RU2219994C1 - Method to manufacture a filtering material and the filtering material - Google Patents

Abstract

FIELD: technology of manufacture of the filtering material. SUBSTANCE: the invention relates to the technology of manufacture of the filtering material from sedimentary rocks. The method of the filtering material manufacture provides for: calcination of the comminuted raw material, treatment of the received intermediate product with an aqueous solution of salts of iron (II) and copper (II), separation of the fluid and solid phases, drying of a solid phase; at that in the capacity of the raw material they use at least, one of minerals, included in the group containing the sedimentary rocks of the type of dolomitic limestone, dolomitic marbles and. The following minerals: dolomite, magnesite, calcite, their synthetic or natural mixes, containing lime carbonates and a magnesium in amount of no less than 95 mass % . The material manufactured in compliance with the invention contains a mix of carbonates CaCO₃ and MgCO₃ coated with the porous film consisting of magnesia oxides, calcium oxides and iron oxides. Total contents CaCO₃ and MgCO₃ is no less than 95 mass %, the total contents of oxides MgO and CaO is no less than 2 mass %, and the contents of iron oxide FeO - 2-3 mass %. Hardness of the material is 3.5-4.0 by the scale of Mohs, firmness 2.8-2.9 g/cm³, bulk density is 1.20-1.25 g/cm³. EFFECT: the invention ensures high efficiency of the filtering material at purification of water iron, manganese, fluorine, hydrogen sulfide. 8 cl, 2 ex

Description

 The invention relates to a technology for the manufacture of filter material, and more specifically filter material based on sedimentary rocks such as dolomitic limestones, dolomite marbles and minerals: dolomite, magnesite, calcite, their artificial or natural mixtures containing calcium and magnesium carbonates. The material made according to the invention can be used to purify drinking water from a water supply system and freshwater sources.

 In modern conditions, in connection with the catastrophic pollution of the environment, the search for materials that ensure high-quality water purification without creating new environmentally hazardous industries is especially relevant.

 In accordance with the recommendations of the World Health Organization, the concentration of iron in water should not exceed 0.3 mg / l, manganese 0.1 mg / ml, fluorine 0.1 mg / ml, hydrogen sulfide 0.05 mg / l. Similar requirements are laid down in domestic regulatory documents: GOST 2874-82, Sanitary Rules and Norms 2.1.4.559-96, etc.

 Known natural materials used for water purification and meeting the above conditions.

So, glauconite green sand, which is natural sand covered with manganese compounds, is used as a catalyst in the process of removing iron, manganese and hydrogen sulfide. Sand is regenerated using KMnO ₄ (1).

 The MTM material is manganese dioxide and is used to extract iron, manganese and hydrogen sulfide from water. Natural manganese ore is reduced in the same way as glauconite green sand (2).

The BIRM material is a SiO _2- based plastic filtering material, the surface of which is coated with magnesia particles (MgO). BIRM is used as a catalyst for the oxidation of undesirable impurities (3).

Materials known from (1), (2), (3) cannot neutralize H ⁺ ions. Because of this, the latter accumulate in water, and the transition of iron to hydroxide, which is a necessary condition for subsequent filtering, is inhibited.

 Among domestic filtering materials based on natural minerals, it is known, in particular, described in (4), (5), (6).

Thus, the material obtained by introducing powdered dolomite into a clay suspension with subsequent granulation and calcination at 800-880 ^° C is known from (4).

A zeolite-based tuff material is known from (5). A method of obtaining a known material includes grinding zeolite-containing tuff, processing it at room temperature with a solution containing divalent manganese ions and then an alkaline solution containing hydrogen peroxide, and drying at 20-100 ^o C.

A known method of obtaining filter material for water purification from various impurities (6), including processing the feedstock, including containing carbonates and oxides, with an aqueous solution of iron nitrate or chloride, followed by heat treatment at a temperature below 200 ^o C. As a result, granules of the starting material are obtained coated with a film containing iron oxide.

In (7), material (MZhF) based on dolomite mined in the Leningrad region is described. A method of manufacturing a known material includes the following stages:
- grinding and classification of dolomite fractions up to 10 mm to a fraction of 0.3-1.5 mm;
- firing the obtained intermediate in an atmosphere of air at 500-900 ^o C for 1-3 hours;
- air cooling;
- treatment with a solution containing Mn ^{+ 2} ions. concentration of 0.01-0.2 mol / l;
- separation of solid and liquid phases;
- drying of the solid phase at 100-200 ^o C.

