RU2779420C1 - Method for purification of wastewater from iron and copper ions - Google Patents

Abstract

FIELD: wastewater purification.

SUBSTANCE: invention relates to methods for the chemical purification of wastewater from iron and copper ions using production waste with a high CaCO₃ content. According to the method, two parallel hydraulic structures are formed, which consist of a filtration section, a pond and a drainage system connected in series. The walls and bottom of the filtration section and the settling pond are made of compacted material, such as loam. The filtration section is completely filled with crushed production waste, which consists of 91 to 95% calcium carbonate with a particle size of 0.25 to 1.00 mm. The settling pond is filled with a sand and gravel mixture. Underdump water enters the filtration section, where the neutralization process takes place. Then, by gravity, it enters the settling pond, where iron and copper hydrocomplexes settle. Purified and clarified waters enter the recycling water supply of the enterprise, where the automated control of the composition of treated wastewater takes place. In case of insufficient water purification, the flow is switched to a parallel hydraulic structure.

EFFECT: increasing the efficiency of the degree of purification of wastewater from iron and copper ions and the rational use of production waste.

1 cl, 1 dwg, 4 tbl, 5 ex

Description

The invention relates to methods for the chemical treatment of wastewater from iron and copper ions using industrial waste with a high content of CaCO ₃ .

There is a known method for the purification of industrial wastewater from heavy metals (patent RU No. 2726121, publ. 07/09/2020), including step-by-step precipitation of heavy metals using alkaline components and subsequent precipitation, production wastes are used as components: limestone dust, dolomite drift dust , in addition, ferrosilicon microdust is used as an absorbent, the process is carried out in three stages: at the first stage, acid wastewater is neutralized in a reactor at a temperature of 70 ... 80 ° C to pH 4.0 ... dolomite to pH 7.0…8.0; at the second stage, the suspension is fed into an intermediate tank, ferrosilicon microdust is added, mixed thoroughly and then transferred to a radial settling tank, cooled to 25-30 ° C, treated effluents are separated into a treated wastewater tank, the remaining mixture is transferred to the third stage - to a combined dryer "fluidized bed", where it is simultaneously dried at a temperature of 130 ... 140 ° C and crushed to 10 ... 15 microns for 25 ... 30 minutes.

The disadvantage of this method is the presence of thermal operations that are difficult to control for the accepted conditions, such as acid effluent neutralization at a temperature of 70-80°C, suspension cooling to 25-30°C, cake drying at a temperature of 130-140°C.

There is a known method of purifying groundwater from heavy metals and oil products (patent RU No. 2712692, publ. 01/30/2020), including filtering groundwater in a geochemical barrier filled with mineral calcite, in which electrochemical power sources are placed that generate a coagulant, sediment extracted from the water being purified subjected to composting, the purified water is reused, characterized in that the water is filtered in a crossed electric field consisting of a transverse and longitudinal electric field created by electrochemical current sources located in series along the length of the geochemical barrier, and the direction of the electric field strength vector in neighboring electrochemical current sources is changed on the contrary, water filtered in mineral granular material is collected by perforated collectors located with a slope similar to the slope of water in a river, water is supplied to wells evenly spaced along the length of the geochemical barrier , which carry out the separation of oil products, water and sediment.

The disadvantages of this method is the need to use electrodes for the generation of coagulant and the requirement for their constant replacement.

A known method of water treatment (patent RU No. 2404926, publ. 27.11.2010), including the sequential passage of water through a mineral load containing a layer of shungite-3, a layer of limestone rock, a layer of shungizite, a layer of silicon-containing mineral rock, while water is supplied through the mineral load from bottom to top, moreover, dolomite and glauconite are used as separate layers of limestone rock, and marshalite is used as a silicon-containing mineral rock, and all minerals have a uniform particle size distribution with a granule size of not more than 5 mm and with a range of granule dimension within a difference of not more than 1 mm .

The disadvantages of this method is the need to use a large number of different materials to achieve a high degree of water purification without considering the possibility of their further disposal.

