Influencing Factors on Strength of Waste Rock Tailing Cemented Backfill

Tailing cement filling is an important development direction in mine filling, as it is a green and environmentally friendly method for efficiently treating solid waste in mines. Adding a certain amount of waste rock can effectively improve the backfill strength and better meet the filling strength requirements. To address the use of waste rock tailings in cemented filling materials, a uniaxial compression test was carried out on backfills with different cement/sand ratios and waste rock contents, and the influence of the cement/sand ratio and waste rock content on the strength of the backfill was studied. This study found that when the waste rock content is certain, the strength of the backfill increases with the increase in the cement/sand ratio, and the increase in strength slows with the increase in the cement/sand ratio until the strength of the backfill reaches a limit and no longer increases. When the cement/sand ratio is constant, the strength of the backfill first increases and then decreases as the waste rock content increases. When the cement content is constant, the addition of a certain amount of waste rock reduces the specific surface area of the solid materials in the backfill, increases the amount of cement per unit area, and improves the strength of the backfill. When the waste rock content is too high, due to the large particle size of the waste rock, the tailings cannot completely wrap around the waste rock, resulting in a weakening of the cement in the backfill, which reduces the strength of the backfill. This study found that the waste rock content and the cement/sand ratio in the backfill have a significant impact on backfill damage. The damage is mainly caused by insufficient cement strength. The presence of waste rock will change the original direction of crack propagation, resulting in more crack bifurcation, and the form of the destruction surface on the backfill is complicated and diverse.

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ANALYSIS AND EVALUATION OF FORMATION SCHEMES OF A COMBINED ARTIFICIAL ARRAY FOR THE STORAGE-CHAMBER DEVELOPMENT SYSTEM

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2020-12-3-436-443 ◽

2020 ◽

Vol 12 (3) ◽

pp. 436-443

Author(s):

Azamat ALLABERDIN ◽

◽

Artur MAZHITOV ◽

Ivan PYTALEV ◽

Sergej GAVRISHEV ◽

...

Keyword(s):

Ore Deposits ◽

Economic Feasibility ◽

Waste Rock ◽

Expert Assessment ◽

Development System ◽

Filling Materials ◽

Storage Chamber ◽

Radical Reduction ◽

Dump Trucks ◽

The Cost

The aim of the study is to optimize technological solutions to reduce the cost of building a filling array, which remains one of the most pressing issues in the development of ore deposits by underground method. To achieve this goal, a comprehensive research method is used, which includes, first of all, a generalization and analysis of the practice of backfilling of enterprises, geotechnological design in relation to the storey-chamber development system and a feasibility study of optimization solutions at the level of expert assessment using the capabilities of engineering forecasting. Laying works with underground technology of mining of mineral deposits are the most costly, in connection with which research is carried out in order to develop ways to reduce the cost of repayment of the worked-out area. Through a systematic review and critical analysis of existing backfill technologies, the technical feasibility and economic feasibility of combining a hardening mixture and waste rock within a single repayable object has been identified, which provides a radical reduction in the proportion of hardening backfill. In the article offered to the reader’s attention, a variant of the combined array design and the technology of its formation are proposed. A variant of mechanization of the process of erection of the combined massif using specialized dump trucks is provided. This method of forming a combined filling mass allows reducing the volume of the hardening mixture in the total volume of the worked out space of the chambers by not a third. In connection with the complex mechanism of the formation of the combined filling massif, the work considers various options for the discharge of rock into the goaf, which differ in the number of points of discharge of the ingredients of filling materials into the goaf. Based on geotechnological design and mathematical modeling of the formation of a filling massif, it is certain that to increase the efficiency of filling the worked-out chamber space, two points of controlled rock discharge are necessary. The study identified ways to reduce the cost of controlling rock pressure in specific conditions by combining hardening mixture and waste rock for filling voids with a reduction in the proportion of hardening filling up to 50%. A variant of the combined massif construction with mechanization of the massif erection process using specialized dump trucks can significantly reduce the volume of the hardening mixture.