Such mechanochemical activation of dolomite leads to the fact that the entire surface of the through pores of the granules of the material is covered with manganese dioxide, which is formed during drying at elevated temperatures (100-200 ^o C). This decision on the number of essential features is closest to the claimed and selected by the authors as a prototype.

The main disadvantage of the prototype is the excess yield of manganese ions in the filtrate with an increase in volumetric load. As evidence of this fact, the following test results of the filter medium MZHF in the quick filter at Zelenogorsk water station can be given:
at a daily flow rate of 2000 m ³ / h for the period from 11/13/2001 to 01/07/2002, the concentration of manganese in purified water increased from 0.04 mg / l to an excess concentration of 0.85 mg / l. Moreover, the excess of the limit value equal to 0.1 mg / l has already occurred on 12/07/2001. At the same time, there was an increase in the concentration of iron from 0.1 mg / l, noted on December 6, 2001, to 0.3 mg / l by January 7, 2002.

 Other disadvantages include the high energy intensity of the known process and, as a consequence, the high cost of the filter material.

 The objective of the invention is to develop an affordable and effective filter material that provides a high degree of purification of water from iron, manganese, fluorine and hydrogen sulfide, and a method for its manufacture while reducing the energy consumption of the process and cheapening the material.

The technical result is achieved due to the fact that in the method of manufacturing a filter material based on a mineral, comprising at least one carbonate and calcium and / or magnesium oxide, including mechanochemical activation of the raw material by sequentially carrying out the following actions:
roasting crushed raw materials,
processing the obtained intermediate with an activator,
separation of liquid and solid phases,
solid phase drying
at least one of the minerals included in the group comprising sedimentary rocks such as dolomitic limestones, dolomite marbles and minerals: dolomite, magnesite, calcite, their artificial or natural mixtures containing calcium and magnesium carbonates in an amount of at least 95 are used as raw materials wt.%, and as an activator use aqueous solutions of iron sulfate FeSO ₄ or Mohr's salt FeSO ₄ • NH ₄ (SO ₄ ) and copper sulfate CuSO ₄ concentration [Fe ⁺² ] = 3-12 g / l and [Cu ⁺² ] = 0.3-1.5 g / l.

The material made according to the invention includes a mixture of carbonates CaCO ₃ and MgCO ₃ coated with a porous film consisting of oxides of magnesium, calcium and iron. The total content of CaCO ₃ and MgCO _{3 is} not less than 95 wt.%, The total content of oxides MgO and CaO is not less than 2 wt.%, And the content of iron oxide FeO is 2-3 wt.%. The hardness of the material is 3.5-4.0 on the Mohs scale, the density is 2.8-2.9 g / cm ³ , the bulk density is 1.20-1.25 g / cm ³ .

 The marked characteristics of the material were obtained using physicochemical methods of analysis - emission spectral analysis, chemical analysis, etc.

 It is preferable to use dolomite, magnesite, calcite, their artificial or natural mixtures containing calcium and magnesium carbonates in an amount of at least 95 wt.% With a ratio of calcium carbonate and magnesium carbonate 1: 1, a fraction defined in the range of 0.5- 5.0 mm.

 To obtain the desired fraction, the raw materials are subjected to grinding on a grinder. It is possible to use finished raw materials of the required fraction, therefore crushing and classification are not mandatory actions when implementing the proposed method.

The resulting mixture is calcined in an atmosphere of air at 650-800 ^o C for 1.0-6.0 hours. After cooling, the resulting product is subjected to processing in the reactor with solutions of salts of Fe ⁺² and Cu ⁺² for 1-6 hours, then the solution separated, and the resulting solid phase is dried at a temperature of not less than 100 ^o C.

To prepare aqueous solutions of Fe ^{+ 2} and Cu ^{+ 2} salts, iron sulfate FeSO ₄ or Mora salt FeSO ₄ • NH ₄ (SO ₄ ) and copper sulfate CuSO _{4 are used} . The concentration of aqueous solutions is [Fe ⁺² ] = 3-12 g / l and [Cu ⁺² ] = 0.3-1.5 g / l.

To further reduce the energy intensity of the process before firing, the crushed raw material is subjected to additional processing, for example, by introducing a NaCl salt (content of 1 wt.%) Or other suitable methods known from the prior art and aimed at activating the surface of the granules to reduce the energy intensity of the subsequent decomposition process on it carbonates when heated. The specified processing allows subsequent firing in the temperature range 450-600 ^o C.

