CN106928952B

CN106928952B - Delayed crosslinking polymer system

Info

Publication number: CN106928952B
Application number: CN201511017535.0A
Authority: CN
Inventors: 廖文胜; 王立民; 李建华; 曹霖
Original assignee: Beijing Research Institute of Chemical Engineering and Metallurgy of CNNC
Current assignee: Beijing Research Institute of Chemical Engineering and Metallurgy of CNNC
Priority date: 2015-12-29
Filing date: 2015-12-29
Publication date: 2020-02-21
Anticipated expiration: 2035-12-29
Also published as: CN106928952A

Abstract

The invention relates to the technical field of in-situ leaching uranium mining processes, in particular to the technical field of a fluid control system for plugging a high-permeability channel or plugging a part of high-permeability layer in the in-situ leaching uranium mining process so as to control the leaching range of a leaching agent, reduce the consumption of a reagent and improve the recovery rate of uranium; the invention also relates to a delayed crosslinking depth profile control in oil exploitation; the invention relates to a delayed crosslinking polymer system, which comprises high molecular weight polyacrylamide, a phenolic crosslinking agent and a crosslinking retardant; according to the invention, by adjusting the addition of the crosslinking retardant, the crosslinking time can be controlled to achieve the effects of required injection amount and improving the leaching control range; the invention adopts a mode of adding a crosslinking retardant and provides a delayed crosslinking polymer system with low cost, simple preparation, low initial viscosity, adjustable gelling time and high gelling strength.

Description

Delayed crosslinking polymer system

Technical Field

The invention relates to the technical field of in-situ leaching uranium mining processes, in particular to the technical field of a fluid control system for plugging a high-permeability channel or plugging a part of high-permeability layer in the in-situ leaching uranium mining process so as to control the leaching range of a leaching agent, reduce the consumption of a reagent and improve the recovery rate of uranium; the invention also relates to a delayed crosslinking depth profile control in oil exploitation; the present invention relates to a delayed cross-linking polymer system.

Background

During the formation of sandstone-type uranium ores, ore bodies are often produced in sand bodies with relatively poor permeability, while surrounding rocks have good permeability. The characteristic enables the leaching agent to be easily lost along surrounding rocks outside the ore body when the leaching agent is injected into the ore bed, so that the waste and consumption of the agent are increased, and the ore body is difficult to effectively leach. Furthermore, even in the seam, the pore distribution is not uniform. Along with the continuous consumption of the reagent during leaching, the large pore passage is increased due to the good seepage capability of the large pore passage, the circulation performance of the large pore passage is improved, and the leaching is sufficient, so that the diluting capability of the leaching agent is strong, and the uranium concentration of the leaching solution is reduced; the small pore canals have poor seepage capability and low leaching rate, and the total recovery rate is also reduced under the dilution condition.

In order to increase the swept range of the leaching agent and improve the leaching effect, the leaching range of the leaching agent needs to be controlled. Currently, cross-linked polymers are an ideal method to block the wall rock or large pore canal of the deposit by using a polymer reagent to reduce the seepage capability of the wall rock or large pore canal.

Because the in-situ leaching uranium mining uses a plastic casing pipe, a fluid control agent is difficult to inject under large pressure and large flow, and a delayed crosslinking polymer system is required. At present, there are four main methods for delaying crosslinking systems:

firstly, a weak gel system is adopted, and the aim of delaying crosslinking is achieved by reducing the concentration of the polymer, which inevitably leads to lower system strength.

Secondly, the release of a cross-linking agent is controlled to delay the cross-linking reaction, and a mode of releasing formaldehyde by urotropine is commonly adopted, for example, CN1130439C adopts urotropine, oxalic acid and phenol as the cross-linking agent to delay the cross-linking; the release of the cross-linking agent can also be controlled by a physical mode, for example, CN102627953B adopts nano microcapsules to release the cross-linking agent within 3-20 days, while CN103602325A discloses a method for dissolving a competitive inclusion agent in a competitive inclusion agent carrier to generate competitive inclusion on phenol in a delayed cross-linking system and regulate the release speed of the phenol; generally, the method for controlling the release of the cross-linking agent has complex process and high construction cost.

