DE102016117084B4 - Use of an injection agent - Google Patents

Abstract

Use of an injection agent (3), comprising at least:
silicic acid-containing solution and an alkaline activated binder system comprising at least granulated slag and / or metakaolin and / or silica fume, wherein the injection medium (3) is free of organic components for filling, solidifying and sealing pathways (1a, 1b) in a natural or artificial rock (2) or a mining offset in a mine.

Description

The invention relates to an injection agent for filling, solidifying and sealing pathways in rocks or mining offsets.

Pathways in rocks, natural as well as artificial (eg concretes) or mining offsets can be in the form of cavities of different sizes, such as clefts, cracks or pore systems. These pathways cause solutions stored in rocks or mining offsets, such as waters, to penetrate into mined cavities. In addition, the cavities can lead to instability of the rock or the mining offset. In order to avoid this, injections are provided with which the cavities are filled in order to seal them and to stabilize or seal the rock or the mining offset.

For injection of larger cavities particle-based injection means are provided. Particle-based injectors for larger cavities here are cementitious suspensions that can be prepared with water and / or a sodium chloride solution or suspensions based on magnesium oxide and / or magnesium hydroxide, which are mixed with a magnesium chloride solution.

To fill, consolidate and seal a system with cracks and / or pores of different sizes, several single injections with different injectables are necessary. In a first step, larger cavities are injected with the coarser, particle-supported injection means. With decreasing size, the cracks or pores are first compressed with fine-particle, particle-supported injection means and then with particle-free injection means.

The disadvantage here is that cements and Feinstzemente, i. the binders of suspensions and particle-based injectables, are highly hygroscopic. This greatly reduces their shelf life. As a result of the reaction with moisture, including the air, they lose their ability to react with the mixing water of the suspension or the particle-based injection agent. Their tendency to form agglomerates in the suspension often requires the addition of organic dispersants (flow agents). Very fine cements are very expensive and to ensure a sufficient processing time, suspensions are often added to the suspensions; the processing effort and costs increase.

To ensure the ability to penetrate cracks and pores and have a sufficient pot life, the injectables have a high water to solid ratio and water to cement ratio. The suspensions are therefore immiscible with rock or pore solutions miscible. This effect can occur in particular in the case of injections if high flow velocities of the injection agent and thus turbulent flow conditions are present. Mixtures are known in particular from the field of tunnel construction and are referred to as leaching. The negative consequence of the mixing effect is a loss of the sealing effect or the mechanical bond to the injection body, i. the rock or the mining offset.

A further disadvantage is that the high proportions of water or solvents and the low viscosity of the mixing solution have the consequence that the particles of the suspensions sediment easily or particle filtrations can occur at bottlenecks of the flow path in the injection body. In addition, due to the different inertia (low viscosity of the solution phase) of the injection agent and the suspended particles as a result of pressure fluctuations in the injection process, a separation of the particles of the solution of the injection agent is possible. To prevent these processes and possibly a building material bleeding (formation of a solution layer on the building material surface), the addition of fine-grained swellable clays is often necessary, so that the cost and the cost of producing the injection agent increase.

The solutions present in cement-containing suspensions can furthermore dissolve rock constituents or physically react with rock constituents (such as clay fractions), so that swelling or cracking pressures arise. A disadvantage is that the chemical-physical interactions can affect the flow and thus the range of the injection agent in the corresponding cavity and above the non-positive connection of the injection agent with the injection body and the sealing effect. Reactions with external solutions, such as rock solutions, are highly dependent on the chemistry of these solutions for cementitious injectables. For sodium chloride-dominated solutions there is a risk of the above-described leaching and mixing of a delay in the setting reactions of the cement. Magnesium chloride, magnesium sulfate and calcium chloride, on the other hand, can initiate hardening and prevent further penetration of the injection front in the crack. The cementitious injectables react with a solution contact thus very sensitive to the different salts that can occur in mountain / formation solutions.

