CN114195451A

CN114195451A - A kind of preparation method of nanocellulose reinforced filling slurry

Info

Publication number: CN114195451A
Application number: CN202111501670.8A
Authority: CN
Inventors: 付建新; 宋卫东; 汪杰
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2022-03-18

Abstract

The invention provides a preparation method of nano-cellulose reinforced filling slurry, belonging to the technical field of mining filling. Mechanically stirring and uniformly mixing nano cellulose dry powder and sodium carboxymethylcellulose (CMC) powder, simultaneously performing ultraviolet irradiation treatment, adding the mixture into a filling bin through a feeder, and mixing and stirring; and after the slurry is uniformly stirred, pumping the filling slurry to an underground goaf through a pipeline for filling construction. According to the invention, the filling slurry is enhanced by compounding the nano-cellulose and the sodium carboxymethyl cellulose, the nano-cellulose can effectively improve the hydration degree of the slurry, improve the water retention property and the workability of the slurry, and greatly increase the compactness and the strength of a filling body, the sodium carboxymethyl cellulose is beneficial to the dispersion of the nano-cellulose, the flocculation and sedimentation of tailings are accelerated, the concentration of the filling slurry is increased, and the compactness of the filling body is increased, so that the mechanical property of the filling slurry is improved, and the filling cost is reduced.

Description

Preparation method of nano-cellulose reinforced filling slurry

Technical Field

The invention relates to the technical field of mining filling, in particular to a preparation method of nano-cellulose reinforced filling slurry.

Background

Deep mining is the inevitable trend of future mining development, and the deep mining faces complex engineering geological environment, especially earth pressure disaster caused by high ground stress, and is one of the core problems of the future deep mining. In order to effectively solve the problem of ground pressure in deep mining, the filling method is one of the first mining methods for deep ore bodies.

The filling mining method is characterized in that after mining of ore bodies is finished, a formed goaf is filled to support surrounding rocks, and sudden caving damage of the goaf is prevented, so that cascading disaster is caused. The commonly used filling material is mainly characterized in that mine tailing solid waste, cement and water are mixed according to a certain proportion to form slurry with a certain concentration, the slurry is conveyed into a goaf through a pipeline, the filling slurry has a certain strength after being solidified, and the effects of supporting surrounding rocks, controlling deformation, transferring stress and the like can be realized.

However, as the mining depth continues to increase, the strength of the pack is increasingly required, and the main reasons for affecting strength include the amount of cement used, the slurry concentration, groundwater, and management. In order to meet the requirement of deep mining on filling, a paste filling method is generally adopted, namely a filling station is transformed or reconstructed, a deep cone thickener is adopted to replace a traditional sand silo, the slurry concentration can be effectively improved, the strength of a filling body is improved, and a large amount of practical production experience shows that the method has a good effect.

Meanwhile, the quality of the filling body is improved by adding additives, such as fiber reinforced materials (glass fibers, polypropylene fibers, carbon fibers and the like), fly ash, slag and the like, but the strength of the filling body is improved by the materials in a limited way, and the using amount of cement cannot be reduced. In addition, other cementing materials are adopted to replace cement to improve the performance of the filling body, but compared with the cement, the performance of the cementing material is not obviously improved, and the cost is still higher. Therefore, the existing filling body proportioning technology needs to be innovated, the performance of the filling body is improved, and the requirement of deep mining on the strength of the filling material is met.

Disclosure of Invention

The invention provides a preparation method of nano-cellulose reinforced filling slurry, aiming at the problems of high requirement on a filling body in a deep mining environment, high filling difficulty, high investment of filling facilities, difficult quality guarantee and the like, the preparation method can greatly enhance the water retention property, the workability and the yield stress of the filling slurry, the formed filling body has high strength and compact structure, and the unit consumption of cement is reduced and the filling cost is reduced under the condition of meeting the strength requirement.

The method comprises the following steps:

s1: mixing the nano cellulose dry powder and sodium carboxymethylcellulose (CMC) powder in a stirring bin, uniformly stirring by a machine, and simultaneously carrying out ultraviolet irradiation treatment;

s2: transferring the uniformly mixed mixture in the S1 to a belt conveyor through the bottom of a stirring bin, conveying the mixture to a feeder, and uniformly placing ultraviolet light generating equipment at the two sides of the belt conveyor at intervals of 1-2 m for ultraviolet light irradiation;

s3: after the mixture is sent to the feeder by the belt conveyer, the mixture is added into the filling slurry stirring bin one by one, and high-speed stirring is kept in the adding process to ensure uniform stirring; and after the slurry is uniformly stirred, pumping the filling slurry to an underground goaf through a pipeline for filling construction.

