RU2462425C1 - Method of processing burnt rock to produce concrete mix filler and concrete mix with said filler - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method comprises the following steps. Burnt rock is crushed to size not exceeding 50 mm. Crushed burnt rock is sieved at 20 mm-mesh screen. Crushed burned rock that passed through screen is rejected. Crushed burnt rock remained on screen is crushed again to sieve it at screens with smaller meshes and to separate it into sand and gravel fractions. Said sand and gravel fractions are placed into separate bins. Said fractions are fed into concrete mixer as concrete fillers.

EFFECT: invention facilitates reducing content of bad compounds and organic impurities, optimised composition.

10 cl, 2 tbl

Description

The invention relates to the production of building materials, namely the production of concrete mixtures based on aggregates from waste from the coal industry, used for the manufacture of artificial stones.

A known method of manufacturing building blocks from concrete mix containing Portland cement and aggregate from gravel, pebbles and sand obtained from the processing of household waste, waste glass, chemical, smelting and waste from the development of underground mines and quarries, including shale and burnt clay breed [patent GB 190207647, publ. 03/05/1903]. The dried initial components of the aggregate are mixed with each other, crushed in a crushing machine to obtain granules of the desired size and sieved through a sieve. Part of the waste passing through the sieve is used as a filler for the concrete mixture, to which Portland cement is added in an amount of 5-10% of its weight. The resulting mixture is mixed in a concrete mixer with the addition of water and a hydraulic additive in the form of lime paste and adjusted to the desired consistency by adding alkaline silicate. The disadvantages of the known concrete mixture are: the heterogeneous composition of the aggregate, consisting of components that are different in nature by their origin and have different chemical and mineralogical characteristics, which negatively affects the physical and mechanical properties of the concrete mixture and consumer properties of building products obtained from it, the complexity of the manufacturing process mixtures and the limited scope of its application due to the insufficiently wide range of systems produced on its basis Yelnia articles having low strength raw lack an optimized ratios of fractions in the filling, which leads to an increase in the voids between the particles of aggregate and cement paste overrun in the manufacture of concrete, its difficulty in regulating the operating characteristics during fabrication.

A known method of processing burned rock accumulated in mine dumps and using it as a lightweight aggregate for concrete mixtures intended for the manufacture of wall products [patent PL 275856, publ. 05/28/1990]. According to the method, the waste burnt rock with a particle size of 0-50 mm is moved with a bulldozer to the receiving hopper, from where it is fed to a mechanical vibrating screen through a conveyor belt, where it is divided into fractions. About 15% wt. Are sieved through a sieve. burnt rock with a fraction of less than 16 mm, which is used as aggregate for the concrete mixture, and the burnt rock remaining on the sieve with a grain size of 16 to 50 mm is used as a semi-finished product for the production of hydraulic additives to Portland cement used to prepare the concrete mixture. The disadvantages of this method are: a relatively small yield of aggregate and its low quality; the impossibility of optimizing the required ratio of fractions in the aggregate, which leads to an increase in the voids between the particles of the fractions and the cost overrun of cement dough in the manufacture of concrete mix; the need for additional adjustment of the chemical and mineralogical structure of the aggregate to ensure the required physical and chemical properties of the concrete mixture in its manufacture.

Known concrete mixture for the manufacture of building products, including a binder in the form of Portland cement (6-12 wt.%), Large aggregate in the form of dump metallurgical slag (35-40 wt.%) And burnt rock heap (35-40 wt.%), and also a fine aggregate in the form of fly ash (4-6 wt.%), and a hardener in the form of water [patent RU 2288199, publ. 02/10/2006]. The disadvantages of the known mixture are the heterogeneous composition of the aggregate, consisting of components that are different in nature of origin and have different chemical and mineralogical characteristics, which negatively affects the physical and mechanical properties of the concrete mixture and consumer properties of building products obtained from it, in addition to slag, burnt rock and ash, which are part of the aggregate, contain sulfur compounds, which are classified as harmful impurities in the concrete mix, a large amount of neighing in the aggregate of metallurgical slag, which has large pores, which reduces the structural and strength characteristics of the concrete mixture and increases the cost of cement dough, and the use of fly ash as a sand filler slows down the setting and increase of the initial strength of the concrete mixture and increases its shrinkage during curing, therefore it is necessary adjustment of the chemical and mineralogical compositions of the components that make up the filler by adding a large number of corrective and stabilizing suitable additives, which complicates the technology and increasing labor and energy costs to produce it.