The essence of the invention lies in the fact that in the process of firing and exposure to a catalyst, a macroporous filter material of complex composition with chemically active centers, which are catalysts for the oxidation of Fe ⁺² and Mn ^{+2, is formed} . The presence of calcium and magnesium oxides in the solid phase leads to an increase in the pH of the medium, precipitation of iron and manganese in the form of hydroxides, sorption of trace amounts of fluorine, and purification from hydrogen sulfide to form iron sulfide. The presence of micro amounts of copper in the structure of the sorbent, in addition to accelerating the process, also prevents the emergence of microorganism colonies in the filter medium.

 The resulting filter material is regenerated by backwashing and reused.

 Examples of the method.

 Example 1. Purification of artesian water complex by standard admixtures.

The 1.0-2.5 mm dolomite fraction was calcined at 800 ^{° C.} for 4 hours, cooled, loaded into the reactor, and treated with an aqueous solution of iron sulfate FeSO _{4 at a} concentration of 4.0 g / l of Fe ^{+ 2} and copper sulfate CuSO ₄ concentration by Cu ⁺² 0.5 g / l for 4 hours. The solid phase was separated from the solution and dried at 100-150 ^o C.

The filtering material is a mixture of granules of irregular shape, particle size distribution of the mixture: a fraction of 1-4 mm is not less than 95 wt.%, Brown, brown with individual inclusions of gray, hardness 3.5-4.0 on the Mohs scale. The density of 2.8 g / cm ^{3 the} bulk density of 1.25 g / cm ³ . The total content of CaCO ₃ and MgCO _{3 is} not less than 95 wt.%, The total content of oxides MgO and CaO 3 wt.%, And the content of iron oxide FeO 2 wt.%.

Further, the material obtained in accordance with the conditions of Example 1 was loaded into a sorption column (⌀ 250 mm, H 1100 mm) with a bed height of 0.9 m. Water consumption was 0.2-0.3 m ³ / h. The duration of the cleaning cycle is 1.0 year. The operating mode is periodic with stops for regeneration by backwashing. Volumetric load 5 • 10 ³ m ³ .

Source water was characterized by the following indicators: pH 6.5; turbidity 2.5 mg / l; chromaticity 37 degrees; Fe _total 1.5 mg / l; Fe ^{+ 2} = 0.6 mg / L; Mn ^{+ 2} = 1.1 mg / L; H ₂ S = 0.08 mg / L.

Purified water is characterized by the following indicators: pH 7.1; turbidity 0.2 mg / l; chromaticity 5.5 degrees; Fe ⁺³ <0.1 mg / L; Mn ⁺² <0.01 mg / L; H ₂ S <0.01 mg / L.

 Example 2

The material was obtained under the conditions of Example 1, except that 1 wt.% NaCl salt was added to the mixture before calcination, and calcination was carried out at 500 ^° C. As an activator, aqueous solutions of Mora salt FeSO ₄ • NH ₄ (SO ₄ ) of concentration 4.0 g / l by Fe ⁺² and copper sulfate CuSO ₄ concentrations by Cu ⁺² = 0.5 g / l.

The filtering material is a mixture of granules of irregular shape, particle size distribution of the mixture: a fraction of 1-4 mm is not less than 95 wt.%, Brown, brown with individual inclusions of gray, hardness 3.5-4.0 on the Mohs scale. Density 2.9 g / cm ³ , bulk density 1.2 g / cm ³ . The total content of CaCO ₃ and MgCO _{3 is} not less than 95 wt.%, The total content of oxides MgO and CaO 2 wt.%, And the content of iron oxide FeO 3 wt.%.

The material obtained in the conditions of example 2 was tested in the process of purification of tap water in a sorption column ⌀ 250 mm, N 1100 mm, with a layer height of 0.9 m. Consumption of 0.5 m ³ / h

Source water was characterized by the following indicators: pH 6.5; turbidity 0.4 mg / l; color 30 degrees; Fe _total 0.58 mg / l; Fe ⁺² 0.3 mg / L.

Purified water is characterized by the following indicators: pH 7.0; turbidity 0.2 mg / l; chromaticity 15.0 degrees; Fe ⁺³ <0.1 mg / L.

 From the above data it follows that the granular, chemically active filter medium obtained according to the invention provides the necessary purification of water from iron, manganese, fluorine, hydrogen sulfide, as well as purification in terms of color and turbidity.

Water analyzes were carried out in accordance with the following regulatory documents:
GOST 2874-82 Drinking water. Hygiene requirements and quality control.