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Study on the strength property and ratio parameter selection of waste rock cemented backfill

JOURNAL OF MINING ENGINEERING AND RESEARCH ◽

10.35624/jminer2020.01.02 ◽

2021 ◽

Vol 2 (1) ◽

pp. 7-13

Author(s):

Xiaoming Wei ◽

Lijie Guo ◽

Lei Zhang

Keyword(s):

Flow Property ◽

Waste Rock ◽

Parameter Determination ◽

Slurry Concentration ◽

Strength Change ◽

Cemented Backfill ◽

Unclassified Tailings ◽

Research Findings ◽

Slurry Stability

When tailings are used for cemented backfill preparation, the extremely fine unclassified tailings may lead to slow consolidation and low strength of backfill material. Wasted rock as an additional filling aggregated was suggested to optimize the gradation composition of aggregate by scholars over the world. In this paper, the effect of waste rock addition, cement-tailing ratio and slurry concentration on strength and flow properties of waste rock cemented backfill were studied. The results indicate the strength of waste rock cemented backfill was significantly higher than that of unclassified tailings cemented backfill under same cement consumption, which the average strength improvements were 2.02MPa, 0.98MPa and 0.46MPa under cement-tailing ratio of 1:4, 1:8 and 1:10. With the increase of waste rock addition, the strength change of waste rock cemented backfill was less obvious, but the flow property (yield stress) of filling slurry was improved. Further analysis of the slurry stability illustrates that, with the increase of waste rock addition, the bleeding rate demonstrated a trend similar to that observed for the flow property, however, in an adverse manner. Overall, the optimal slurry concentration of 80% and waste rock addition of 40%～50% were determined. Based on the strength requirement, cement dosage was selected, which the cement-tailing ratio of top 10m and the bottom 10m was 1:8, the cement-tailing ratio of the centre stope was 1:10. The research findings can provide a reference for the ratio parameter determination of extremely fine unclassified tailings backfill of similar mines.

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Numerical Calculation Analysis of the Structural Stability of Cemented Fill under Different Cement-Sand Ratios and Concentration Conditions

Advances in Civil Engineering ◽

10.1155/2018/1260787 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Kang Zhao ◽

Qiang Li ◽

Yajing Yan ◽

Keping Zhou ◽

Shuijie Gu ◽

...

Keyword(s):

Mechanical Properties ◽

High Efficiency ◽

Structural Characteristics ◽

Key Factors ◽

Principal Stresses ◽

Filling Materials ◽

Cemented Backfill ◽

The Stability ◽

Pillar Structure ◽

Safety And Stability

The effect of lime-sand ratio and slurry concentration on the mechanical properties of backfills is important. To achieve green and high-efficiency mining, accurately determining the optimum ratio of cemented tailings for certain tungsten tailings and ensuring the safety and stability of the mine stope structure are important. The cement-sand ratios used in this research were 1 : 6 and 1 : 8. The mechanical properties were evaluated by using 68%, 72%, and 78% of tailing cemented filling materials. The corresponding physical and mechanical parameters were obtained through uniaxial compression, splitting, and shearing mechanical experiments on the backfill specimens. FLAC3D was used to investigate the mechanical properties of cement-filled pillars and the stability of supporting surrounding rocks on the basis of the mine’s current room pillar structure size parameters and mining sequence. The key factors that affect the stability of the goaf were analyzed by evaluating the plastic zone area of the stope, maximum and minimum principal stresses, and displacement change. The structural characteristics of stope structures and changes of rock mass damage were obtained under different cement-tailing ratios and concentrations. A cemented backfill with a cement-tailing ratio of 1 : 8 and a concentration of 68% was selected as the best solution for the mine in terms of safety and economic considerations.

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Model studies on cemented tailings used in mine backfill

Canadian Geotechnical Journal ◽

10.1139/t82-002 ◽

1982 ◽

Vol 19 (1) ◽

pp. 14-28 ◽

Cited By ~ 44

Author(s):

Robert J. Mitchell ◽

Richard S. Olsen ◽

John D. Smith

Keyword(s):

Blast Hole ◽

Three Dimensional ◽

Model Testing ◽

Scale Model ◽

Mine Backfill ◽

Model Studies ◽

Physical Model Tests ◽

Mining Methods ◽

Backfill Strength ◽

Cement Strength

Physical model tests on cemented classified tailings and sand backfills have been carried out to determine the strength requirements for stability when vertical fill faces are exposed. The results of this laboratory scale model testing support a three-dimensional analytical solution developed in the paper, whereby the cement strength requirement can be reduced when rock walls are sufficiently close together to help support the backfill by shearing stresses at the wall–backfill contact.Comparisons with conventional backfill strength design approaches show that substantial reductions in cement usage can be realized by using the three-dimensional design approach, particularly when blast hole stoping can be carried out to heights several times greater than the lateral stoping dimensions.Physical modelling of cemented backfills is discussed in detail in the paper and it is concluded that field scale model testing could be useful in the design stages of the development of mining methods at individual mines.

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