A major disadvantage of cementitious injection means is still their limited durability, long-term stability or long-term stability if magnesium, sulfate or ammonium ions are present in the rock solutions or if the solutions are acidic, for example due to dissolved carbon dioxide (CO2) (see DIN 4030). In this case, the injection agent can decompose, so that the functionality of the injections and thus the sealing or solidifying measure is no longer given.

In WO 2010/130582 A2 is an alkaline activated binder system is described, which is not free of organic components. DE 298 25 082 U1 describes an injection agent that is also not free of organic components. In DE 41 00 386 A1 is a described a molding material having a solidification and curing regulating and / or accelerating substance, which can cause rapid solidification and hardening in a short time, the molding material is used as a mortar mass in mining.

The object of the invention is to provide a use of an injection means for filling, solidifying and sealing pathways in a rock or a mining offset, especially in a mine, with the ensured in a simple manner a durable and reliable backfilling, solidification and sealing with a high long-term stability can be.

This object is achieved by an injection agent according to claim 1. Preferred developments are specified in the subclaims.

According to the invention, it is therefore intended to use as injection agent a mixture of a siliceous solution, for example a waterglass solution, and a binder system comprising at least granulated slag and / or metakaolin and / or silica fume, wherein the binder system is preferably activated alkaline or basic. That a dissolution reaction of the starting materials - granulated slag and / or metakaolin and / or silica fume - followed by solidification reaction to the binder system is carried out by an alkaline or basic activation.

Advantageously, with the injection medium according to the invention after hardening a good durability or long-term stability can be ensured. This could be confirmed experimentally, in that even after prolonged storage in different mountain solutions or saline rock solutions no adverse changes in the hardened injection medium could be found. Due to the negligible solubility, there are no adverse effects on the surrounding injection body, i. Loose or hard rock can be expected from groundwaters and formation solutions. Rather, it can be assumed that the salt content of numerous formation solutions is even conducive to the strength development of the injection medium according to the invention. Thus, reactions, for example, with highly concentrated salt solutions, e.g. MgCl2 solutions, cause an increase in the volume of solids, which is advantageous in terms of sealing pathways.

Since blastfurnace slag contains CaO, SiO 2 and Al 2 O 3, metakaolin SiO 2 and Al 2 O 3 and silica fume SiO 2, the content of the compounds SiO 2, Al 2 O 3 and CaO in the injection medium can be variably adjusted by the amount of the binder system starting materials used. The total amount of SiO 2 can also be adjusted via the composition of the siliceous acid-containing solution. As a result, the sealing effect as well as the solidifying effect of the injection agent can advantageously be adapted precisely to the filled rock or the filled mining offset.

The exact composition of the components of the injection agent depends in particular on the choice of the starting materials of the binder system:
If only blastfurnace slag is used for the binder system, the grout at a gravel content of the siliceous solution of 37/40 preferably has a first fraction of siliceous solution of at least 50 mass% and a second fraction of the binder system, ie of the blast furnace slag, of at most 50 masses -% on. If only metakaolin is used in the binder system, the first proportion is at least 60% by mass and the second proportion is at most 40% by mass. If the binder system consists only of silica fume, the first portion is selected to be at least 75% by mass and the second portion to a maximum of 25% by mass. These proportions are quasi-marginal values, ie not only is a starting material used for the binder system but a two- or three-component mixture of the starting materials granulated slag, metakaolin and silica fume, resulting in corresponding intermediate values for the first portion and the second portion.

At a gravel content of 50/52 of the siliceous solution, the respective boundary values change, whereby the first fraction increases by 5% by mass and the second fraction correspondingly decreases by 5% by mass. For grades between 50/52 and 37/40, the boundary values are to be chosen in between.

Furthermore, by selecting the fineness and the chemical reactivity in particular of the starting materials granulated slag and metakaolin advantageously the material property of Injection means, in particular the solidification property, are adapted to the respective application, so that an optimized filling or sealing can take place.

