RU2497759C2 - Method of purifying industrial sewages from heavy metals - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be applied at enterprises of ferrous and non-ferrous metallurgy, chemical industry for purification of industrial sewages, for example, for extraction of heavy metals from acid and subacid sewages with high content of heavy metals. To realise the method processing of sewages with liquid alkaline peat-humic preparation is performed with its ratio to solution of industrial sewages from 1:100 to 1:1000. Formed sediment of metal-organic complexes is separated from purified technogenic solutions and subjected to thermal enrichment of sediment by annealing at temperature 450-600°C.

EFFECT: ensuring effective purification of industrial sewages from ecologically dangerous elements - heavy metals and extraction of useful components, ie realising complex industrial recycling of industrial sewages.

2 dwg, 2 tbl

Description

The invention relates to the field of metallurgy and purification of industrial wastewater, in particular to methods for purification and extraction of heavy metals from acidic and slightly acidic industrial wastewater with a high content of heavy metals, and can be used in enterprises of ferrous and non-ferrous metallurgy, chemical industry and other industries .

Various reagents, such as carbonate rocks, activated carbon, zeolites, soda, iron hydroxides, cogeneration ash, cellulose, humic acids, humates of potassium and ammonium, etc. are used to reduce the anthropogenic impact of mining and processing waste products [Chockalingam E., Subramanian S .- Chemosphere, 2006, 62, 699-708; Cravotta C.A., Ward S.J. -.Mine Water Environ. 2008, 27, 67-85; Gabr M.A., Bowders J.J. - J Hazard Mater, 2000, 76, 251-263; Kumar Vadapalli V.R. et al. - S Afr J Sci, 2008, 104: 317-324; Lee et al. - Chemosphere, 2004, 56, 571-581; Nogueira da Silveira A. et al. - Int J Miner Process, 2009, 93, 103-109; Perrez-Lorpez R. et al. - Chemosphere, 2007, 67, 1637-1646; Ri'os et al. - J Hazard Mater, 2008, 156, 23-35; JP 52-29996, publ. 08/05/77, B01D 15/00; Patent SU 1758023, publ. 08/30/92 C02F 1/62], various screens [Sergeev V.I. et al. - Wat Sci Tech, 1996, 34 (7-8), 383-387; Doncheva A.V., Pokrovsky S.G. - Fundamentals of environmental production technologies / M.: Publishing house of Moscow State University, 1999, 108 pp .; Maximovich N.G., Blinov S.M. - Proc, 7th International Congress of the Assoc of Engineering Geology, Lisboa, Portugal, 1994, 3159-3164; Maximovich N.G. et al. - Proc. Conf on Protection of Groundwater from Pollution and Seawater Intrusion, Bari, Italy, 1999, 14. et al.) And microbial communities (Benner SG et al. - Chem Geol, 1999, 169, 435-448; Sandstrom A. et al. - Inter J Miner Process, 2001, 62, 309-320, etc.], which are not always effective, for example, many waste disposal methods involve introducing chemicals into wastewater solutions and adjusting the pH to values from which the solutions heavy metal hydroxides precipitate.The precipitate from heavy metal hydroxides and impurities of reagents is sometimes disposed of by sintering it with glass and firing with ceramic mass since without treatment of precipitation, when changing pH, heavy metals transform into mobile forms, polluting the environment. Unfortunately, it is known that for heavy metals in principle there are no reliable self-cleaning mechanisms. These elements are only redistributed from one natural reservoir to another [Mur J .V., Ramamurti S. - Heavy metals in natural waters / Moscow: Mir, 1987, 250 pp.]. The main disadvantage of industrial wastewater treatment methods is that eventually new waste is generated, such as precipitation of heavy metal hydroxides, which also need to be disposed of.

In this regard, the most promising is the extraction of non-ferrous metals and iron from acidic wastewater, both from an economic and environmental point of view. Currently, the extraction of non-ferrous metals from mine water is carried out by cementation and extraction methods followed by electrolysis [Bunce N.J et al. - Water Res., 2001, 35 (18), 4410-4416 and others], sorption leaching on ion-exchange resins [Laskorin B.N. And others. Non-waste technology in industry / M .: Stroyizdat, 1986, - 160 p.], Sorption on cellulose-containing sorbents [patent RU 2351548, publ. 04/10/2009, C02F 1/62], using a precipitate of acaganeite nanocrystals [patent RU 2323988, publ. 09/27/2005, C22B 30/04].

