RU1838214C - Method of liquid wastes underground storage - Google Patents

Abstract

The invention relates to underground storage of liquid waste products. The method involves the selection and accumulation of liquid waste in surface storage tanks by pumping them through a mine. It is characterized in that liquid waste is pumped into low-permeable rocks chemically soluble in stored waste and lying in an adjacent area with an aquifer. During injection, a cyclic change in pressure is carried out, the rock-separating layer is crushed and the injected waste is forced into the aquifer. 5 ill.

Description

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The invention relates to the protection of the environment from pollution by liquid wastes of mining, chemical and other industries and can be used for $ || storage of drainage brines.

| The aim of the invention is to reduce the cost of warehousing due to the progressive increase in the pick-up of the mine

 Figure 1 shows a diagram of the implementation of the proposed method; Figure 2 shows the dynamics of leaching of the most common halogen rocks, depending on the concentrate. the liquid waste M; in Fig. 3, depending on (|; the relative volume of leaching QO; OT of the concentration of liquid waste M; by% phiM, the dependence of the relative volume of dissolution of halogen rocks Q0 on the temperature t ° C of liquid waste (drainage brines) (at a concentration of 150 g / l and a dissolution time of 50 hours); Fig. 5 shows the dynamics of the radius R4 of the expanding chamber.

Underground storage of liquid waste by the proposed method is as follows.

In a production area (for example, a mining enterprise), liquid waste is collected and accumulated in surface storage tanks 1. Then they are pumped into highly soluble impermeable rocks 2 adjacent to an absorbing aquifer 3 through mining 4.

Well-soluble, impermeable, rocks are understood as high-icy deposits, as well as rocks forming

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at the final stages of halogenesis, sodium and potassium chlorides and sulfates, deposits represented by a high content of minerals such as halite, sylvin, carnalite, polygalite, tenardite, mirabilite, gypsum, 5 glauberite, soda, etc. When liquid products are injected, good leaching occurs - Shore-soluble rocks and the formation of caverns in them (5).

It can be seen from Figs. 2 and 3 that the rate and volume of 10 dissolution of halogen rocks are practically independent in the range of 50-150 g / l from the concentration of salts of liquid waste.

During the injection, the pressure in the forming cavity is cyclically changed. 15 Cyclic loads lead to an increase in cracking in the ceiling 7, represented by a separating layer. When critical pressure drops are reached, formation water breaks into the cavity, i.e. 20 collapse of the rocks and creation of a direct hydraulic connection between the cavern and the absorbing aquifer. Hardened rocks 6 of the borehole zone 25 and an impenetrable separation layer (between the reservoir and the absorbing collectors) collapse into the formed chamber. Thereby, an increase in the efficiency of the radius of the well is produced, which leads to an increase in injectivity 30 of the production.

In order to increase the efficiency of destruction of the separating layer, which is usually represented by clay rocks, and leaching of soluble rocks, liquid wastes in a storage tank or during transportation 8 are cooled (heated) by atmospheric air. When soaking with fresh and slightly mineralized wastes, a decrease in the strength properties of the 40 separating layer is achieved due to the wedging effect of thin films of water. Due to the sharp difference in the thermal expansion coefficients of the minerals composing them, the injection of waste that differs in temperature by massif leads to significant and uneven volumetric stresses.

Lowering the temperature leads to a decrease in the hydration of the ions of the solution, in connection with which the electrostatic interaction forces of these ions with the free charges of clay minerals increase. Due to this factor, ion diffusion coefficients increase by an order of magnitude and 55 more, increasing the penetration depth into the array and the hydrochemical variability of the solution. Therefore, uneven volume osmotic stresses occur in the separate layer. Positive

the consequence of lowering the temperature is limited to the eutectic point of one of the most common salts in liquid waste - sodium chloride (ta -20 ° C). Upon further cooling, crystalline hydrates, ice and the like are formed in the solution, which sharply reduce the diffusion coefficients of the ions and their aggressiveness.

P r and measures. The method was carried out in one of the diamond deposits of Western Yakutia, the hydrogeological conditions of which are characterized by the presence in the section of a pressure-bearing aquifer complex lying in the depth interval 300-500 m, having an average thickness of 180 m, water conductivity of 70 m2 / day. The horizon contains hydrogen sulfide chlorine-sodium water with a salinity of up to 120 g / l. Liquid wastes represent drainage brines whose discharge into the river network is short. empty due to their high toxicity and mineralization. Drainage brines have a sodium chloride composition; significantly contaminated with iron compounds and petroleum products.