Wherein the nano-cellulose dry powder in S1 is cellulose nano-fiber (CNF) or nano-cellulose crystal (CNC) prepared by acidolysis, oxidation or high-pressure homogenization, and has a particle size of 30-100 nm.

The dosage of the nano-cellulose dry powder in the S1 is 0.01-1% of the mass of the cement in the filling slurry in the S3.

The using amount of the sodium carboxymethyl cellulose powder in the S1 is 0.2-1% of the mass of the cement in the filling slurry in the S3.

And in the S1, a magnetic stirrer or an overhead stirrer is adopted for mechanical stirring of the stirring bin, the stirring speed is 50-100 r/min, and the continuous stirring time is 1-2 h.

Ultraviolet light is generated by a high-pressure mercury lamp, the pressure of mercury vapor is 105-106 kPa, the wavelength is 300-400 nm, and continuous irradiation is carried out.

The filling slurry in the S3 comprises cement, tailings and water, wherein the cement is 425R ordinary portland cement, the mass ratio of the cement to the tailings is 1: 4-1: 12, and the concentration of the filling slurry is 65-70%.

In the process of mixing and stirring the filling slurry in the S3, the stirring speed is not lower than 10r/min, and the stirring time is not lower than 1 h.

And S3, adding the mixture into the filling slurry stirring bin one by one, wherein the adding amount is 1/5-1/4 of the total amount of the mixture each time until the adding is finished.

And (8) after the filling slurry is uniformly stirred in the step (S3), conveying the slurry to a goaf to be filled by a high-pressure pump.

The technical scheme of the invention has the following beneficial effects:

in the scheme, the nano-cellulose and the carboxymethyl cellulose are compounded and applied to the underground cemented filling material, so that the physical and mechanical properties of the filling material can be greatly enhanced. The nano cellulose has the advantages of high strength, light weight, small particles and large specific surface area, and after being mixed with the filling slurry, the nano cellulose particles are attached to the peripheries of cement particles and tailing particles and are prevented from being aggregated with each other, so that the hydration degree of the slurry can be greatly improved, and the strength of a filling body is improved. The carboxymethyl cellulose can effectively improve the dispersibility of the nano cellulose and the action effect, has high viscosity and strong adhesiveness, can accelerate tailing flocculation, improve the slurry concentration, enable the structure of the filling body to be more compact, improve the compressive strength, the water resistance and the corrosion resistance of the filling body, reduce the cement consumption and achieve the aim of further reducing the filling cost.

Drawings

FIG. 1 is a process flow diagram of a method of preparing a nano-cellulose reinforced filler slurry according to the present invention;

FIG. 2 is a graph showing the variation of compressive strength of different ages of the prepared filler test block with CNF content according to the embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The invention provides a preparation method of nano-cellulose reinforced filling slurry.

As shown in fig. 1, the method comprises the steps of:

s1: mixing the nano cellulose dry powder and the sodium carboxymethyl cellulose powder in a stirring bin, uniformly stirring by a machine, and simultaneously carrying out ultraviolet irradiation treatment;

s2: transferring the uniformly mixed mixture in the S1 to a belt conveyor through the bottom of the stirring bin, conveying the mixture to a feeder, and uniformly placing ultraviolet light generating equipment on two sides of the belt conveyor for ultraviolet light irradiation;

The following description is given with reference to specific examples.

The embodiment of the invention uses the following main raw materials: cellulose Nanofiber (CNF) with the particle size of 30-80 nm is prepared into powder by a sulfuric acid method; sodium carboxymethylcellulose (CMC) is a white powdery solid, a commercially available product. Ordinary portland cement, reference 425R; the tailings are taken from certain gold ores in China, and the average grain size is 120-200 mu m.

According to the cement: the two were mixed at a ratio of 1:6, and normal tap water was added to prepare a 68% slurry.

Powdery CMC accounting for 0.3 percent of the mass of the cement is respectively mixed and stirred with powdery CNF accounting for 0, 0.02 percent, 0.04 percent, 0.08 percent, 0.16 percent, 0.32 percent, 1 percent and 2 percent of the mass of the cement, and a magnetic stirrer is adopted to stir for 2 hours at the rotating speed of 100 r/min. And in the stirring process, continuously irradiating by using ultraviolet light generated by a high-pressure mercury lamp, flattening the mixed material after stirring is finished, and continuously irradiating for 1 hour by using the ultraviolet light.

