LT2010015A - Method of processing iron-containing sludge into pigmented material - Google Patents

Abstract

The present invention relates to the field of industrial ecology. It deals with the process in which sludge, recovered in waste water treatment by hetero-coagulation is converted into red, redbrown pigment material. At first sludge is treated by phosphoric acid and afterwards by water-soluble zinc salt, and partly by zinc sulfate in the molecular ratio of Fe2O3 to ZnO as 1 to 0,1-0,3; the obtained mixture is homogenised, dried and thermally treated at the temperature of 800-850 oC.@

Description

1

METHOD OF PROCESSING OF IRON WITH PLASTIC MATERIAL \ t

The present invention relates to the field of industrial ecology, and more specifically to the processing of iron-containing sludge obtained from the treatment of heterocoagulating wastewater from heavy metals to red-brown pigment.

Wastes containing heavy metal ions (Zn2 +, Cr6 +, Cu2 +, Fe2 +, Fe3 +, Ni2 +, etc.) are mostly produced in the production of non-ferrous metals, in the formation of galvanic coatings on plastic and metal surfaces, in the metal etching process, in the processing of printing plates, and so on. Decontaminated waters are discharged into the sewer, but there is a galvanic sludge that is saturated with the above-mentioned heavy metals. According to the EBT Waste Framework Directive 75/442 / EEC of 15 July 1975, heavy metals are classified as hazardous waste because they can adversely affect the living organism when entering the surrounding environment.

This is why the problem of the utilization of sludge containing heavy metal ions remains important worldwide. The countries of the European Community are required to follow the guidelines for the management of hazardous waste. EBT Directive 91/689 / EEC. Of course, the technology of wastewater treatment of heavy metals [patent no. 4109 B, TPK 6 C02F 1/62 publ. 1997-02-25] using a suspension of ferric ferrihydrazole (FFH), which is iron II) and a suspension of (III) oxyhydrates. When it comes to wastewater treatment, there is a sludge with a high content of iron compounds (more than 60% of dry matter). This makes it possible to efficiently recycle sludge and obtain inorganic iron pigments from it [EyzmJiOBCKHc JĘ, EyanjioBCKHc 10., Ememco JI. C. // XnMHHecKoe h He (j) Tera30Boe ManiHHOCTpoeHHe. N ° 11, 2004, c. 36-38], Known natural mineral iron-containing pigments with a sufficiently wide range of colors, the color of which is determined by the presence of iron oxide in the mineral. For example, the mixed iron (II) and (III) oxide (ferric tetraoxide) - Fe304 - is black and found naturally in the form of mineral magnetite. Ferrous trioxide (a Fe 2 O 3) is a red pigment. It has pigments like Persian Red (75% Fe203) and Spanish Red (85% Fe203). Depending on the shape and size of 3 particles of Fe2C > the color may vary from orange to violet-red. It is found in nature in the form of red mineral hematite (a Fe 2 O 3) [The Merck Index, 14 Edition / publ. Merck & Co.Inc., White House Station, NJ, 2006, Table-63; KopcyHCKun JI. J., KaJiHHCKaa T. B., ΟτεπηΗ C. H. // HeopraHHuecKHe ΠΗΓΜεΗΤΗ: CnpaBOHHHK. CIT6 .: Χημηη, 1992, 336]. 2 A well-known and widely used natural pigment of ferrous iron with a cherry-red color consisting of Fe2C > 3 with minor clay and quartz impurities. Surike is 75-95% Fe2 (> 3, ie more than other natural pigments. Also known as red natural pigment mummy containing 20-70% Fe2C > 3 [KopcyHCKHft JI.,., KanHHCKaa TB, CrenHH CH / HeopraHHNeciote ΠΗΓΜβΗΤΒΐ: CnpaBOHHHK CFI6 .: Χημηα, 1992, 336].

Natural iron-containing pigments are obtained by mechanically grinding the minerals containing them, or by enriching and heat-treating iron-containing ores. These pigments are inexpensive but lack color brightness, temperature resistance and good technical coloring properties.

Synthetic iron pigments are produced from iron salts by precipitation or heat treatment. Typically, these pigments do not have the above-mentioned drawbacks [KpacHo6afi H. Γ., JlaTbiuiee K]. B. // SKOHOMHK, τεχΗοποπΜ h opraHH3amm npoH3BOflCTBa acejie3ocoflepMcantHx ΠΗΓΜβΗΤΟΒ: O63op. HmjjopM., ΗΗΗΤ3ΧΗΜ-M., 1991, c. 45], From U.S. patent no. 2057154 (TPK 6 C09C 1/24) A method for producing a brown phosphate-iron oxide pigment, wherein the pigment is precipitated at 90-100 ° C in the form of a sol-gel from a solution of ferric nitrate containing phosphoric acid at a molar ratio of Fe 2C 2 g: 3: P2O5; equal to 1.00: (0.12-0.18) in the presence of urea. It is then filtered, dried and processed at 500-700 ° C. However, after washing and filtering the gel-like product with nitrate ions, the process takes time and expensive ferric nitrate is used.