Thirdly, the crosslinking agent system is improved, such as ZL90101715.9 which adopts aldehyde and salicylic acid derivative, so that the polymer system can delay crosslinking in a high-temperature stratum; CN102304354B uses dicyandiamide modified urea-formaldehyde resin to delay the cross-linking agent. The method has complex cross-linking agent and is difficult to be widely applied.

Fourthly, a mode of adding a retardant is adopted, for example, CN102965088A discloses an aluminum citrate cross-linked polymer system, which adopts a hydrophobic association polymer, and a retarder is sodium malate; the method is simple to apply, but the cross-linking strength and the effect of delaying the cross-linking action are limited at present.

Disclosure of Invention

Aiming at the prior art, the invention aims to provide a delayed cross-linking polymer system to solve the problems of low strength, complex cross-linking agent, complex method and process for controlling the release of the cross-linking agent, high construction cost and the like of the delayed cross-linking polymer system in the prior art.

In order to solve the technical problems, the invention provides a delayed crosslinking polymer system, which comprises an aqueous solution formed by a high molecular weight polyacrylamide polymer, a phenolic crosslinking agent and a crosslinking retardant; the crosslinking retardant is tallow dihydroxyethyl betaine.

Further, normally preparing a high-molecular polyacrylamide polymer and a phenolic crosslinking agent aqueous solution, and adding 20-1000mg of crosslinking retardant into each liter of aqueous solution formed by the high-molecular polymer and the phenolic crosslinking agent under a normal temperature environment.

Further, the crosslinking retardant was used in an amount of 100-500 mg.

Further adding 1-5g of high molecular weight polyacrylamide polymer into each liter of water; the addition amount of the phenolic aldehyde crosslinking agent is 10-14g per liter of water.

Further, the high molecular weight polyacrylamide polymer is anionic polyacrylamide.

Further the high molecular weight polyacrylamide polymer is a partially hydrolyzed anionic polyacrylamide.

Further, the phenolic crosslinking agent is formaldehyde and benzenediol.

The application of the tallow dihydroxy ethyl betaine as a crosslinking retardant is that the tallow dihydroxy ethyl betaine is added into the aqueous solution of the high molecular weight polyacrylamide polymer and the phenolic crosslinking agent to delay the crosslinking of the high molecular weight polymer in the normal temperature environment.

Further adding 20-1000mg of crosslinking retardant into each liter of aqueous solution formed by the high molecular weight polyacrylamide polymer and the phenolic crosslinking agent under normal temperature environment.

Further, the crosslinking retardant was used in an amount of 100-500 mg.

Further, the phenolic crosslinking agent is formaldehyde and benzenediol.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

the delayed crosslinking polymer system has the advantages of low cost, simple preparation, low initial viscosity, adjustable gelling time and high gelling strength.

In the in-situ leaching uranium mining process, the polymer cross-linking system for plugging a high-permeability layer or a large pore channel can improve the leaching efficiency and the recovery rate of metals by controlling the flow route or range of fluid.

The invention adopts a mode of directly adding a crosslinking retardant to delay the crosslinking of the polymer so as to achieve the purposes of convenient injection and crosslinking time control; according to the use requirement, the dosage of the crosslinking retardant is adjusted, and the crosslinking time can be controlled, so that the mining requirements of different uranium leaching mines can be met.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

The delayed crosslinking polymer system comprises a water solution formed by a high-molecular polyacrylamide polymer, a phenolic crosslinking agent and a crosslinking retardant;

the addition amount of the high molecular polymer is 1-5g per liter of water, and the preferable addition amount is 1.5g per liter of water; the high molecular polyacrylamide polymer is anionic polyacrylamide, the hydrolysis degree of the anionic polyacrylamide is 10-35%, and the partially hydrolyzed anionic polyacrylamide is preferred;

the adding amount of the phenolic aldehyde crosslinking agent is 10-14g per liter of water, preferably 12g per liter of water, the phenolic aldehyde crosslinking agent is preferably prepared from formaldehyde and benzenediol, and the formaldehyde and the benzenediol are preferably prepared in a ratio of 1: 1;

the crosslinking retardant is tallow dihydroxyethyl betaine (CAS number 70750-46-8);

when in use, the addition amount of the crosslinking retardant is 20-1000mg in each liter of aqueous solution formed by the high molecular polymer and the phenolic crosslinking agent under the normal temperature environment; preferably, the crosslinking retardant is used in an amount of 100-500 mg.