The starting materials are further referred to as additives of type II (reactive) according to DIN EN 206 and advantageously meet the quality requirements that are to be placed on starting materials for injectables. Silica fume (according to DIN EN 13263-1) as a starting material also has the advantage that the particles are about 30 to 100 times smaller than cement particles and therefore can penetrate into extremely small pathways, such as fine cracks and pores, of the injected system.

Water glass solutions, for example soda waterglass or potash waterglass, are in this case solutions of alkali metal silicates which are also used, for example, as particle-free injection agents and are therefore advantageously very suitable for filling, solidifying and sealing pathways in a rock or a mining offset. This water glass solution contained in the alkaline or base-activated injection agent can also penetrate into very fine cracks or pores, for example of the order of a few micrometers, which are not accessible to particles. In this case, advantageously, an additional sealing process takes place when the water glass solution comes into contact with salt solutions of the rock or when silica fume particles could penetrate into the fine cracks or pores. In this case, formed by the reaction of the injection agent, in particular the water glass solution, with the surrounding salt-containing rock a non-positive bond, which ensures a mechanical stabilization in the field of pathways.

According to an embodiment which is not part of the invention, it is provided to add, as an additional component of the injection means, a cementitious substance and / or magnesium oxide and / or to add to the injection agent a hardener which causes hardening of the waterglass solution. As a result, advantageously, the solidification properties of the injection agent can be further improved.

The use of cementitious materials in this case is in the injection of larger pathways, i. Cracks or pore systems in the mm to cm range, such as cavities, provided as in the reaction of cement with the water glass or the siliceous solution may form larger particles, or in combination with water glasses of high density or drought, d. H. low water content. The use of cement is therefore advantageously provided when a higher reaction / hardening rate of the injection agent is desired.

In addition to the cementitious materials or alternatively, the magnesium oxide can be added as an accelerating and / or strength-enhancing component.

Another area of use for the injection medium according to the invention with the additional cementitious substance comprises the filling and sealing of the boreholes used for injection. However, the amount of cement should be limited since it has been found that deposits may form at elevated levels in the flow shadows of the mixer or grout conveyor system.

Due to the chemical-mineralogical relationship with the starting materials of the binder system and the limited amount of Portland cement clinker as cementitious substance such as Portlandhüttenzement (CEM II / BS according to DIN EN 197-1), blast furnace cement (CEM 111, VLH 111), Portland silica dust cement or alumina cement be used according to DIN EN 14647.

With additional use of cement, the proportion of it in the injection medium is preferably set such that a Portland cement clinker content in the injection medium is at most 10% of the content of siliceous solution, i. of the first share.

It is advantageously achieved by the supplemental hardener that when the injectant is used in rocks which are inert, i. in which no reaction of the grout with the rock or the offset takes place, the water glass solution squeezed into fine cracks can nevertheless harden in order to achieve the effect of solidification and / or sealing. The hardener can penetrate with the siliceous solution in very fine, accessible only for solutions cracks and there cause a self-hardening of the water glass. Examples of possible hardeners are aluminates, fluoride-containing hardeners.

In accordance with an advantageous embodiment, inert additives, for example barite or clay flour (except bentonite) and / or additives, for example flow agents or reaction retarders, may furthermore be provided in the injection medium. Advantageously, this allows a further adaptation and optimization of the material properties to the injection requirements, for example, with regard to a flow or reaction behavior can be achieved. In addition, particles can act as proppant and keep flow paths open for the siliceous solution. Due to the requirement for flowability, however, the proportion of solvent always dominates over the solids content.

Advantageously, the injection means according to the invention can be used in combination with classical, particle-based injection means, even if these classic injection means contain a saline solution. At the contact surface between the inventive and the classical injection agent then forms a reaction layer with silica gels, which can be pressed into the crack or pore system. The result is an improvement in the sealing effect.

• 1 Injektionsarbeiten, bei denen ein Gestein mit einem Injektionsmittel verfüllt wird.

The invention will be explained in more detail with reference to a drawing. It shows:

• 1 Injection works in which a rock is filled with an injection medium.