Humic acids are a universal sorbent for all types of heavy metals in cationic form, since they form strong compounds with metal ions and, therefore, can act as powerful absorbers [Orlov DS, Humic acids of soils and the general theory of humification. / Moscow: Publishing House of Moscow State University, 1990; Varshal G.M. and others / Humic substances in the biosphere, 1993, p.97-117; Bannikova L.A. Organic matter in hydrothermal ore formation / M .: Nauka, 1990, 207 s; Perminova I.V. - Chemistry and life, 2008, 1, p. 51-55; Kholin Yu.V. - UNIVERSITATES Journal, Ukraine, Kharkov, 2001, 4, p.21-25. and etc.]. Ecotoxicants irreversibly bind to the functional groups of humic acids (carboxylic, hydroxyl, carbonyl, amide, etc.), forming the solid phase of organic complexes. In the future, sorption of residual cations on the developed surface of colloids by active centers is possible. For example, a known method of neutralization and wastewater treatment [patent RU 2174107 published 09/27/2001, C02F 1/66], in which wastewater from heavy metal ions of one type with a high concentration, is carried out in two stages, with the first stage waste water is treated with a peat-alkaline reagent with a mass ratio of heavy metal ions of the same type to a peat-alkaline reagent as 1- (1-1.3), in which the peat-alkaline reagent is a filtrate solution of caustic soda, passed through peat granules. Next, the treated wastewater is mixed and sedimented to a pH of 6.4–6.95, and in the second stage they are treated with milk of lime to a pH of 8.75–9.25, with stirring and settling, with the separation of the precipitate formed and subsequent discoloration. The disadvantage of this method is that the ratio of heavy metal ions of the same type to peat-alkaline reagent = 1- (1-1.3) is large enough, which can lead to pollution of effluents with organic compounds, for example, fulvic acids. Also, the use of caustic soda in large quantities to produce a peat-alkaline reagent or the use of high ratios of reagent / waste water can lead to sodium pollution of the water. The most important thing is that in this method the environmental problem is not completely solved, since the precipitate must be disposed of. A known method of producing treatment sludge containing wastewater metals, which consists in neutralizing acidic waters with alkaline waters with a pH of 10-12 to a pH of 6.0-8.5 into which humic acids of sapropels and peat are introduced, the resulting slurry of metal chelating compounds is dried at a temperature of no higher than 150 ° C and the obtained friable product is pressed at room temperature under pressure, providing a briquette [patent RU 2096349, publ.: 20.11.1997, C02F 11/12, C02F 1/62]. The resulting sludge does not contain toxic metal hydroxides, since in the process of neutralization of acidic waters containing metals, water and sludge are formed from chelated (intra-complex) compounds. A polyatomic molecule of a chelate compound with symmetrically located functional groups is not polar and has a weak intermolecular bond, which makes dried sludge loose and pressed into briquettes. This allows you to organize the effective storage of sludge in warehouses intended for the storage of chemicals, eliminating environmental pollution. Such storage is more efficient than the disposal of metal hydroxide sludge, occupying large land plots and creating a risk of environmental pollution. But again, this method generates waste (sludge) for which storage is needed. Known gum-mineral reagent from natural humites and caustobioliths of a coal series, containing humic acids and salts of humic acids, used for detoxification of waste mining and processing of minerals and disposal of precipitation [patent RU 2233293, IPC: C02F 1/54, publ. 07/27/2004]. When treating wastewater using this reagent, heavy metal ions are bound by humic acids and humates according to the type of ion exchange with the formation of water-insoluble compounds. Then calcium hydroxide is introduced, while humates and water-soluble humic acids interact with calcium and form a water-insoluble calcium humate, which filters the water and removes contaminated impurities from it. The treated water is defended, the water is drained, and the precipitate is removed and dehydrated. The dehydrated sludge is burned at a temperature of 800 ° С, at this temperature humic substances decompose without the formation of harmful compounds. The dehydrated sludge is composted and valuable fertilizer obtained. The disadvantage of this method, as well as the previous ones, is a rather high amount of a humic-mineral reagent (1-7% by weight of wastewater) introduced into the wastewater. In addition, at a temperature of 800 ° C, secondary pollution of the environment with harmful impurities volatile at such high temperatures is possible. Thus, this method also does not completely solve the environmental problem.

