Composition for chemically treating the near-filter region of wells for the in-situ leaching of uranium

Abstract

The invention relates to mining and can be used in the stimulation of downhole uranium recovery by in-situ leaching. The technical result of the invention is that of obtaining a composition for chemically treating the near-filter region of wells for the in-situ leaching of uranium, and of developing a composition for chemically treating the near-filter region of wells for the in-situ leaching of uranium that permits an increase in the productivity and injectivity of production wells. The claimed technical result is achieved in that a composition for chemically treating the near-filter region of wells for the in-situ leaching of uranium is claimed which contains hydrofluoric acid and sulphuric or hydrochloric acid, wherein the components of the composition are present in the following mass fractions: 50.0-98.0% sorption mother liquor or process water or leaching solution; 1.0-40.0% hydrofluoric acid; 1-10% sulphuric or hydrochloric acid.

Description

[0001] COMPOSITION FOR CHEMICAL TREATMENT OF THE NEAR-FILTER ZONE OF URANIUM UNDERGROUND LEACHING WELLS

[0002] The invention relates to mining and can be used to intensify uranium mining wells using the underground leaching method.

[0003] State of the art.

[0004] A method for intensifying underground leaching of uranium is known (KZ 32822, published, bulletin No. 20 dated 04.06.2018), including feeding a leaching solution containing sulfuric acid with a concentration of 3-7 g / l into an injection well, characterized in that it includes preliminary treatment of the injection and pumping well with an aqueous 1% solution of ammonium bifluoride, simultaneously with feeding into the injection well, the leaching solution is fed through the pumping well into the productive horizon, the solution is forced into the wells at a pressure of 2-6 bar, kept in the well for up to 14 days, then the productive solution is withdrawn from the pumping well, while the leaching solution additionally contains (wt.%) sulfamic acid - 1; lignosulfonate - 2; trisodium polyphosphate. The disadvantages of this method are its low dissolving capacity of sediment-forming components consisting of gypsum, carbonate, clay minerals and sand, as well as the high cost of ammonium bifluoride.

[0005] A method is known for decolmatation of filters and the near-filter zone of wells during their operation, including the treatment of wells with chemical reagents containing acidic components. To carry out the treatment, technical table salt is poured through the wellhead, then sulfuric acid is poured in, while the volumes of salt and sulfuric acid solution are selected based on the stoichiometry of the chemical reaction of hydrochloric acid formation. After that, the resulting column of liquid is squeezed out by feeding mother solutions and the well is maintained in this mode for 24-36 hours (Patent of the Republic of Kazakhstan No. 15427, Method of decolmatation of filters and the near-filter zone of wells during their operation / Dzhakishev M.E., Kim A., Ibraev B.M., Rogaev S.V., Utarbaev G.K., Altynbek A.D.; published 17.09.2007, Bulletin No. 9). The disadvantage of this method is its low efficiency in complex geological conditions with high carbonate and clay content of the productive horizon.Since HCl is formed in the well during the treatment of salt with sulfuric acid, the process is accompanied by the formation of insoluble precipitates of calcium and magnesium sulfate (Ca(Mg)SO4), as well as swelling of clay minerals under the influence of free sodium ions, which complicates the PSV and subsequent restoration of the permeability of the BZP.

[0006] A method is known for treating filters and the bottomhole zone of in-situ leaching wells, which includes feeding a flushing fluid and a leaching solution into the injection wells. The flushing fluid is prepared in two types - loosening and dissolving. The flushing loosening fluid, leaching agent, and flushing dissolving fluid are pumped in succession, and after the formation absorbs the solutions, the leaching solution is re-injected. The flushing fluid contains (wt. %) surfactant - 0.005-0.01, trisodium polyphosphate - 0.05-0.1, sorption mother liquor - the rest; The washing and dissolving liquid contains (wt. %) trisodium polyphosphate - 0.05-0.1, sulfamic acid - 0.06-0.125, sorption mother liquor - the rest (Patent of the Republic of Kazakhstan No. 29034, Method for treating filters and the bottomhole zone of underground leaching wells / Mamytbekov G.K., Kozhakhmetov S.K., Shavanda V.V.; published 05 / 29 / 2015, Bulletin No. 5).The disadvantage of this method is the low efficiency of the flushing fluid in wells with dense chemical sediments on filters and in the bottomhole formation zone. The activity of these chemical reagent compositions is insufficient for dissolving and dispersing dense gypsum or clay sediments under formation pressure.