A known method for the precipitation of heavy non-ferrous metals from industrial solutions and/or effluents (patent RU No. 2601333, publ. 11/10/2015), including the treatment of solutions and/or effluents with a complex precipitant, including calcium carbonate, iron, oxides of silicon and magnesium in mass the ratio of CaCO ₃ : F _total . : SiO ₂ : MgO = 100:0.7-9.5:1.3-4.8:2.5-6.5, with active stirring to obtain a pH of 5.0-5.5 in the pulp, and subsequent exposure of the pulp with active stirring for 0.5-2 hours, filtration and washing of the precipitate, moreover, sludge from chemical water treatment of thermal power plants, including calcium carbonate, iron, silicon and magnesium oxides, is used as a precipitant, when their composition is adjusted to the specified ratio.

The disadvantages of this method is a complex process flow diagram, organization, control and maintenance of a system for active mixing of contaminated water with a precipitant, the multicomponent composition of the precipitant, the use of additional conditionally pure water for washing the precipitate.

A known method of wastewater treatment from ions of heavy nonferrous metals (patent RU No. 2191750, publ. 27.10.2002) adopted as a prototype, by draining wastewater through a layer of calcium-containing reagent, which is used as natural calcium carbonates, water purification is carried out due to the formation of basic sulfates against the background of gypsum-carbonate buffer (pH 6.4-6.5). The essence of the method lies in the self-regulation of the fine chemistry of precipitation in such a way that the concentration of carbonate ions in the solution is always less than the concentration of sulfate ions and there is no excess of hydroxide ions.

The disadvantages of this method include the need to maintain the concentration of carbonate ions in the solution in an amount always lower than the concentration of sulfate ions and the need to suppress the formation of excess hydroxide ions, which greatly complicates the application of the method; loss of valuable heavy non-ferrous metals with an excess of limestone, which does not ensure their recycling - the use of sediment for the subsequent extraction of metals.

The technical result is to increase the efficiency of the degree of purification of waste water from iron and copper ions and the rational use of production waste.

The technical result is achieved by pre-forming two parallel hydraulic structures, which consist of a series-connected filtration section, a pond and a drainage system, the walls and bottom of the filtration section and the settling pond are made of compacted material, which is used, for example, loam, compaction is carried out skating rink, then the filtration section is completely filled with crushed production waste, which consists of 91 to 95% of calcium carbonate with a particle size of 0.25 to 1.00 mm, and the settling pond is filled with a sand and gravel mixture, the underdump water enters the filtration section , where it passes through the layer with production waste and the process of neutralization takes place, then the underdump water flows by gravity into the settling pond, where iron and copper hydrocomplexes settle on the sand-gravel mixture, then the purified and clarified waters through the drainage system enter the circulating water supply of the enterprise, where there is an automated control of the composition of treated wastewater, in case of insufficient water treatment, the flow is switched to a parallel hydraulic structure.

The method of purification of wastewater from iron and copper ions is illustrated by the following figure:

figure 1 - scheme of waste water treatment, where:

1 - filtration section;

2 - metal mesh;

3 - compacted material;

4 - settling pond;

5 - sand and gravel mixture;

6 - drainage.

The method is carried out as follows. Two parallel hydraulic structures are formed, which consist of a filtration section connected in series, a settling pond and a drainage system.

Filtration section 1 (Fig. 1) is a trench that is passed using specialized equipment, such as an excavator. The parameters of the filtration section 1 are selected based on the volume of wastewater. The walls and bottom of the filtration section 1 are screened with compacted material 3, which is used, for example, loam or clay, with a filtration coefficient of not more than 0.005 m/day with a thickness of 300 to 500 mm. Shielding of the compacted material 3 is carried out using a roller.

Further, with the help of a jaw crusher, production waste is crushed, consisting of 91 to 95% of calcium carbonates to a particle size of 0.25 to 1.00 mm. The size of the production waste is set using production sieves. After that, the production waste is delivered to the location of the filtration section 1 using transport equipment. The filtration section 1 is completely filled with production waste by mechanical unloading.

