scholarly journals Effect of Air Entrainment on Cemented Mine Backfill Properties: Analysis Based on Response Surface Methodology

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 81
Author(s):  
Mohammed Hefni ◽  
Ferri Hassani
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Underground Mining ◽  
Air Entrainment ◽  
Silica Sand ◽  
Dry Density ◽  
Mine Backfill ◽  
Study Results ◽  
Potential Benefits ◽  
Entrained Air

As part of an extensive research program exploring the potential benefits of using air-entraining admixtures in mine backfill, the experimental study presented in this paper investigates the effect of cement and entrained air dosages on mine backfill unconfined compressive strength (UCS), fresh density, and dry density. Backfill specimens were prepared using silica sand, normal Portland cement, water, and an entrained air admixture. An experimental design with response surface methodology was adopted to develop predictive mathematical models and analyze the results. The results demonstrated that an entrained air dosage of 3.5% could improve the UCS of the mine backfill owing to better dispersion of cement particles. However, a further increase in the dosage reduced the UCS as well as the fresh and dry densities by approximately 200 and 120 kg/m3, respectively. Study results imply that using air-entraining admixtures can potentially enhance mine backfill flowability and reduce the density, thus providing safer and more sustainable working conditions in an underground mining environment.

scholarly journals Experimental Development of a Novel Mine Backfill Material: Foam Mine Fill

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 564
Author(s):  
Mohammed Hefni ◽  
Ferri Hassani
Keyword(s):  
Mixing Time ◽  
Working Environment ◽  
Dry Density ◽  
Experimental Development ◽  
Hydraulic Fill ◽  
Mine Backfill ◽  
Air Bubble ◽  
Backfill Material ◽  
Bubble Structure ◽  
Entrained Air

This study aims to develop a novel mine backfill material called foam mine fill (FMF). A cellular structure is achieved by incorporating a premade foam into the backfill mixture using an air-entraining agent. FMF samples were prepared with copper-nickel mine tailings and normal Portland cement. Experiments were designed to investigate the effect of binder dosage, volume of entrained air, and foam mixing time on FMF unconfined compressive strength (UCS) and dry density. Moreover, a qualitative microscopic assessment investigated the effect of foam mixing time on air bubble structure. The pore size distribution and porosity of selected samples were investigated through mercury intrusion porosimetry. Relative to reference samples without entrained air, the UCS of FMF samples was 20–50% lower. However, the concomitant lower dry density (by up to 360 kg/m3) could enhance the safety of the underground working environment, especially in underhand cut-and-fill mining where miners and machinery work beneath the backfilled stope, and lower-density fill material would minimize the adverse effects of potential backfill failure. Prolonged foam mixing time led to a significant loss in UCS and total collapse of the air bubble structure. Other potential applications for FMF are areas where there are tailings shortages and as an alternative to hydraulic fill.

scholarly journals APPLICATION OF RESPONSE SURFACE METHODOLOGY (RSM) - REDUCTION OF INDUSTRIAL WASTEWATER CHEMICAL OXYGEN DEMAND

2017 ◽  
Vol 5 ◽  
pp. 1226-1232 ◽  
Author(s):  
Emmanuel Kweinor Tetteh ◽  
Sudesh Rathilal
Keyword(s):  
Response Surface Methodology ◽  
Wastewater Treatment ◽  
Chemical Oxygen Demand ◽  
Response Surface ◽  
Industrial Wastewater ◽  
Oxygen Demand ◽  
Chemical Oxygen Demand Removal ◽  
Oil Refineries ◽  
Study Results ◽  
Input Variables

Industrial waste oil in water from oil refineries and petrochemical processing poses a major environmental concern. Environmental pollution from these wastewaters is increasing and will continue to rise due to a growing demand for petrochemical products and energy. The composition of these industrial wastes varies from location to location as well as with manufacturing processes. In terms of water quality issues, chemical oxygen demand is considered one of the most problematic in oil refinery wastewater treatment. This study applies the response surface methodology to obtain a response model for industrial wastewater treatment. Operating parameters are optimized to enhance the treatment performance. The study, focusing on the effects of input variables for chemical oxygen demand removal, was experimentally carried out using dissolved air floatation jar tests. The experimental matrix incorporated the Box-Behnken design in the response surface methodology. In addition, the procedure evaluated the effect of the input variables and their interactions to obtain the optimum condition for the extent of efficiency. The results show that the chemical oxygen demand removal was sensitive to the effect of the input variables and their interactions. The statistical analysis established that the quadratic model was highly significant with a low probability (< 0.0001), indicating that the correlated regression scattering was unlikely random. The predicted model results corresponded well to the experimental results, with a coefficient of determination close to 1.0. The response surface of the model is presented in three-dimensional plots. These study results show that the addition of a coagulant to remove chemical oxygen demand is effective under acidic conditions when response surface methodology is applied.

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