[0007] A composition for decolmatizing treatment of production wells in uranium in-situ leaching conditions is known, containing hydrochloric acid and surfactants. The supply of the claimed decolmatizing composition through the wellhead increases the permeability of the productive horizon, increases well productivity and extends the well overhaul cycle. The result is ensured by the high reactivity of hydrofluoric acid with chemical sediments and clay particles. The additional use of surfactants increases efficiency by reducing interfacial tensions and increasing spreading in the bottomhole zone. (Patent of the Republic of Kazakhstan No. 32021 Composition for decolmatizing treatment of uranium in-situ leaching wells / Matayev M.M., Kenzhetayev Zh.S., Shavanda V.V., Aitenov S.M., Tretyakov S.Yu. - published 28.04.2017, Bull.No. 8) The disadvantage of this method is that the declared composition does not 33982 3 ensure an increase in the concentration of uranium in the PR and does not affect the oxidation-reduction parameters of the solutions.

[0008] The closest analogue-prototype is a composition for intensifying underground borehole leaching of uranium and a method for its use, which includes recovery, which is carried out by preliminary treatment of the process well with an aqueous 1% solution of ammonium bifluoride. Simultaneously with the feeding of the composition into the process well, a leaching solution containing sulfuric acid with a concentration of 3-7 g / l and chemical reagents (wt.%) - sulfamic acid - 1, lignosulfonate - 2, trisodium polyphosphate - 3 is fed into the productive horizon, the solution is forced into the wells at a pressure of 2-6 bar, kept in the well for up to 14 days, then the productive solution is withdrawn from the process well (Patent of the Republic of Kazakhstan No. 32822 Method for intensifying underground borehole leaching of uranium / Kosunov A.A., Kopbaeva M.P., Myrzabek K.A., Mataev M.M., Kenzhetaev Zh.S., Berdaliev B.A., Kalmaganbetov E.Z., Arystanbekov A.M., Zhumakanov N.M., Abdrakhmanov N.N. - published 04.06.2018, Bulletin No. 20).The disadvantages of the known composition and method are low efficiency in complex geological conditions with high carbonate and clay content of the productive horizon, near-filter zone of wells. Low productivity of wells and concentration of uranium in PR leads to a decrease in the intensity of development of production blocks.

[0009] The technical result of the invention is obtaining a composition for chemical treatment of the near-filter zone of wells for underground leaching of uranium and a method for using it. Development of a composition for chemical treatment of the near-filter zone of wells for underground leaching of uranium, which allows increasing the productivity and injectivity of process wells. Also increasing the inter-repair cycle (IRC), the period of uninterrupted operation of wells, reducing the period of block development, reducing operating costs, sulfuric acid, electricity at the stages of preparation and development of production blocks in various mining and geological conditions during underground borehole leaching of uranium.

[0010] The declared technical result is achieved by the fact that a composition for chemical treatment of the filter zone of underground leaching wells is declared, consisting of hydrofluoric acid, sulfuric acid or hydrochloric acid, and the composition consists of the following ratio of components by mass fraction:

[0011] - sorption mother liquor or technical water or leaching solution 50.0 - 98.0%,

[0012] - hydrofluoric acid 1.0 - 40.0%,

[0013] - sulfuric or hydrochloric acid 1-10%.

[0014] In one of the particular versions of the composition for chemical treatment of the filter zone of underground leaching wells, it additionally contains surfactants in a ratio of 0.1 - 10.0% of the mass fraction of the composition.