Settling pond 4 is formed using an excavator. The parameters of the settling pond 4 are selected based on the volume of clarified water coming from the filtration section 1. The walls and bottom of the settling pond 4 are screened with compacted material 3, which is used, for example, loam or clay, with a filtration coefficient of not more than 0.005 m / day power from 300 to 500 mm. A layer of compacted material 3 is provided to prevent water filtration into the lower soil layers. Shielding of the compacted material 3 is carried out using a roller. Then the settling pond 4 is filled with a sand-gravel mixture 5, with a particle size of 10 to 70 mm by mechanical unloading. The thickness of the layer of sand-gravel mixture 5 depends on the parameters of the settling pond 4 and ranges from 20 to 25% of the total volume of the settling pond 4.

Drainage 6 is a pipe made of non-corrosive material, the diameter of which is selected based on the volume of clarified water flowing by gravity from the settling pond 4. Drainage 6 is located in the soil layer below the upper boundary of the settling pond 4 at a depth that provides an arbitrary overflow of clarified water as it is filled settling pond 4. The formation of a trench for laying the drainage system and the subsequent backfilling of the drainage pipe is carried out using an excavator. One of the ends of the drainage system 6 goes into the settling pond 4. The other end of the drainage system 6 is located at the place of the intended exit of the treated wastewater into natural streams or reservoirs, or is brought into water storage tanks for further needs of enterprises.

Underdump water enters the filtration section 1, completely filled with production waste, consisting of 91 to 95% of calcium carbonates, with a particle size of 0.25 to 1.00 mm. When the loading of the filtration section 1 interacts with the dump waters, they are neutralized - the reaction of the interaction of an acid and a base with each other with the formation of a salt and a weakly dissociating substance. Underdump waters are characterized by low pH values, are acidic and slightly acidic, and production waste, consisting of 91-95% of calcium carbonates, when exposed to water and carbon dioxide, turns into soluble calcium bicarbonate, which is then hydrolyzed to form calcium hydroxide, which is a strong base (alkali). Thus, the base in the form of calcium hydroxide neutralizes acidic wastewater with an increase in pH from 6 to 7. Chemical precipitation of copper and iron in the form of hydroxides occurs by the exchange interaction of metal ions with calcium hydroxide. Iron and copper hydroxides are crystalline substances. Iron (II) hydroxide is insoluble in water, and copper hydroxide is practically insoluble.

After passing through the filtration section, the neutralized wastewater flows by gravity into the settling pond 4, where iron and copper hydroxides are settled, while the sand and gravel mixture, with a particle size of 10 to 70 mm, located in the settling pond, is a mechanical filter for retaining the precipitated hydroxides of iron and copper, this contributes to the purification of waste water from iron and copper.

After settling, as the settling pond 4 is filled, the purified and clarified waters through the drainage system 6 enter the recycling water supply of the enterprise. In the circulating water supply system, an automated control of the composition of treated wastewater (not shown in the figure) takes place, and in case of insufficient purification from iron and copper, the wastewater runoff is switched to parallel hydraulic structures.

After the end of the filtration process from the filtration section and the settling pond, production waste and sand-gravel mixture 5 with sediment are removed by a bucket excavator. Further, the production waste and the sand-gravel mixture with sediment are naturally dried in an open area, after which some of them can be transported by trucks to the existing tailings in order to strengthen the slopes, and some - to the processing plant of the enterprise in order to additionally extract useful components.

After the release of the filtration section 1 and the settling pond 4 from contaminated production waste and sand and gravel mixture, the filtration section 1 is completely filled with production waste, consisting of 91-95% CaCO _3, with a particle size of 0.25 to 1.00 mm, and the settling pond 4 is filled with sand-gravel mixture 5 by 20-25% of the total volume, depending on the parameters of the settling pond 4. After that, the waste water flow can be switched back to this parallel of hydraulic structures.

