RU2100615C1 - Mixture for filling of worked-out space - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: mixture contains fired carbonate rocks, filler, water and added with sulfate-containing rocks, plasticizer and active alumosilicate rocks. EFFECT: higher efficiency. 2 dwg, 1 tbl

Description

 The invention relates to the mining industry and can be used for the construction of artificial arrays in the development of deposits by underground mining.

 A known mixture for laying open space, including wt.

Cannon Lime 5 8
Ground clay, calcined at 650,700 ^o C 10 16
Tailings 76 85
(ed. St. N 655678, class C 04 B 15/08, 1979)
A disadvantage of the known technical solution is the high cost due to the use of natural materials (lime, clay), the extraction of which requires the construction and maintenance of quarries and quarries and low strength at low temperatures, since this mixture does not self-heat during hardening (in lime - all CaO is converted to Ca (OH) ₂ , which does not have heat emission). Mixtures on lime-cannon at temperatures below 10 ^o C do not harden.

 The closest in technical essence and the achieved result is (Mixture for laying open space, ed. St. N 1677340, class E 21 F 15/00, 1991). The mixture contains the following components, wt.

Ground overburden carbonate rocks calcined at 1200 1300 ^o C - 9.0 25.2
Placeholder 51.1 76.0
Water Else
The disadvantage of this composition is the low operational properties of the mixture inherent in all mixtures on cements: short setting time, water separation and shrinkage deformation of the freshly laid massif and low early strength. In addition, the complex technology of binder production, which is practically no different from the production of Portland cement, determines its high cost.

 The aim of the invention is to improve the operational properties of the mixture while reducing its cost. This goal is achieved in that the mixture for laying the mined-out space, containing calcined carbonate rocks, aggregate and water, additionally contains sulfate-containing rocks, a plasticizing additive and active aluminosilicate rocks in the following ratio of components, wt.

Carbonate rocks calcined at 900 1150 ^o C 3.5 13.2
Active aluminosilicate rocks 3.0 16.5
Sulphate-containing rocks 0.4 1.5
Plasticizing additive 0.02 0.4
Placeholder 32 68.4
Water Else
Stowing mixtures should be characterized by certain properties: transported through pipes in a gravity-free mode without separation and water separation, spread out in the worked-out space at an angle of not more than 6 ^o , set for 2 to 12 hours, gain strength of 0.5 to 10 MPa in contact with permafrost, have mobility 11-14 cm, ultimate shear stress less than 200 Pa.

Carbonate rocks are a waste of diamond mining quarries, as they compose the host rocks of kimberlite pipes. Carbonate rocks are stored in a special dump and are characterized by the following chemical composition, wt. (averaged sample) CaO 41.70; MgO 15.90; SiO ₂ 0.10; Al ₂ O ₃ 0.90; Fe ₂ O ₃ 0.20; SO ₃ 0.42; p.p.p. 40.40.

Firing of carbonate rocks is carried out at a temperature of 900 1150 ^o C with the aim of the most complete decarbonization. At temperatures below 900 ^o C the decarbonization process does not occur, and at temperatures above 1150 ^o C may burn out and the transition of active MgO to periclase.

Calcined overburden carbonate rocks include the following oxides, wt. CaO 56 70; MgO 15 34; SiO ₂ 0.1 0.3. The content of active CaO 45 65% and active MgO 14 32%
The rational area for introducing calcined carbonate rocks into the composition of the filling mixture is 3.5 13.2%. When the content of calcined carbonate rocks is below the declared limit, self-heating of the filling mixtures in the worked out space does not occur (composition 13). The introduction of calcined carbonate rocks above the claimed limit leads to a deterioration in the rheological parameters of the mixture (composition 4), the mixture quickly thickens, loses mobility, the ultimate shear stress exceeds the permissible value (τ> 200 Pa).

Active aluminosilicate rocks contain silica and alumina in active form. Active aluminosilicate rocks can already be naturally active materials such as zeolite rocks or tuffs. However, it is possible to use naturally inert materials with an aluminosilicate composition, during the heat treatment of which silica and alumina become active, for example, aluminosilicate rocks burnt at 750 850 ^o C overburden of one of their quarries in the diamond mining industry.