The authors of the present invention previously developed a method for purifying acidic wastewater of the mining industry using a peat-humic preparation. Using methods of chemical, mechanochemical and barothermic effects on peat, an alkaline peat-humic preparation is obtained that differs from the original peat by a higher (three times) content of humic acids and, consequently, an increase in functional groups [Bogush A.A., Voronin V.G. - Mine Water Environ J. / Springer Online first, 2010, DOI: 10.1007 / s10230-010-0132-2]. Examples of wastewater treatment of various mining enterprises, such as. The Old Vault of Gornyak, Altai Territory, the Karabash Copper Smelter of the Chelyabinsk Region, the Belovsky Hydro Dump of the Kemerovo Region, the Ursk Tailings of the Salair Gold Extraction Plant and others show that using acid solutions of alkaline peat-humic preparation, it is possible to bind up to 70-99% of metals from industrial wastewater in organometallic complexes. The necessary addition of a peat-humic preparation for the greatest extraction effect depends on the composition and characteristics of the wastewater and can be calculated after conducting preliminary experiments for specific technogenic waters.

It was also shown that the pH of the resulting solutions increases, since acidic wastewater is neutralized by using an alkaline peat-humic preparation with a pH of 12. The pH value changes to the alkaline region the more, the greater the addition of reagent. Organometallic complexes formed in the form of a flocculent precipitate - insoluble humates of heavy metals can be removed by filtration through activated carbons or expanded clay. In this way, it is possible to reduce the concentration of potentially toxic elements to very low values. However, this method is not without drawbacks, since the resulting solid precipitation of humates must also be disposed of.

The objective of the invention is to develop an integrated method for the treatment of industrial wastewater from heavy metals using an alkaline peat-humic preparation.

The technical result is that it is possible to achieve two goals at once: to ensure the effective treatment of industrial wastewater from environmentally hazardous elements and to ensure the extraction of useful components (heavy metals), i.e. carry out industrial processing of industrial effluents, as well as reduce the cost of waste disposal.

The problem is achieved in that in a method for purifying industrial wastewater from heavy metals by converting metals to organometallic complexes by treating wastewater with an alkaline peat-humic preparation with a volume ratio of peat-humic alkaline preparation to an industrial solution from 1: 100 to 1: 1000 (in depending on the composition of wastewater) and the separation of the precipitate of organometallic complexes from the purified solution, the precipitate formed is subjected to thermal enrichment by annealing at a temperature of 450-600 ° C.

At these temperatures, it is possible to completely remove organic matter from organometallic complexes and to obtain metals in the form of inorganic compounds, mainly in the form of oxides and sulfates. At lower temperatures, residues of organic matter are observed in the sample, and the use of higher temperatures leads to the volatilization of some useful components and is unprofitable from an economic point of view, since it is necessary to spend more energy. The substance after calcination mainly consists of metal oxides, which can then be used to obtain pure metals (blast furnace process, pyrometallurgy, hydrometallurgy, etc.). This technology is simple, economical, efficient and affordable for industrial enterprises.

Figure 1 presents a diagram of the extraction of metals from industrial wastewater.