The method is illustrated by the following examples.

To evaluate the developed technology for experiments, a model solution of dump water with a pH of 2 to 3 was used, containing a solution of copper sulfate and iron with an iron concentration of at least 400 mg/l and at least copper 200 mg/l.

Example 1. As a filtration material for the filtration section, a waste product from the Novolipetsk Iron and Steel Works, the city of Lipetsk, with a CaCO ₃ content of 91-93%, was chosen. To fill the settling pond, a sand-gravel mixture from Field 27, Vyborgsky District, Leningrad Region, with a particle size of 30 to 60 mm, was used.

The production waste was subjected to crushing in a jaw crusher. Further, the production waste was subjected to fractional analysis using laboratory sieves. A sample of production waste of each size was placed in a laboratory model of a filtration section, the length of which was 0.3 m, width - 0.7 m, height - 0.02 m. At the same time, the laboratory model of the filtration section was separated from the laboratory model of the settling pond with a metal mesh. The settling pond was modeled in the following dimensions: length - 0.9 m, width - 0.7 m, height - 0.025 m. The settling pond was filled with sand-gravel mixture for 20-25% of the total volume.

The model solution of waste water was passed through the filtration section at a rate of 0.00017 m ³ /h. Further, the solution was settled in a laboratory model of a settling pond, after which it was collected through a drainage model for further analysis.

The model solution was filtered through 1 layer of a blue ribbon filter with a pore diameter of 1–2.5 nm. Measurement of the concentration of iron and copper was carried out on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory of the Center for the Collective Use of High-Technological Equipment of the St. Petersburg Mining University.

Table 1 shows the data on the content of iron and copper before and after cleaning, indicating the size of the production waste.

Table 1. Results of pH and concentrations of iron and copper before and after cleaning Waste size, mm pH before purification pH after cleaning Initial concentration of Cu ²⁺ , mg/l Concentration of Cu ²⁺ after cleaning, mg/l Initial concentration of _Fetot , mg/l The concentration of _Fetot after cleaning, mg/l <0.25 3.0 6.8 200 14.3 400 99.7 0.25-0.5 <0.05 12.7 0.5-1.0 12.3 14.8 1.0-2.0 28.7 114.0 2.0-5.0 39.7 126.0 >5.0 61.6 178.0

As can be seen from the table, the use of production waste with a CaCo3 content of 91-93% for cleaning model solutions from iron and copper ions showed the highest efficiency with a waste size of 0.25-0.5 and 0.5-1.0.

Example 2. As a filtration material for the filtration section, a waste from the production of the Limestone Quarry of the Ural Mining and Metallurgical Company, the city of Sibay, with a CaCO ₃ content of 92-94%, was chosen. To fill the settling pond, a sand-gravel mixture was used from the quarry of MEZHREGIONPROEKT LLC, Vyborgsky district of the Leningrad region, with a particle size of 20-50 mm.

The production waste was subjected to crushing in a jaw crusher. Further, the production waste was subjected to fractional analysis using laboratory sieves. A sample of production waste of each size was placed in a laboratory model of a filtration section, the length of which was 0.3 m, width - 0.7 m, height - 0.02 m. At the same time, the laboratory model of the filtration section was separated from the laboratory model of the settling pond with a metal mesh. The settling pond was modeled in the following dimensions: length - 0.9 m, width - 0.7 m, height - 0.025 m. The settling pond was filled with sand-gravel mixture for 20-25% of the total volume.

The model solution of waste water was passed through the filtration section at a rate of 0.00017 m ³ /h. Further, the solution was settled in a laboratory model of a settling pond, after which it was collected through a drainage model for further analysis.

The model solution was filtered through 1 layer of a blue ribbon filter with a pore diameter of 1 to 2.5 nm. Measurement of the concentration of iron and copper was carried out on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory of the Center for the Collective Use of High-Technological Equipment of the St. Petersburg Mining University.

Table 2 shows the data on the content of iron and copper before and after cleaning, indicating the size of the production waste.