Patents RU Nr. 2086591 (TPK 6 C09C 1/24) describes a method for obtaining a brown pigment using Marten furnace or blast furnace waste together with calcium hydrogen tetraoxophosphate (CaHPO / O in a ratio of 1: (0.05-0.08) while maintaining the mixture at 60-80 ° C At a temperature of 1.0-2.0 hours at C, then washing the product with water-soluble materials and treating at 150-350 ° C, the disadvantage of which is that a separate apparatus is required to obtain CaHPO4 and reduces the chromophore Fe (III). From patent CN 1310207 (TPK 7, C09 1/24, publ.: http // v3 .espacenet.com / searchResults? locale = lt_LT & AB = red + pigment * + AND + sludge & c .. 23.03.2009 (access via http: //www.vpb.lf) The method of recycling industrial sludge containing more than 38% Fe 2 O 3 is known, when the sludge is treated with sulfuric acid, then washed with water, the precipitate is filtered, oxidized and aged. The precipitate is then washed again and filtered, then heated and milled to give a red pigment which is used for painting ceramic products and high temperature glazes. This method 3 requires a lot of processing steps, consumes a lot of industrial water, which again pollutes the environment, and filtering the small dispersion reduces the efficiency of the method.

Patents RU Nr. 23292204 (TPC 8 C03C 1/04, Publ. 2008, Bulletin No. 20) describes a method for obtaining a brown pigment from a charge having the following composition: chromium oxide 20-30%, zinc oxide 5-10%, red sludge (molar) and bauxite waste containing by weight% silicon dioxide 9.5-11.1; titanium dioxide 4.4-5.6; aluminum oxide 17-19 iron oxide 39-42.9; calcium oxide 7.6 -9.5, sodium oxide 6.2-6.9, kiti 7.8-10.5) 25-36; dolomite 35-40. The above components are ground to pass through the sieve no. 0063, dosed and mixed. The resulting mass is heated at 850-950 ° C in an oxidizing environment. In this process, a large part of the mass is comprised of expensive chromium oxide and a small amount of red sludge consumed.

According to the sludge recycling method closest to the present invention, the sludge recycling method is described in the brown pigment described in B Y No. 3949 (TPK 7 C09C 1/24). The essence of the invention is that the sludge obtained from the purification of wastewater using FFH and containing at least 60% Fe2C > 3 is mixed with 85% phosphoric acid in the ratio Fe2C > 3: P2O5 at 1.00: (0.2-0, 3), then the product is dried and heated at 400-700 ° C. The color of the pigment obtained at this temperature is dark brown and, at 600-700 ° C, reddish brown. Oil absorption - 60-100 g / 100 g linseed oil; Coverage - 8-13 g / m2; color brightness (p) - 12-13%, color purity (P) - 38-44%, dominant wavelength λ -597-598 nm. The disadvantages of this method include the fact that the brown pigments obtained have a limited range of shades, high oil tolerance and low color brightness and color purity, because they are present in the Ni, Cr and Cu compounds at temperatures that may produce products with a dirty brown tint. The object of the present invention is to recycle the sludge obtained from the purification of wastewater using FFH into pigmented materials having a wide range of red-brown hues and high dyeing characteristics.

The objective is achieved by further modifying the sludge obtained by dissolving the soluble zinc salt, in part, by zinc sulphate. Addition of zinc sulphate to a sludge molar ratio of 1: (0.10-0.30) and exposure to temperature gives rise to a crystalline hematite (a Fe 2 O 3) phase and avoids the formation of magemite, magnetite, ferrite, which have a dirty dark brown color. Hematite, depending on its dispersion and crystallinity, has a wide range of red-brown shades. Zinc is present in sludge heat treatment products and has a positive effect on the color characteristics of the pigment material.

Thus, the following advantages of this method can be noted: 1 1. Modifying the sludge soluble zinc salt is purposefully obtained by various red-colored * hues-brown pigmented materials with higher color purity and brightness. 2. The present method increases the possibility of using various chemical compositions containing significant amounts of Ni, Cr, Cu and other heavy metal compounds.

The distinguishing features of the present invention are as follows: 1. Type of modifier - use of soluble zinc salt. 2. The weight ratio of Siamese to soluble zinc salt, calculated as Fe2C > 3: ZnO, is 1.0: (0.10-0.30). 3. Sludge temperature treatment at temperatures of 800-850 ° C.

The distinctive features of the invention are further explained below. 1. Modifier Tin.