The technology of processing burnt rock from the waste heap in the area of the village of Yuryevka in the Donetsk region (Ukraine), which is used as a filler corresponding to the brand 1000-1100 for concrete mix intended for the manufacture of wall blocks, was selected as a prototype [Ryazanov AN, Krytsya P.E. Physico-mechanical properties and technology of rock-concrete / Scientific Bulletin of LNAU: - Lugansk, 2009, No. 2, pp. 3-8]. The initial burnt rock is fed into the receiving hopper with a bulldozer, on the upper part of which a welded grate with cells of 120 × 120 mm in size is installed. The rock of fractions 0-120 mm is sieved through the cells of the grate and the hopper is filled, while pieces larger than 120 mm remaining on the surface of the grate are manually removed. The rock is fed from the hopper by a plate conveyor to an inertial screen, where metal inclusions are removed from it by means of a magnetic catcher along the transportation path. The screen is equipped with two screens, where the upper sieve is equipped with 20 × 20 mm cells, and the lower sieve is equipped with 4 × 4 mm cells. The rock is sieved through sieves, where pieces larger than 20 mm remain on the upper sieve, and fractions of 4-20 mm remain on the lower sieve, while the screening of fractions 0-4 mm passed through the lower sieve is removed by a conveyor belt to the dump, since screening contains a large number of sulfur compounds and organic impurities that impair the quality of the concrete mixture. Pieces of rock larger than 20 mm are conveyed by a belt conveyor to a hammer mill, in which they are crushed to a particle size of not more than 5 mm, after which a belt conveyor is fed into a feed hopper located above the concrete mixer. There, bypassing the crusher, a conveyor belt serves the fraction of 4-20 mm from the lower sieve of the screen. From a feed hopper equipped with a feeder and a weighing batcher, a filler of fractions of 0-20 mm is fed into a concrete mixer installed above the molding unit. In the manufacture of the concrete mixture, Portland cement is supplied in the required quantity to the concrete mixer from the silo with a screw according to the timing. After mixing the dry components, the volumetric water is dispensed into the concrete mixer. Stirring is resumed and produced until a concrete mixture of uniform humidity is obtained without lumpy inclusions of raw materials. From the concrete mixer, the finished mixture is fed into the feed hopper of the vibroforming unit, which is equipped with a four-block lifting form with a vibrator, a sliding trolley with a removable pallet and a pneumatic load. The disadvantages of the known method of processing burned rock to obtain aggregate for concrete mix are: a low degree of purification of the aggregate, which determines its high degree of contamination with harmful sulfur compounds and organic impurities contained in the feedstock, due to their incomplete screening during crushing and sieving of burned rock, as pieces of rock with impurities and impurities larger than the screening of fractions 0-4 mm, remain in the rock, which is directly used as aggregate for concrete impurity, which reduces the quality of the mixture, and the lack of optimization of the crushed stone fractions filler leads to an increase in voids in the concrete mixture of cement paste and overrun.

An object of the present invention is to provide aggregate for lightweight concrete mixtures from recycled burned rock having a relatively low content of harmful compounds and organic impurities and to optimize the composition of concrete mixtures for molding building products with desired physicomechanical and thermotechnical properties, as well as reducing the consumption of cement paste in the preparation of concrete mix.

To solve the technical problem, a method for processing burnt rock is proposed, including crushing the rock, screening foreign impurities and separating it into sand and gravel fractions, which are used as aggregate for concrete mix. New is that they use the following process: initially, the rock is crushed to a particle size of not more than 50 mm; crushed burnt rock is sieved through a No. 20 sieve with 20 mm mesh; discard the crushed burned rock passed through a No. 20 sieve; re-crushed the crushed burnt rock remaining on sieve No. 20 larger than 20 mm and sieved through sieves with smaller cells with separation into sand and gravel fractions; sand and gravel fractions of the re-crushed burned rock are placed in separate storage bins; sand and / or crushed stone fractions, placed in separate storage bins, are fed into the concrete mixer as a concrete aggregate in an effective amount.

Discarded crushed burned rock can be used as a material for filling roads, due to which it is possible to achieve complete utilization of burned rock.

When re-crushing and sieving, crushed burned rock larger than 20 mm is better divided into fractions of 0-5 mm; 5-10 mm and 10-20 mm.

A fraction of 0-5 mm can be divided into two or more sand fractions by sieving on sieves, for example, to obtain sand fractions of 0-0.14 mm; 0.14-0.315 mm; 0.315-0.63 mm; 0.63-1.25 mm; 1.25-2.5 mm and 2.5-5.0 mm.

As aggregate in the form of crushed stone, it is better to use crushed stone fractions of 5-10 mm and 10-20 mm at their ratio,% wt .: 40-60: 60:40.

In the method can be used burned waste coal mine coal.

Also proposed is a concrete mixture containing Portland cement, aggregate in the form of crushed stone and / or sand fractions of crushed burned rock obtained by the claimed method, and water in effective amounts.

Crushed stone and / or sand fractions of crushed burnt rock can have the following chemical and mineralogical composition,% wt .: SiO ₂ - 71.10; Al ₂ O ₃ - 17.45; Fe ₂ O ₃ - 3.66; TiO ₂ 0.64; CaO - 1.22; MgO - 0.64; SO ₃ - 0.03; K ₂ O - 2.62; Na ₂ O - 1.27.

