 1, wherein in step (4), the ratio of the sulfide tailings, the remediation material to the simulated acid rain solution is 10 g: 1 g: 40 mL.