Table 2. Results of pH and concentrations of iron and copper before and after cleaning Waste size, mm pH before purification pH after cleaning Initial concentration of Cu ²⁺ , mg/l Concentration of Cu ²⁺ after cleaning, mg/l Initial concentration of _Fetot , mg/l The concentration of _Fetot after cleaning, mg/l <0.25 2.8 6.5 200 120.0 400 212.0 0.25-0.5 0.12 16.9 0.5-1.0 15.7 29.8 1.0-2.0 82.3 154.7 2.0-5.0 173.0 251.0 >5.0 175.0 273.9

As can be seen from the table, the use of production waste with a CaCo3 content of 92 to 95% for the purification of model solutions from iron and copper ions showed the highest efficiency at a waste size of 0.25-0.5 and 0.5-1.0.

Example 3. Waste production from the Pugachev quarry, the Republic of Bashkortostan, with a CaCO3 content of 92-95% was chosen as a filtration material for filtration sections. To fill the settling pond, a sand-gravel mixture from Field 27, Vyborgsky District, Leningrad Region, with a particle size of 30 to 70 mm, was used.

The production waste was subjected to crushing in a jaw crusher. Further, the production waste was subjected to fractional analysis using laboratory sieves. A sample of production waste of each size was placed in a laboratory model of a filtration section, the length of which was 0.3 m, width - 0.7 m, height - 0.02 m. At the same time, the laboratory model of the filtration section was separated from the laboratory model of the settling pond with a metal mesh. The settling pond was modeled in the following dimensions: length - 0.9 m, width - 0.7 m, height - 0.025 m. The settling pond was filled with sand-gravel mixture for 20-25% of the total volume.

The model solution of waste water was passed through the filtration section at a rate of 0.00017 m ³ /h. Further, the solution was settled in a laboratory model of a settling pond, after which it was collected through a drainage model for further analysis.

The model solution was filtered through 1 layer of a blue ribbon filter with a pore diameter of 1–2.5 nm. Measurement of the concentration of iron and copper was carried out on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory of the Center for the Collective Use of High-Technological Equipment of the St. Petersburg Mining University.

Table 3. Results of pH and concentrations of iron and copper before and after cleaning Waste size, mm pH before purification pH after cleaning Initial concentration of Cu ²⁺ , mg/l Concentration of Cu ²⁺ after cleaning, mg/l Initial concentration of _Fetot , mg/l The concentration of _Fetot after cleaning, mg/l <0.25 2.9 6.7 200 113.0 400 151.2 0.25-0.5 0.51 14.8 0.5-1.0 16.9 25.2 1.0-2.0 69.5 133.3 2.0-5.0 121.0 203.6 >5.0 133.0 226.1

Example 4. As a filtration material for the filtration sections was chosen waste from the production of a quarry "Western", Leningrad region, with a CaCO ₃ content of 91 to 94%. To fill the settling pond, a sand-gravel mixture was used from the quarry of MEZHREGIONPROEKT LLC, Vyborgsky district of the Leningrad region, with a particle size of 10 to 40 mm.

The production waste was subjected to crushing in a jaw crusher. Further, the production waste was subjected to fractional analysis using laboratory sieves. A sample of production waste of each size was placed in a laboratory model of a filtration section, the length of which was 0.3 m, width - 0.7 m, height - 0.02 m. At the same time, the laboratory model of the filtration section was separated from the laboratory model of the settling pond with a metal mesh. The settling pond was modeled in the following dimensions: length - 0.9 m, width - 0.7 m, height - 0.025 m. The settling pond was filled with sand-gravel mixture for 20-25% of the total volume.

The model solution of waste water was passed through the filtration section at a rate of 0.00017 m ³ /h. Further, the solution was settled in a laboratory model of a settling pond, after which it was collected through a drainage model for further analysis.