For the manufacture of most concrete products, a concrete mixture with a flow rate of 1 m ³ can be used: Portland cement - 167-256 kg; sand fractions of crushed burned rock - 683-508 kg; crushed stone fractions of crushed burned rock - 683-798 kg; and water - 315-300 kg.

With a further more detailed description of the present invention, Table 1 with the main characteristics of the compositions of the optimal ratios of crushed stone fractions and Table 2 with the characteristics of the optimal compositions of the concrete mix according to the embodiments of the present invention are used.

The present invention is illustrated by examples of technology for processing burnt rock concentrated on the heaps of coal mines in the town of Artema, Primorsky Territory, with the further use of recycled burnt rock as a filler for concrete mix intended for the manufacture of wall blocks and other typical concrete products.

The burnt rock of the coal mine heaps is developed by a bulldozer and fed to the receiving hopper by an excavator, from where it is conveyed to the jaw crusher, where primary crushing of the rock to a particle size of not more than 50 mm is carried out.

Next, crushed burned rock with a particle size of 0-50 mm is fed to a two-sieve vibrating screen, where it is sieved through a sieve with a mesh size of 20 mm and foreign impurities are discarded (usually about 25 ± 5% of the initial amount of burned rock) in the form of dust and a contaminated fraction the size of 0-20 mm, containing wood, clay particles and unburned coal. In the future, such discarded impurities can be used as material for adding roads.

The crushed burned rock remaining on the sieve with a grain size of 20-50 mm (usually about 75 ± 5% wt. Of the initial amount of burned rock), which is sufficiently homogeneous in chemical and mineralogical composition and suitable for use as a filler, is crushed again on a roller crusher, fed through a feeder to a two-sieve inertial screen, where they are sieved and divided into fractions of 0-5 mm, 5-10 mm and 10-20 mm in size.

The following chemical and mineralogical composition of crushed burnt rock, suitable for use as a filler,% wt .: SiO ₂ - 71.10; Al ₂ O ₃ - 17.45; Fe ₂ O ₃ - 3.66; TiO ₂ 0.64; CaO - 1.22; MgO - 0.64; SO ₃ - 0.03; K ₂ O - 2.62; Na ₂ O - 1.27.

Further, the 0-5 mm fraction is additionally sieved on fine-mesh sieves with the separation of this fraction into smaller sand fractions of 2.5 mm, 1.25 mm, 0.63 mm, 0.315 mm and 0.14 mm in size. Usually received the following number of such sand fractions, in the form of total residues on the corresponding sieves,% wt .: No. 2.5 - 25.5; No. 1.25 - 40.0; No. 0.63 - 54.0; No. 0.315 - 67.5; and No. 0.14 - 80.5, where through a sieve No. 0.14 passed 19.5% wt.

The resulting sand fractions belong to the sand of the middle group with a particle size modulus of 2.68 and bulk density γ _n = 1050 kg / m ³ . By granulometric composition and bulk density, such sand corresponds to grade 1100 and is suitable for use as a light fine aggregate for concrete mix.

Crushed stone and sand fractions are separately accumulated in separate storage and storage bins of the section for molding wall blocks of concrete using various fractions or combinations of fractions as a filler. Fractions are stored in an amount sufficient for the smooth operation of the site during the week.

Use storage bins equipped with dispensers, with which, based on previously obtained laboratory data, the ratio of aggregate fractions is optimized before being fed to the concrete mixer.

The optimal ratios of gravel fractions of 5-10 mm and 10-20 mm were determined in the aggregate with the following proportions by weight: 40/60, 50/50 and 60/40. The main characteristics of the indicated ratios of crushed stone fractions are presented in Table 1. In terms of bulk density, such crushed stone fractions correspond to gravel of grade 900, which characterizes it as a lightweight coarse aggregate for concrete mix.

In addition to the storage and storage bins for sand and gravel fractions, the section for forming wall blocks is equipped with a storage and storage bunker for Portland cement and a technological water reserve tank. Each hopper is closed to a concrete mixer connected by a technological line to a VIP-10-type forming complex, which includes a vibrating press, a heat treatment chamber and a finished goods warehouse, interconnected by concrete and pallet feeding mechanisms.

In a concrete mixer, the metered initial components of the concrete mixture are mixed in the form of Portland cement, crushed stone and sand in the form of crushed stone and sand fractions from crushed rock and water. Wall blocks are made of ready-mixed concrete by vibropressing. At the end of molding, pallets with freshly formed products are served on trolleys in a steaming chamber, where they are subjected to heat and humidity treatment at a temperature of t = 80-90 ° C for about 8 hours.