And (3) placing the prepared filling slurry in a stirring bin, starting a stirrer at a speed of 10r/min, adding the mixture of the CMC and the CNF into the filling slurry in several times, wherein the adding position is a vortex center formed by a stirring blade, and adding the mixture for the next time after the added powder disappears. The stirring mode is continuous stirring.

And (3) casting and molding the obtained CMC-CNF reinforced filling slurry material in a mold with the diameter of 50 mm multiplied by 100mm, and curing in a standard curing box.

And curing the filler test pieces under different conditions for 3d, 7d and 28 days, and measuring the uniaxial compressive strength of each group of test pieces.

FIG. 2 is a graph showing the variation of the compressive strength of the filling mass prepared in this example at different ages according to the CNF content.

As can be seen from the graph, the strength of each age of the filler test piece with different CNF contents shows a trend of increasing first and then decreasing along with the increase of the content. When the content of CNF is lower than 1%, the strength enhancement effect on the filling body is continuously increased, mainly because the CNF particles are nano-scale and large in specific surface area, and can be uniformly distributed in the filling body slurry to wrap cement and tailing particles, so that the aggregation of the cement and tailing particles is avoided, the hydration is more sufficient, the structure of the filling body is more compact, the strength is higher, in addition, the ultraviolet treatment can promote the graft copolymerization modification of the CNF particles, and the dispersibility is improved, meanwhile, the sodium carboxymethyl cellulose particles are anionic cellulose ether and can be adsorbed outside the CNF particles, the dispersibility is improved, meanwhile, the sodium carboxymethyl cellulose can improve the yield stress of the filling slurry, the water retention property is improved, the good workability is kept, and the improvement of the strength of the filling body is also promoted to a certain extent.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. a preparation method of nanocellulose reinforced filler slurry, is characterized in that, comprises the steps as follows:

S1: Mix the nanocellulose dry powder and the sodium carboxymethyl cellulose powder in a stirring bin, stir uniformly by mechanical stirring, and perform ultraviolet light irradiation treatment at the same time;

S2: The uniformly mixed mixture in S1 is transferred to the belt conveyor through the bottom of the mixing bin and transported to the feeder. The ultraviolet light generating equipment is evenly placed on both sides of the belt conveyor at an interval of 1m to 2m for ultraviolet light irradiation;

S3: After the belt conveyor sends the mixture to the feeder, it is added to the filling slurry mixing bin one by one. During the adding process, high-speed stirring is maintained to ensure uniform mixing; Goaf filling construction.

2. the preparation method of nanocellulose reinforced filling slurry according to claim 1, is characterized in that, in described S1, nanocellulose dry powder is the cellulose nanofiber prepared through acidolysis method, oxidation method or high pressure homogenization method Or nanocellulose crystals with a particle size ranging from 30 to 100 nm.

3 . The preparation method of nanocellulose reinforced filler slurry according to claim 1 , wherein the amount of nanocellulose dry powder in S1 is 0.01% to 1% of the cement quality in the filler slurry in S3 . 4 .

4. The preparation method of nanocellulose reinforced filler slurry according to claim 1, characterized in that, the amount of sodium carboxymethyl cellulose powder in S1 is 0.2%～0.2% of the cement quality in the filler slurry in S3 1%.

5. the preparation method of nanocellulose reinforced filling slurry according to claim 1, it is characterized in that, in described S1, the mechanical stirring of stirring chamber adopts magnetic stirrer or overhead stirrer, and stirring rate is 50～100r/min , continuous stirring time 1 ~ 2h.

6 . The preparation method of nanocellulose reinforced filling slurry according to claim 1 , wherein the ultraviolet light is generated by a high-pressure mercury lamp, the mercury vapor pressure is 105-106 kPa, the wavelength is 300-400 nm, and the irradiation is continued. 7 .

7. the preparation method of nanocellulose reinforced filler slurry according to claim 1, is characterized in that, among the described S3, filler slurry comprises cement, tailings and water, and cement is 425R ordinary Portland cement, and cement and The mass ratio of tailings is 1:4 to 1:12, and the filling slurry concentration is 65% to 70%.

8. The preparation method of nanocellulose reinforced filling slurry according to claim 1, characterized in that, during the mixing and stirring process of the filling slurry in the S3, the stirring rate is not less than 10r/min, and the stirring time is not less than 10 r/min. 1h.

9. the preparation method of nanocellulose reinforced filling slurry according to claim 1, it is characterized in that, in described S3, add mixture successively in filling slurry stirring bin, and each addition is the total amount of mixture. 1/5 to 1/4 until the addition is complete.