The 1 shows schematically injection work where pathways 1a . 1b in a rock 2 in a mine, for example, by means of an injection 3 filled and sealed. This is first a hole 4 as an injection opening in the rock 2 brought. Subsequently, the injection agent 3 via an injection line 5 by a packer 7 leads and in the one valve 8th is placed in the borehole 4 pressed, the injection agent 3 with one of a pump 6 provided injection pressure pl is pressed.

In the rock 2 the injectant passes 3 depending on the composition and particle size of the injectant 3 and height of the injection pressure pl in smaller pathways 1a For example, fine cracks on the order of a few micrometers, and / or in larger pathways 1b For example, in cavities of a few millimeters to the centimeter range, wherein in the injection due to the injection pressure pl a solution proportion L , ie a low-solids content with silicic acid-containing solution and possibly silica dust particles, and a solids content F , ie a solids-rich fraction or a suspension, forms.

In particular, depending on the composition and grain size of the injectant 3 coarser particles remain in the larger pathways 1b and arrive at fine particle suspensions with finer particles, such as silica fume, and higher solution / solids ratio in the smaller pathways 1a , In the smallest pathways 1a the siliceous solution is pressed. The flow into increasingly fine cracks or pores leads to a decrease in the solids content F and the grain size of the further flowing suspension. In this way arise in the rock 2 the crack filling and a positive and non-positive bond, this mechanically stabilized (solidified) and / or for a sealing of the pathways 1a . 1b provides.

The injection pressure pl can be, for example, 80 bar, so that for a sufficiently high state of stress in the rock 2 is to be ensured, for example, by previously filling larger pathways 1b with lower injection pressures pl. For filling larger pathways 1b , also for closing the borehole 4 , the filling can be done with low injection pressures pl, the injection medium 3 Additionally, a cementitious substance may be added to increase the strength of the injectant 3 to increase.

Claims (10)

Use of an injection agent (3), comprising at least: silicic acid-containing solution and an alkaline activated binder system comprising at least granulated slag and / or metakaolin and / or silica fume, wherein the injection medium (3) is free of organic components for filling, solidifying and sealing pathways (1a, 1b) in a natural or artificial rock (2) or a mining offset in a mine. Use after Claim 1 , characterized in that the silicic acid-containing solution is alkaline, for example, water glass Use after Claim 2 , characterized in that is used as a water glass soda or glass of potassium silicate. Use according to one of the preceding claims, characterized in that the silicic acid-containing solution is adapted to react with the rock (2) or with the mining offset in the area to be filled pathways (1a, 1b) and / or as an additional component of the injection means (3 ) A hardener is provided for effecting hardening of the siliceous solution to form a frictional bond and / or for sealing the pathways (1a, 1b). Use after Claim 4 , characterized in that an aluminate or a fluoride-containing hardener is provided as a hardener. Use according to any one of the preceding claims, characterized in that the injection medium (3) further contains an inert additive, for example barite or clay flour, and / or an admixture, for example a flow agent for improving fluidity and avoiding grain agglomeration, or reaction retarder. Use according to one of the preceding claims, characterized in that the injection medium (3) has, as a first portion, at least 50% by mass of siliceous solution and, as a second proportion, a maximum of 50% by mass of blastfurnace slag. Use according to one of the preceding claims, characterized in that the injection medium (3) has as a first portion at least 60% by mass of silicic acid-containing solution and as a second proportion a maximum of 40% by mass of metakaolin. Use according to one of the preceding claims, characterized in that the injection medium (3) has, as a first fraction, at least 75% by mass of silicic acid-containing solution and, as a second component, a maximum of 25% by mass of silica fume. Use according to one of Claims 7 to 9 , characterized in that the graveliness of the siliceous solution is 37/40 or 40/42 or 48/50 or 50/52, wherein at a gravel of the siliceous solution of 50/52, the first portion to a meanness of 37/40 microns is increased by five mass% and the second fraction is reduced by five mass%.

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