[0015] The claimed invention also relates to a method for chemically treating the near-filter zone of in-situ leaching wells, including feeding a flushing liquid, a leaching solution into the injection wells, characterized in that a decolmatizing solution is prepared by connecting a sorption mother liquor pipeline, or process water, or a leaching solution to a mobile tank on mobile equipment, the shut-off valves are opened and the tank is filled to 50.0 - 98.0% by weight with a solution containing hydrofluoric acid and sulfuric or hydrochloric acid, wherein hydrofluoric acid in an amount of 1.0 - 40.0% by weight, and sulfuric or hydrochloric acid 1- 10% by weight is fed alternately by temporarily opening and closing the shut-off valves, after disconnecting the pipelines from the tank and checking the equipment for readiness for transportation, the installation is moved according to the assignment to the well, after installing the mobile equipment on the well,the pressure hose is lowered into the filter zone and the transfer pump is turned on for the metered supply of the decolmatizing solution and the tank is emptied; after the process of supplying the required volume of decolmatizing solution is completed, the pressure hose is rolled up and checked for readiness for transportation to the next well or refilling.

[0016] In one embodiment of the method for chemical treatment of the filter zone of underground leaching wells, after the decolmatizing solution is fed into the process well, it is held, then compressor pumping is performed until the solution is completely clarified.

[0017] The claimed invention is explained by the following figures of the drawing.

[0018] Fig. 1 - Scheme of the implementation of the method of chemical treatment of the filter zone of wells.

[0019] Fig. 2 - Schematic diagram of the method for preparing a solution with separate containers.

[0020] The following elements are shown in figures 1 and 2:

[0021] 1 - productive horizon;

[0022] 2 - impermeable rocks;

[0023] 3 - sedimentation in the near-filter zone of the formation;

[0024] 4 - pumping well;

[0025] 5 - injection well;

[0026] 6 - equipment for chemical treatments;

[0027] 7 - pressure hose;

[0028] 8 - capacity - tank.

[0029] According to Fig. 1-2, the preparation of decolmatizing solutions is mechanized without interaction of decolmatizing solutions and their vapors with the environment and service personnel. The operator at the filling point connects the pipeline of the sorption mother liquor / process water / leaching solution to the mobile tank (8), opens the shut-off valve and fills the tank by 50% in a volume of 1500 kg, with a solution containing sulfuric or hydrochloric acid, after which he temporarily closes the shut-off valve. Next, the operator connects a flexible hose from the hydrofluoric acid tank pump to the tank, opens the shut-off valve and turns on the pump for loading hydrofluoric acid into the mobile tank (8) in an amount of 150 - 1000 kg, depending on the task. Next, the operator disconnects the flexible hose branch pipe from the hydrofluoric acid pipeline and opens the shut-off valve with the sorption mother liquor / process water / leaching solution and fills the mobile tank according to the task.After disconnecting the pipelines and checking the equipment for readiness for transportation, the operator moves the unit to the well as assigned. After installing the mobile equipment (6) on the well, the operator lowers the pressure hose (7) into the filter zone (3) and turns on the transfer pump for the metered supply of the decolmatation solution and emptying the tank. After completing the process of supplying the required volume of decolmatation solution, the operator reels the pressure hose and checks for readiness for transportation to the next well or refilling.

[0030] Figure 2 shows the method of preparing a solution with separate containers of decolmatizing solutions / sorption mother liquors / technical water / leaching solution. The required amount of sulfuric acid and hydrofluoric acid is fed into a mobile chemical processing unit with a container through a pump for pumping acidic solutions, which is pre-filled with decolmatizing solutions from the container (6) by 40-50%.

[0031] Examples of implementation of the invention.

[0032] According to the invention, the composition for chemical treatment of the near-filter zone of underground leaching wells contains hydrofluoric acid, sulfuric or hydrochloric acid in the following ratio of components (mass fractions): hydrofluoric acid 1.0 - 40.0%, sulfuric or hydrochloric acid 5.0 - 10.0%. To improve the adhesive properties, it is possible to use surfactants in a ratio of 0.1 - 10.0%, the rest is sorption mother liquor or process water or leaching solution, for example:

[0033] Example 1.1. Composition for chemical treatment of the near-filter zone of in-situ leaching wells, consisting of hydrofluoric acid, sulfuric or hydrochloric acid. According to the invention, the composition for chemical treatment of the near-filter zone of in-situ leaching wells contains hydrofluoric acid, sulfuric or hydrochloric acid in the following ratio of components (mass fractions): - hydrofluoric acid 5.0%,

[0034] - sulfuric acid 5.0%,

[0035] - sorption mother liquor - 90%.