 GOST 3351-74 Drinking water. Methods for determining taste, smell, color and turbidity.

 GOST 4011-72 Drinking water. Methods for measuring the mass concentration of total iron.

 GOST 4386-89 Drinking water. Methods for determining the mass concentration of fluorides.

 GOST 4974-72 Drinking water. Methods for determination of manganese content.

The test results of the new filter material allow us to draw the following conclusions:
1. The material has the ability to catalyze the oxidation of iron and bind hydrogen ions.

2. Having catalytic activity and alkalizing effect, it contributes to a much faster oxidation of iron and the formation of Fe (OH) ₃ .

3. Compared with the material, BIRM has a higher oxidation rate of Fe ⁺² .

 4. Can work at low pH values (below 6.8).

5. Purifies water regardless of the form in which iron is located (Fe ⁺² / Fe ⁺³ ).

 6. Removes iron in ultrahigh concentrations (more than 10 mg / l).

 7. Does not accumulate hydrogen sulfide.

 8. Removes manganese.

 The new filter media removes iron from both well and tap water. Simultaneously with the iron, suspended particles and natural organic substances, which give color to water, are removed. An active role in the process of water clarification is played by iron hydroxide in the form of an alluvial layer on the loading surface. Having a spongy structure, iron hydroxide itself is a highly effective sorbent, promotes catalytic oxidation of iron and at the same time, due to the developed surface, absorbs the smallest particles of clay, sand and even humic acids.

 Sources used in compiling the description.

 1. James A. Hunt. A Reference guide for dealers. Water Conditioning & Purification, May 2001, p. 34.

 2. James A. Hunt. A Reference guide for dealers. Water Conditioning & Purification, May 2001, p. 34.

 3. James A. Hunt. A Reference guide for dealers. Water Conditioning & Purification, May 2001, p.32.

 4. RF patent 2077380, B 01 J 2/02, 1997.

 5. A.S. USSR 14915680, B 01 J 2/06.

 6. US 5369072, B01Y20 / 12, 12.17.1992.

 7. RF patent 2162737, B01J 20/02, 20/06, 20/30, V01D 39/02, 2000 - prototype.

Claims (8)

1. A method of manufacturing a filter material, including the activation of a mineral-based feedstock comprising at least one carbonate and calcium and / or magnesium oxide, by sequentially carrying out the following steps: roasting the crushed feedstock, processing the obtained intermediate product with an activator, separation of liquid and solid phases, drying solid phase, characterized in that at least one of the minerals included in the group comprising sedimentary rocks such as dolomitic limestone and dolomite Morov and minerals are dolomite, magnesite, calcite, their synthetic or natural mixtures containing calcium and magnesium carbonates in an amount of not less than 95 wt.%, and as an activator are used aqueous solutions of ferrous sulfate FeSO ₄ salts or Mohr's salt FeSO ₄ · NH ₄ (SO ₄ ) concentration of 3-12 g / l and sulfate CuSO ₄ concentration of 0.3-1.5 g / l. 2. A method of manufacturing a filter material according to claim 1, characterized in that minerals with a ratio of calcium carbonate and magnesium carbonate 1: 1 are used as raw materials. 3. A method of manufacturing a filter material according to claim 1 or 2, characterized in that the raw materials of a fraction of 0.5-5.0 mm are used. 4. A method of manufacturing a filter material according to any one of claims 1 to 3, characterized in that before firing the raw materials are subjected to additional processing aimed at activating the surface of the particles of raw materials. 5. A method of manufacturing a filter material according to claim 4, characterized in that the processing of raw materials is carried out by introducing sodium chloride in an amount of 1-5 wt.% Under normal conditions. 6. A method of manufacturing a filter material according to claim 5, characterized in that the firing is carried out at 450-600 ° C for 1-6 hours 7. Filter material made according to any one of claims 1 to 6, comprising granules of at least one carbonate and calcium and / or magnesium oxide, characterized in that it contains a mixture of calcium and magnesium carbonates coated with a porous film consisting of magnesium oxides , calcium and iron, while the total content of calcium and magnesium carbonates is not less than 95 wt.%, the total content of magnesium and calcium oxides is not less than 2 wt.%, and the content of iron oxide is 2-3 wt.%. 8. The filter material according to claim 7, characterized in that its hardness is 3.5-4.0 on the Mohs scale, density 2.8–2.9 g / cm ³ , bulk density 1.2–1.25 g / cm ³ .