The following description will be made by taking an example of adding 0.3g of anionic polyacrylamide to 200ml of water, and then adding 1.2g of each of benzenediol and formaldehyde to prepare an aqueous solution, and adding different amounts of crosslinking retardant to illustrate the effect of the crosslinking retardant on the crosslinking of the polymer. It should be noted that the present invention is not limited to the above-mentioned solution ratio of the polymer system.

Example 1

Adding 200ml of water into a beaker, then adding 0.3g of anionic polyacrylamide, then adding 1.2g of each of benzenediol and formaldehyde, then adding 4mg of a crosslinking retardant tallow dihydroxy ethyl betaine, uniformly stirring, and crosslinking at room temperature; the viscosity changes with time are shown in Table 1.

Example 2

Adding 200ml of water into a beaker, then adding 0.3g of anionic polyacrylamide, then adding 1.2g of each of benzenediol and formaldehyde, then adding 100mg of a crosslinking retardant tallow dihydroxy ethyl betaine, uniformly stirring, and crosslinking at room temperature; the viscosity changes with time are shown in Table 1.

Example 3

Adding 200ml of water into a beaker, then adding 0.3g of anionic polyacrylamide, then adding 1.2g of each of benzenediol and formaldehyde, then adding 200mg of a crosslinking retardant tallow dihydroxy ethyl betaine, uniformly stirring, and crosslinking at room temperature; the viscosity changes with time are shown in Table 1.

Comparative example 4

Adding 200ml of water into a beaker, then adding 0.3g of anionic polyacrylamide, then adding 1.2g of each of benzenediol and formaldehyde, adding no crosslinking retardant, stirring uniformly, and crosslinking at room temperature; the viscosity changes with time are shown in Table 1.

TABLE 1 viscosity of Polymer systems at different concentrations of Cross-linking retarder

Note: the initial viscosity of the system is 35mPa.s, room temperature, and the measurement is carried out in parallel. Shanghaiengaceae SNB-2 digital viscometer.

The above examples show that the crosslinking retardant tallow dihydroxy ethyl betaine prolongs the crosslinking time. By adjusting the addition of the crosslinking retardant, the crosslinking time can be controlled to achieve the effects of required injection amount and improving the leaching control range.

Claims

1. A delayed crosslinking polymer system comprising an aqueous solution of a polyacrylamide polymer, a phenolic crosslinker, and a crosslinking retardant; the crosslinking retardant is tallow dihydroxyethyl betaine;

normally preparing an aqueous solution of a polyacrylamide polymer and a phenolic crosslinking agent, and adding 20-1000mg of a crosslinking retardant into each liter of the aqueous solution formed by the polymer and the phenolic crosslinking agent under a normal temperature environment;

the adding amount of the polyacrylamide polymer is 1-5g per liter of water; the addition amount of the phenolic aldehyde crosslinking agent is 10-14g per liter of water.

2. The delayed crosslinking polymer system of claim 1, wherein the crosslinking retardant is used in an amount of 100-500 mg.

3. The delayed crosslinking polymer system of claim 1, wherein the polyacrylamide polymer is an anionic polyacrylamide.

4. The delayed crosslinking polymer system of claim 3, wherein the polyacrylamide polymer is a partially hydrolyzed anionic polyacrylamide.

5. The delayed crosslinking polymer system of claim 1, wherein the phenolic crosslinker is formaldehyde and hydroquinone.

6. The application of the tallow dihydroxyethyl betaine as a crosslinking retardant is characterized in that: under normal temperature environment, tallow dihydroxy ethyl betaine is added into the polyacrylamide polymer and the aqueous solution of the phenolic crosslinking agent to delay the crosslinking of the polymer.

7. Use of tallow dihydroxy ethyl betaine as a cross-linking retardant according to claim 6, wherein: under normal temperature, 20-100mg of crosslinking retardant is added into each liter of aqueous solution formed by the polyacrylamide polymer and the phenolic crosslinking agent.

8. Use of tallow dihydroxy ethyl betaine as a cross-linking retardant according to claim 7, wherein: the amount of the crosslinking retardant used is 100-500 mg.