After heat-moisture treatment of products (TVO), the trolley is unloaded with a stacker-manipulator and pallets with finished products are transferred to the feeding mechanism for subsequent separation of products from pallets and feeding them under the manipulator for containerization. Finished products are transported on special multi-turn flat pallets or in packages to an indoor warehouse for storage of finished products.

For the manufacture of most concrete products, in particular the above wall blocks, a concrete mixture can be used with a flow rate of 1 m ^{3 the} following number of source components, kg: Portland cement - 167-256; sand fractions of crushed burned rock - 683-508; crushed stone fractions of crushed burned rock - 683-798 g; and water - 315-300. Such a concrete mixture can be used for molding building products with the required physicomechanical and thermotechnical characteristics, which depend on the ratio of the initial components of the concrete mixture, the optimal compositions of which are presented in table 2.

The data regarding the compositions presented in table 2 allow us to conclude that the resulting concrete mix belongs to the group of structural and heat-insulating concrete, where blocks of class 3.5 can be used to produce blocks for the laying of heat-insulating and sound-insulating layers of building walls, from concrete mixes of class B 5.0, it is possible to produce blocks for laying the internal partitions of the building, and from concrete mixes of class 7.5 it is possible to produce blocks for laying the external walls of the building. With a density of γ _b = 1650 kg / m ³ in a dry state and compressive strength after 28 days, R _cr = 10.2 MPa of a concrete mix of class B 7.5, intended for the manufacture of blocks for laying the exterior walls of a building, its thermal conductivity is λ _b = 0.680 W / m ° C, which corresponds to the thermal conductivity of the concrete mixture on the aggregate of granulated blast furnace slag.

It should be understood that the above examples are used only to illustrate particular cases of carrying out the invention and such examples do not limit the scope of legal protection presented in the attached claims, while a specialist in the art is relatively simple able to implement other embodiments of the present invention in the framework of of this formula.

Table 1 Properties of optimal ratios of crushed stone fractions The ratio of crushed stone fractions in the aggregate,% wt .: 40/60 50/50 60/40 Water absorption,% 18.5 16.5 18.5 Bulk density, kg / m ³ 880 895 880 Porosity,% 43.5 41.0 43.0 The average density of the mixture of crushed stone fractions in the cement paste, kg / l - 2.22 -

Claims (10)

1. A method of processing burned rock, including crushing the rock, screening out impurities and separating it into sand and gravel fractions, which are used as aggregate for the concrete mix, characterized in that the following process is used:
initially, the rock is crushed to a particle size of not more than 50 mm;
crushed burnt rock is sieved through a sieve with 20 mm mesh;
discard the crushed burnt rock passing through the sieve;
re-crushed the crushed burnt rock remaining on the sieve larger than 20 mm and sieved through sieves with smaller cells with separation into sand and gravel fractions;
sand and gravel fractions of re-crushed burned rock are placed in separate storage bins;
sand and / or crushed stone fractions, placed in separate storage bins, are fed into the concrete mixer as a concrete aggregate aggregate. 2. The method according to claim 1, characterized in that the discarded crushed burnt rock is used as a material for adding roads. 3. The method according to claim 1, characterized in that when re-crushing and sieving the crushed burned rock larger than 20 mm is divided into fractions 0-5 mm; 5-10 mm and 10-20 mm. 4. The method according to claim 3, characterized in that the 0-5 mm fraction is divided into two or more sand fractions by sieving on sieves. 5. The method according to claim 4, characterized in that when sifting on sieves, sand fractions of 0-0.14 mm are obtained; 0.14-0.315 mm; 0.315-0.63 mm; 0.63-1.25 mm; 1.25-2.5 mm and 2.5-5.0 mm. 6. The method according to claim 6, characterized in that gravel fractions of 5-10 mm and 10-20 mm are used as aggregate at their ratio, wt.%: 40-60: 60:40. 7. The method according to claim 1, characterized in that they use the burnt rock heap of the coal mine. 8. Concrete mixture containing Portland cement, aggregate in the form of crushed stone and / or sand fractions of crushed burned rock and water, characterized in that it contains aggregate obtained by the method according to any one of claims 1 to 6. 9. The mixture according to claim 8, characterized in that the crushed stone and / or sand fractions of the crushed burned rock have the following chemical and mineralogical composition, wt.%: SiO ₂ - 71.10; Al ₂ O ₃ - 17.45; Fe ₂ O ₃ - 3.66; TiO ₂ 0.64; CaO - 1.22; MgO - 0.64; SO ₃ - 0.03; K ₂ O - 2.62; Na ₂ O - 1.27. 10. The mixture according to claim 8, characterized in that the flow rate per 1 m ³ is, kg: Portland cement - 167-256; sand fractions of crushed burned rock - 683-508; crushed stone fractions of crushed burned rock - 683-798; and water - 315-300.