[0036] Example 1.2. Composition for chemical treatment of the near-filter zone of in-situ leaching wells, consisting of hydrofluoric acid, sulfuric acid or hydrochloric acid. According to the invention, the composition for chemical treatment of the near-filter zone of in-situ leaching wells contains hydrofluoric acid, sulfuric acid or hydrochloric acid in the following ratio of components (mass fractions):

[0037] - hydrofluoric acid 13.5% (405 kg),

[0038] - sulfuric acid 21.66% (650 kg),

[0039] - sorption mother liquor - 64.84% (1945 kg).

[0040] Example 2.1 Composition for chemical treatment of the near-filter zone of in-situ leaching wells, consisting of hydrofluoric acid, sulfuric acid or hydrochloric acid. According to the invention, the composition for chemical treatment of the near-filter zone of in-situ leaching wells contains hydrofluoric acid, sulfuric acid or hydrochloric acid in the following ratio of components (mass fractions):

[0041] - hydrofluoric acid 2%,

[0042] - hydrochloric acid 5%,

[0043] - sorption mother liquor - 93%.

[0044] Example 2.2. Composition for chemical treatment of the near-filter zone of in-situ leaching wells, consisting of hydrofluoric acid, sulfuric acid or hydrochloric acid. According to the invention, the composition for chemical treatment of the near-filter zone of in-situ leaching wells contains hydrofluoric acid, sulfuric acid or hydrochloric acid in the following ratio of components (mass fractions):

[0045] - hydrofluoric acid 5.4% - (162 kg),

[0046] - hydrochloric acid 13.5% (405 kg),

[0047] - sorption mother liquor - 81.1% (2433 kg).

[0048] The preparation of a composition for chemical treatment of wells and the near-filter zone of the productive horizon with the inclusion of hydrofluoric acid provides for the use of a new and different composition for chemical treatment of wells and the near-filter zone based on hydrofluoric acid in the specified concentrations, as well as a method of preparation, which creates conditions for the most contactless method of preparation. Chemical treatment of wells and the near-filter zone of the productive horizon will be carried out using existing methods, either from the wellhead or directly into the filter part of the well.

[0049] The method of chemical treatment of the filter zone of underground leaching wells is carried out in such a way that after the decolmatizing solution is fed into the process well, it is held, after which compressor pumping is carried out until the solution is completely clarified.

[0050] Table 1. Average results of pilot industrial repair and restoration works of wells using ammonium bifluoride, hydrofluoric acid of different compositions based on the Northern Kharasan field.

[0051] Table 1 shows that when using different compositions for chemical treatment of wells and the near-filter zone of the productive horizon, consisting of hydrofluoric acid, sulfuric acid and surfactants, a technical result is observed in the form of an increase in the average MRC as a whole by 18-25%.

[0052] The validity of the claimed technical result of the invention is explained by the fact that a method is proposed for chemical treatment of the filter zone of wells, dissolving sand and colmatation sediments, clay crust, which is achieved by hydrofluoric acid, which interacts with aluminosilicates and siliceous compounds, which are a component of ore-bearing rocks and colmatation sediments.:

[0053] CaAhSiOs + 16HF = 2A1F3+ 2SiF4+ 8H2O + CaF2,

[0054] 6HF + SiO2= SiF4+ 2 HF + 2H2O

[0055] As a result, both the colmatant and part of the terrigenous component of the sands dissolve, generally increasing the effective porosity of the ore block massif. At the same time, hydrofluoric acid is completely utilized due to the large amount of quartz contained in the sands.

[0056] This method can be used for chemical treatment of the filter zone of wells in both pumping and universal wells and in injection wells.

Claims

Formula 1. A composition for chemical treatment of the near-filter zone of underground leaching wells consisting of hydrofluoric acid, sulfuric or hydrochloric acid, characterized in that it consists of the following ratio of components by mass fraction: sorption mother liquor or process water or leaching solution 50.0 - 98.0%, hydrofluoric acid 1.0 - 40.0%, sulfuric or hydrochloric acid 1-10%.

2. A composition for chemical treatment of the near-filter zone of underground leaching wells according to I.1, characterized in that it additionally contains surfactants in a ratio of 0.1 - 10.0% of the mass fraction of the composition. 8

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