Based on experimental data, it appears that sludge containing more zinc compounds than nickel, chromium and copper produces products predominantly containing iron oxides (hematite) and zinc oxide (zinc), which are colored in various shades of red, red and brown. color. This depends on the ratio of the crystalline phases, their dispersion and crystallinity. The ratio of the crystalline phases in the temperature-treated products depends on the initial sludge composition and the amount of modifier used. Therefore, zinc sulphate should be considered as a modifier that structurally modifies pigment materials and which affects the physico-chemical changes occurring during the temperature treatment of sludge and the color characteristics of the resulting materials.

Addition of zinc salt to the sludge has a positive effect on the formation of hematite as the main phase, since the distribution of spinach structures with static two and three charge cations in the octahedral nodes does not occur in this case. From these data it can be stated that the color characteristics of the sludge processing products directly depend on their phase composition, which, in turn, is determined by the presence of the original sludge chemical, partly by the presence of metal compounds and primarily by the presence of zinc. 2. Molar ratio of Fe 2 O 2 ZnO in this.

The chemical composition of the sludge obtained by treating wastewater using FFH can be presented as a mixture of iron oxohydrates with absorbed on their surface by heavy metal compounds. [Ey ^ HnoBCKuc ^., EmeHKO JI.C. Hccjie ^ OBaHHe nponecca h npo ^ yKTOB TepMoo6pa6oTKH NewsMOB, nojiyHeHHbix πρκ ohhctkc ctohhlix boa c noMOiBio φβρροφβρρΗΓΗΑρο3οπ3ΐ //) KypHaji npHKJiajmoit χημηη. 2004. T. 77. Ββιπ. 9. C. 1520-51524], the phase composition of the sludge heat treatment products depends on the zinc, nickel, copper and chromium compounds contained therein. With Fe2C > 3: ZnO = 1: (0.1-0.30), hematite is the predominant hematite with temperature treatment products at 800-850 ° C (Table 1-8). The resulting products have a red-brown color. Reducing the amount of zinc compounds in this zinc oxide to Fe2C > 3: ZnO molar ratio of less than 10.0 produces spinach structures and products with dirty brown shades (Table 8-10). Increasing the amount of zinc compounds in the initial one contributes to the crystalline phases of hematite, zinc, during the heat treatment, and improves the coloring and color characteristics of the pigments formed (Examples 4, 11 and 12 in the table).

Addition of zinc compounds converted to zinc oxide to more than 0.3 mole of Fe 2 in clay (> 3, increased zinc content in the heat treatment products, reduced iron (III) content, resulting in a slight reduction in color purity of iron pigments (Table 11 and Examples 12) 3. Temperature range.

The temperature of the soya treatment has a significant effect on the color of the resulting products. There are a number of chemical, physico-chemical and phase transformations that occur in the process of heat treatment products and their coloring technical characteristics. Sludge heating is accompanied by H2O separation, iron oxide crystallization, ferrites formation. Crystallization of hematite (a Fe2C > 3), which has a red color, causes an increase in the color purity of the resulting products.

According to the experimental data, the slurry heated to 700 ° C has magmatite (γ Fe2C > 3) or magnetite ^ 3 () 4) crystalline phases depending on the nickel, chromium, copper or zinc compounds present therein. The transition of the magemite (γ Fe2C > 3) and magnetite ^ 3 () 4 to hematite (a Fe2C > 3) occurs at 800-850 ° C. Therefore, raising the sludge treatment temperature to 800-850 ° C makes it easier to get red-colored products that have a higher brightness and purity of red. When the sludge is heated to 900 ° C and above, particle sintering, agglomeration occurs, resulting in deterioration of the color and coloring properties of the pigments obtained.

In order to determine the use of the obtained products from heat-treated sludge as inorganic pigments, tests with pigment characteristics such as coating and oil susceptibility were performed. As is known, quantification is quantified as the weight of the pigment in grams required to uniformly coat the surface of 1 m2 of paint (g / m). Coatings of inorganic pigments vary widely, and natural iron 6-containing pigments range from 10 to 90 g / m2, synthetic red 4-7 g / m2 [KopcyHCKHH JI. Aj., KajiHHCKaa T. B., OrenHH C.H. HeopraHunecKMe mirMeHTH: CnpaBOHHHK. CfK): Xhmh, 1992, 336]. It has been found that the coverage of pigments obtained from heat-treated sludge varies within a narrow range: from 11 to 17 g / m 2 (Examples 1-8 in the table) and is at the same level as the prototype.