Figure 2 - data from a JSM-36 electronic scanning microscope (JEOL company) with a KEVEX energy dispersion attachment for the study of solids after calcining a precipitate of organometallic complexes formed by treatment of drainage water with an alkaline peat-humic preparation (TGP). The method is as follows. Highly concentrated industrial wastewater is pumped into special sumps. We used a peat-humic preparation with pH 12 based on peat from the Krugloye deposit (Kochenevsky district. Novosibirsk region), treated by chemical, mechanochemical, and barothermic methods [Bogush AA, Voronin VG (2010)]. Depending on the composition and characteristics of the wastewater, it is recommended to use a volume ratio of alkaline peat-humic preparation to an industrial solution from 1: 100 to 1: 1000. A solution of peat-humic preparation is added to the sumps with vigorous stirring. Table 1 shows the initial metal content (mg / l) and pH of the solutions in the wastewater of various mining and processing enterprises. Table 2 - the degree of purification of industrial wastewater (%) and the pH of the treated water. Then, two methods of separation of the formed organometallic precipitate are used: filtration through industrial filters and subsequent washing of the precipitate or sedimentation of solutions, and then pumping of purified water. The precipitates thus obtained are thermally treated at a calcination temperature of 450-600 ° C. to remove organic matter and obtain the oxides of the corresponding metals. The substance after calcination mainly consists of metal oxides, for example, hematite (Fe ₂ O ₃ ) was determined after wastewater treatment at Altaypolimetal JSC and the Ursk tailings, as well as tenorite (CuO) after wastewater treatment at the Belovsky hydraulic dump using X-ray diffraction analysis (powder) radiography on a DRON-3M device with CuKα radiation). Using a scanning electron microscope, it was shown that after calcining precipitates at a temperature of 450-600 ° C, it is an agglomerate consisting of metal oxides with an admixture of various elements, as well as calcium sulfate (figure 2).

Table 1 The metal content (mg / l) and the pH of the solutions in the wastewater of the mining and processing industries Sample Name pH Fe Al Cu Zn Pb Cd Ni Co Drainage water of the Old Vault (Gornyak city) 2.7 210 350 37 160 0.4 0.86 0.56 0.81 Lake at the Old Vault (Gornyak) 2.4 450 620 90 270 0.44 2.3 - - Drainage water of the New Storage (Gornyak) 3.4 9.3 77 twenty 94 0.56 0.46 - - Belovsky drainage water (Belove) 4.1 0.18 21 730 910 - 6.0 5.9 5.1 Belovsky hydraulic dump (Belove city) 4.8 0.22 eighteen 270 120 - 1.2 0.68 0.6 Drainage waters of the Karabash smelter (Karabash) 3.6 8.8 31 59 eighteen - 0.06 0.18 0.13 Drainage waters of the Ura tailings 2.97 1700 600 5.0 23 - 0.03 - - MPC (SanPiN, 2.1.4.559-96) - 0.3 0.5 1.0 5.0 0.03 0.001 0.1 0.1

table 2 The degree of purification of industrial wastewater (%) and the pH of the treated water Sample Name pH Fe Al Zn Cu Pb Cd Ni With A1 (G1) 2.9 21 17 fourteen 8 98 eleven 17 5 A2 (G1) 3.1 36 26 twenty 35 98 43 40 21 A3 (G1) 3.7 74 66 58 95 98 99 95 85 A1 (B1) 5.1 95 60 eleven eleven - 13 3 8 A2 (B1) 5.3 95 99 21 23 - 23 fifteen eighteen A3 (B1) 6.2 95 99.9 67 71 - 80 75 76 A1 (B2) 6.4 94 66 60 52 - 8 24 22 A2 (B2) 7.1 94 99.9 96 99 - 76 61 57 A3 (B2) 8.2 94 99.9 99.9 99.9 - 99.9 89 94 Note: G1 - Drainage waters of the Old Storage (Gornyak), B1 - Belovsky drainage waters (Belove), B2 - Belovsky hydraulic dump (Belove), A1 - TGP: drainage water = 1: 1000; A2 - TGP: drainage water = 1: 500; A3 - TGP: drainage water = 1: 100.

Claims (1)

A method of purifying industrial wastewater from heavy metals, including treating wastewater with an alkaline peat-humic preparation and separating the treated water, characterized in that a liquid alkaline peat-humic preparation is used with a ratio of 1: 100 to 1: 1000 to an industrial wastewater solution , the resulting precipitate of organometallic complexes is subjected to thermal enrichment by annealing at a temperature of 450-600 ° C.

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