The chemical composition of the zeolite rocks of the Honguruu deposit contains the following basic oxides, wt. SiO ₂ 66 68; Al ₂ O ₃ 10 12; CaO 2 -4; MgO 1 2; (K ₂ O + Na ₂ O) 3 4. The content of soluble alumina 7 10% active silica 2 3%
The following basic oxides, wt. SiO ₂ 40 55; Al ₂ O ₃ 6 16; CaO 2 7; MgO 4 7; soluble alumina content 6 16% and active silica 0.4 4.5%
The mineralogical composition of zeolite rocks includes 75 95% clinoptilolite and 5 25% quartz, feldspars, fragments of siliceous rocks, volcanic glass, biotite, clay and other minerals. Zeolite rocks are characterized by the stability of their composition.

 Tuff rocks are represented by a lithocrystalline, crystalloclastic, and vitrocrystalline plastic structure. They consist of fragments of lava and sedimentary rocks, often cemented with chlorite-serpentine mixed with oxides and hydroxides of iron, minerals of the leucite group and sometimes zeolites. Clastic material is represented by quartz, feldspar, porphyry microdolerites and vitrophyric base, microquartzites and volcanic glass. Feldspar is often altered and replaced by clay material (illite, montmorillonite). In the mass of altered glass, the development of chlorite, serpentine, talc, mica, calcite and iron hydroxides is observed.

Silica particles contained in aluminosilicate rocks interact with Ca (OH) ₂ to form CSH (B).

At the same time, active alumina interacts with calcium oxide hydrate to form metastable hexogonal dicalcium and tetracalcium hydroaluminates or mixtures thereof, which over time slowly transform into stable 3CaO • Al ₂ O ₃ • 6H ₂ O.

The presence of active alumina and silica also causes the formation of gelenite hydrate and 3CaO • Al ₂ O ₃ • 4SiO ₂ hydrogranates
Aluminosilicate inactive rocks are also a waste product - overburden rocks. The average sample of inactive aluminosilicate rocks is characterized by the following chemical composition, wt. SiO ₂ 35.04; Al ₂ O ₃ 9.71; Fe ₂ O ₃ 4.71; CaO 17.71; MgO 4.14; SO _3, 9.65; K ₂ O 3,17; Na ₂ O; pp 15.29.

 Thermal analysis of inactive aluminosilicate rocks established the rational temperature of their firing (figure 1).

Это соединение в водной щелочной среде легко распадается на ионы Al(OH)²⁺ и SiO $\genfrac{}{}{0ex}{}{\text{2-}}{\text{3}}$ и является показателем высокой реакционной активности материала к CaO и MgO, содержащихся в обожженных карбонатных породах:

Алюмосиликатные породы играют важную роль и в обеспечении требуемых реологтческих показателей смеси. Тонкодисперсные частички активных алюмосиликатных пород, адсорбционно удерживая на своей поверхности значительное количество воды, создают своеобразную смазку для всех составляющих закладки, уменьшая трение между ними. Одновременно адсорбированная вода выполняет роль смазки между закладочной смесью и стенкой трубопровода. Возникает тиксотропный эффект, снижающий коэффициент пристенного трения и увеличивающий растекаемость смеси в выработанном пространстве. Адсорбционно вода удерживается до прекращения транспортирования смеси и начала реакции с частичками окисей кальция и магния.On the thermogram, the first negative (endothermic) effect corresponds to a temperature of 150 180 ^o C. At a temperature of 570 590 ^o C, the first hydrated water molecule is removed. At a temperature of 700 - 850 ^o C, the second molecule of hydrated water is removed, while silica and alumina become active:

This compound in an aqueous alkaline medium easily decomposes into Al (OH) ²⁺ and SiO ^ions $\genfrac{}{}{0ex}{}{\text{2-}}{\text{3}}$ and is an indicator of the high reactivity of the material to CaO and MgO contained in calcined carbonate rocks:

Aluminosilicate rocks play an important role in ensuring the required rheological characteristics of the mixture. Fine particles of active aluminosilicate rocks, adsorbingly holding a significant amount of water on their surface, create a kind of lubricant for all the components of the bookmark, reducing friction between them. At the same time, adsorbed water acts as a lubricant between the filling mixture and the pipe wall. A thixotropic effect occurs, which reduces the coefficient of wall friction and increases the spreadability of the mixture in the worked out space. Adsorption water is retained until the transportation of the mixture ceases and the reaction begins with particles of calcium and magnesium oxides.

 The rational area of introduction of active aluminosilicate rocks is 3 16.5%. When their content is lower than the declared limit, the strength of the bookmark decreases, since there are not enough reactive ions contained in aluminosilicate rocks to form the above-mentioned minerals (composition N 1). Exceeding this limit is impractical due to the fact that the specified strength has already been achieved and there is no need to overspending the expensive component of the bookmark (composition No. 4).