The model solution was filtered through 1 layer of a blue ribbon filter with a pore diameter of 1 to 2.5 nm. Measurement of the concentration of iron and copper was carried out on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory of the Center for the Collective Use of High-Technological Equipment of the St. Petersburg Mining University.

Table 4. Results of pH and concentrations of iron and copper before and after cleaning Waste size, mm pH before purification pH after cleaning Initial concentration of Cu ²⁺ , mg/l Concentration of Cu ²⁺ after cleaning, mg/l Initial concentration of _Fetot , mg/l The concentration of _Fetot after cleaning, mg/l <0.25 2.9 6.8 200 108.0 400 148.9 0.25-0.5 0.49 14.6 0.5-1.0 17.1 23.9 1.0-2.0 73.3 128.8 2.0-5.0 118.5 187.4 >5.0 128.4 222.1

Example 5. Waste from the production of the Pugachev quarry, the Republic of Bashkortostan, with a CaCO3 content of 92-95% was chosen as a filtration material for the filtration sections. To fill the settling ponds, a sand-gravel mixture was used from the quarry of MEZHREGIONPROEKT LLC, Vyborgsky district of the Leningrad region, with a particle size of 10 to 70.

The production waste was subjected to crushing in a jaw crusher to a particle size of 0.25 to 1.00 mm. Production waste was filled with two parallel laboratory models of filtration sections with the following parameters: length - 0.3 m, width - 0.7 m, height - 0.02 m. sand and gravel mix. Parameters of settling ponds: length - 0.9 m, width - 0.7 m, height - 0.025 m. At the same time, laboratory models of filtration sections were separated from laboratory models of settling ponds with a metal mesh.

The model solution of waste water was passed through the filtration section at a rate of 0.00017 m3/h. Further, the model solution was settled in a laboratory model of a settling pond, after which it was discharged through the model and the drainage system.

After filling the entire volume of the settling pond, the model solution was passed through a parallel laboratory model of the filtration section, from where it entered the parallel laboratory model of the settling pond for settling. After settling, clarified and purified water was discharged through the drainage model.

Production waste and sand-gravel mixture with sediment were removed from the filtration section and the settling pond that were not used in the method, which were then dried naturally.

This example showed the possibility of using two parallel hydraulic structures to remove and replace contaminated production waste and sand-gravel mixture with uncontaminated ones. Contaminated production waste and sand and gravel mixture can be used to strengthen the slopes of tailings or to recover useful components.

At least two parallel hydraulic structures can also be used during an increase in the volume of treated water, for example, the spring period of snowmelt, increased precipitation, etc.

The use of this method of waste water treatment allows to purify waste water from iron and copper ions with a high degree of 91 to 99% using production waste with a CaCO ₃ content of 91-95%, a particle size of 0.25 to 1.0 mm and sand and gravel mixtures, particle size from 10 to 70 mm as a mechanical filter. At the same time, the use of at least two hydraulic structures in the method makes it possible to remove contaminated production waste and sand-gravel mixture together with the sediment of copper and iron hydro complexes to further strengthen the slopes of tailings or to recover useful components.

Claims (1)

A method for cleaning wastewater from iron and copper, including the precipitation of metals by draining wastewater through a layer of crushed calcium carbonates, characterized in that two parallel hydraulic structures are preliminarily formed, which consist of a filtration section connected in series, a pond and a drainage system, the walls and bottom of the filtration sections and a settling pond are made of compacted material, for example, loam, compaction is carried out with a roller, then the filtration section is completely filled with crushed production waste, which consists of 91 to 95% calcium carbonate size from 0.25 to 1.00 mm, and the settling pond is filled with sand and gravel mixture, the underdump water enters the filtration section, where it passes through the layer of production waste and the neutralization process takes place, then the underdump water flows by gravity into the settling pond, where there is a settling of iron and copper hydrocomplexes on the sand-gravel mixture, then the purified and clarified waters through the drainage system enter the recycling water supply of the enterprise, where the automated control of the composition of the treated waste water takes place, in case of insufficient water purification, the flow is switched to a parallel hydraulic structure.

Images