Oil susceptibility is one of the main indicators of pigment quality. Oil-bearing capacity is the amount of linseed oil in grams needed to melt the pigment powder to convert 100 g of powder into paste (g / 100 g). The indicator for the resulting pigments is 47-56 g / 100 g (Examples 1-8 in the table). This is a slightly higher indicator for red and brown iron-containing natural and synthetic pigments with an oil-bearing capacity of 20-50 g / m2 [KopcyHCKHH JI. Aj., KajiHHCKaa T. B., OrenHH C.H. HeopraHHHecKHe ΠΗΓΜεΗΤΒΐ: CnpaBOHHHK. CII6 .: Χημηκ, 1992,336 c.], But not less than the prototype susceptibility to oil (Examples 13 and 14 in the table). The implementation of the invention is illustrated by the following examples.

Examples.

The initial sludge obtained by treating the wastewater using FFH (heterocoagulating) had the following composition,% by weight: Fe2O3 -7.74; FeO - 0.92; ZnO - 0.28; CuO - 0.25; NiO -0.10; CaO - 0.17; Cr 2 O 3 - 0.19; P205 - 0.08; H20 - 87.7 (the remaining 2.57% consists of water co-ordinated with co-ordinating metals via OH groups). The slurry was added with a molar ratio of phosphoric acid Fe2O3: P2Os to the melt, at a level of 1: 0.2, as described in the prototype, homogenized and left to cent. Subsequently, the phosphorus-containing slurry is additionally accompanied by a modifier, soluble zinc salts, in part, ZnSO 4 · 7 H 2 O. The amount of zinc sulphate added is calculated so that the ratio Fe 2 O 3: ZnO corresponds to 1: (0.1-0.3). The modified sludge is homogenized and left for 5-10 hours and then heated slowly to 800-850 ° C. The finished products are crushed and their chemical, phase and dispersive composition and coloring properties are determined.

Phase composition of the obtained products is determined by Bruker AXS (Germany) diffractometer 08 Advance. Spectrophotometer ΟΦ-18 (Russia) with a source of B radiation was used to determine the color characteristics of pigments.

The coloring properties of the pigments (coating and oil susceptibility) are determined according to standard techniques [KopcyHCKHH JI. Aj., KajiHHCKaa T. B., OrenHH C. H. // HeopraHHecKue πΗΓΜβΗΤΒΐ: CnpaBOHHHK. CI16: Xhmhs, 1992, 336]. 7

Results of experimental studies

Test no. Modification Fe203: Zn 0 molar ratio Processing temperature, ° C Color characteristics Coloring characteristics Color visual characteristic Phase composition P +,% ++ P,% λ, nm Coatings, g / m2 Oil absorption, g / 100 g 1 ZnSO 4 - 7H 2 O 1: 0.10 800 37.5 14.3 603 11 49 red-brown hematite, magnetite 2 ZnSO 4 - 7 H 2 O 1: 0.17 800 40.0 17.0 603 12 47 red-brown hematite, magnetite 3 ZnSO 4 - 7H 2 O 1: 0.25 800 40.5 17.6 603 12 50 red-brown hematite, zinc zinc 4 ZnSO 4 - 7H 2 O 1: 0.30 850 42.0 17.9 603 14 52 red hematite zinc zinc 5 ZnSO 4 - 7H 2 O 1: 0.17 900 39.5 16.7 599 17 50 dark red hematite, iranklinite 6 ZnSO 4 - 7H 2 O 1: 0.25 850 41.5 17.5 602 16 56 red hematite, magnetite 7 ZnS04 -7H20 1: 0.10 850 39.5 15.3 603 13 50 red-brown hematite, magnetite 8 ZnS04-7H20 1: 0.10 900 40.5 17.0 602 16 45 dirty red-brown hematite, iranklinite 9 Without modifier 800 30.0 14.0 605 10 60 dirty dark red hem germ, magemite 10 Without modifier 900 25.5 10.7 605 18 56 dirty dark red hematite, magemite 11 ZnS047H20 1: 0.35 800 40.0 17.0 599 15 50 red hematite, zinc zinc 12 ZnS04-7H20 1 : 0.35 900 38.0 16.5 601 17 53 red hematite, iranklinite 13 Prototype * 400 40.0 13.4 600 13 92 brown hematite, magemite 14 Prototype * 700 44.0 13.0 598 8 60 red- brown hematite, magemite P + color purity; P ++ color purity; * Fe 2 O 3: ZnO molar ratio 1: 0.2.

Claims (1)

DEFINITION 1. The method of processing pigment into the pigment material by iron-containing sludge obtained by the treatment of waste water by means of a heterocoagulant, followed by drying and heat treatment of the sludge, further comprising the use of a soluble zinc salt in a quantity corresponding to this Fe 2 O 3: ZnO molar ratio of 1: (0.1-0.3) mixed with phosphorus-containing slurry is homogenized, dried, heat-treated at 800-850 ° C and receives red and red-brown pigment.