Sulphate-containing rocks are also represented by production waste - overburden rock of one of the quarries. The average sample of rocks includes the following basic oxides wt. CaO 31.03; SO ₃ 44.62; SiO ₂ 2.55; Al ₂ O ₃ 0.37; p.p.p. 20.53.

Sulfate-containing rocks play two roles in the filling mixture. Firstly, they slow down the hydration reaction of CaO and MgO, which makes it possible to transfer the heat release process to mine workings. Secondly, calcium sulfate reacts with the products of reactions (2) and (3), forming the necessary amount of ettringite Ca ₆ Al ₂ (SO ₄ ) ₃ (OH) ₂ • 26H ₂ O in the initial stages of hardening, which increases the strength of the bookmark.

 Sulphate-containing rocks should be contained in the mixture within 0.4 to 1.5% by weight of the bookmark. When introduced below the claimed limit, the required bookmark strength and the required heat release rate (composition N 6) are not achieved. An overdose of sulfate-containing rocks is impractical, since it does not improve the already achieved technological parameters of the bookmark (composition N 5).

 As plasticizing additives can be used any plasticizers, for example: LST technical modified lignosulfates, OST 13-183-83; C-3 superplasticizers are the product of the polycondensation of naphthalenesulfonic acid and formaldehyde, or a combination thereof. When a dispersing phase is added to the binder, a film is formed on the surface of the particles of the particles, which provides a thinning effect upon mixing of the mixture that affects the properties of the mixture: the ultimate shear stress and the spreading angle of the mixture in the worked out space are reduced. In addition, the claimed dosage of plasticizer provides a given duration of heat generation of the bookmark, which ensures self-heating of the bookmark in the worked out space, and not in the pipeline.

 In FIG. 1 is a graph of firing temperature of aluminosilicate rocks; in FIG. 2 is the heat release rate of calcined carbonate rocks and filling mixtures based on them, where 1 calcined carbonate rocks, 2 filling mixture, 3 filling mixture containing S-3 superplasticizer based on sodium salts of the product of condensation of naphthalene sulfonic acid with formaldehyde.

 The plasticizer is introduced into the mixture either in the process of grinding the binder, or directly into the concrete mixer with mixing water. Its optimum amount is 0.02 0.4% by weight of the bookmark. With a smaller amount of plasticizer, the required properties of filling mixtures (composition No. 9) are not achieved. Excess plasticizer reduces the strength of the bookmark (composition 15).

 The amount of water in the filling mixture is determined from the requirement of the required bookmark mobility of 14 cm by immersion of the reference cone. This factor is fundamental to ensure the transportability of the mixture through the pipes.

 Any cost-effective materials can serve as filler of filling mixtures: fine-grained sands, crushed rocks, tailings.

 A method of manufacturing a filling mixture includes the following stages.

 Carbonate, aluminosilicate and sulfate-bearing rocks are crushed and screened. Carbonate rocks of -100 + 40 mm fraction are fired in a shaft furnace. Sulphate-containing rocks of -40 + 0 mm class are sent to silos in front of the mill. Aluminosilicate rocks are burned if necessary in a rotary kiln. Active breeds also enter the bunkers in front of the mill. Dosage materials are ground in a mill. In order to ensure the specified heat of hydration of the ground product (60,150 cal / g), the material is sprayed with water if necessary during grinding, then it is mixed with aggregate, plasticizer and water and fed into the worked-out space through pipes. In the workings, the mixture self-heats up and hardens.

 The test results of the mixture are given in the table.

The production of filling mixtures of the proposed composition does not require significant investments in construction, since most of the limits are located in unheated buildings. The absence of the need to obtain a predetermined composition before firing the raw material mixture eliminates such energy-intensive processes as grinding the material before firing and averaging its composition in horizontal and vertical slurry basins. In addition, the firing is not wet, as in the prototype, but dry material, and part of the material is either not fired or fired at a temperature lower than the prototype (700 850 ^o C), which significantly reduces the energy consumption of the process.

Claims (1)

 A mixture for laying a mined space containing calcined carbonate rocks, aggregate and water, characterized in that it additionally contains sulfate-containing rocks, a plasticizing additive and active aluminosilicate rocks in the following ratio of components, wt. Carbonate rocks calcined at 900 1150 ^o С 3.5 13.2
Active aluminosilicate rocks 3.0 16.5
Sulphate-containing rocks 0.4 1.5
Plasticizing additive 0.02 0.4
Placeholder 32.0 67.0
Water Else

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