Permanent frozen rocks with a thickness of up to 350 m are the upper confinement of the complex. The lower confinement is thicker than carbonate-halogen deposits with a thickness of 400-450 m. It has been established that there are no other aquifers in the area of the deposit that can take the required volume of drainage brines .

Drainage brines are collected through drainage wells and open pit drainage. Drainage brines are fed through a water conduit in the injection area and stored in a temporary settling tank, where they are partially freed from mechanical suspensions and degassed.

Vertical wells are drilled, the bottom of which reveals halogen rocks below the aquifer to a depth of 65 m. Wells are equipped with filtrates in the interval of halogen rocks and absorbing reservoirs. A water supply column is lowered inside the filter pipes, through which drainage brines are fed from the reservoir. Brines, rising in the annulus, interact with the salts, their solution.

Preliminary washing is carried out by feeding brines of 5-15 m3 / h with a gradual increase in flow rate. The pressure at the wellhead is maintained in the range of 15-20 atm.

When waste is pumped into the base of the aquifer, a chamber forms, the radius of which is constantly increasing ($ ig. 5).

 As the chamber volume increases, sharp discharges and rises of fluid pressure (RP) are periodically made into the well (5 and the chamber, as a result of which the rocks (lying over the roof of the tank are destroyed.) The ultimate pressure at which water breaks into a cavity, they are calculated according to the formula

-

 m

Wo

(Y +

2C

B - Ј tg p max

)

where S and r t - grip and angle of internal friction;

Ј is the lateral pressure coefficient; luo -volume weight of rock and water; b is the diameter of the cavity; m - thickness of water-resistant rocks for our case

Rpr 12-15 kg / cm2.

As a result of collapse, the area of the consoles and the aquifer increases and the brines flow into the aquifer.

; For more intensive leaching | salts, the temperature of injected traces changed seasonally. In the summer period, due to the heating of the bed by atmospheric, warm, when transported through a water conduit, the brines have a temperature above + 5 ° C, and in the winter time the brines are cooled to a temperature} below -5 ° C.

Due to hardening by brines with different temperatures in the leachable capacity of the noJMHMO salt dissolution, temperature destruction occurs, microcracks are formed, which leads to an intensification of the useful volume of the chamber and self-crumbling.

 When implementing the proposed method, the diameter of the chamber reaches 100-150 m. After the collapse of the rocks of the separating layer and its connection with the absorbing

by the collector, the effective working radius increases to 25–40 m, i.e. increases in comparison with the original 107-1012 times. (The effective radius of the well (diameter of drilling is 152 mm) in conditions of diamond deposits in Western Yakutia is - m). In this case, the pick-up of the output increases in proportion to the natural logarithm of the ratio of effective radii, i.e. 15-25 times. Therefore, a single production can replace the system of standard absorbing wells.

To monitor the disposal process, absorption rates are monitored.

5 pressure at the mouth of the mine. To control the size of the chamber, acoustic logging, hydrochemical and hydrodynamic studies in the production are periodically carried out. When the working height reaches more than 1/3 of the initial depth of the well, collapse and leaching are stopped to avoid subsidence of the earth's surface.

Claims (2)

1. A method of underground storage of liquid waste products, including the selection and accumulation of liquid waste in surface storage, pumping them through a mine into a rock mass with dissolution of the latter and the formation of a cavity, characterized in that, in order to reduce the cost of storage due to a progressive increase in mine susceptibility and from dissolution when adjacent to the array. rocks of the aquifer, liquid; This waste material is pumped into low-permeability rocks, chemically soluble in the stored waste material adjacent to the aquifer, and when injected, they undergo a cyclic change in pressure, break down the rock-separating layer and displace the injected waste material into the aquifer. 2. A method according to claim 1, characterized in that the liquid waste is pumped seasonally with positive and negative temperatures. 100 80 60 w U 20 30 40 50 60 70 80 t, ciao FIG. 2 M - 0.2 G / A 150 rA 50 g / 100 g / a M - 200g 80 60 fifty Q0- 95 90 85 80 75 70 65 60 -55 50 45 + 20 +15 +10 +5 0 -5. -10 t ° C 1 Fig. 4 100 Fig. 3 150 200N / L H 200 150 100 502 H 6 8 10 FIG. 5 t years