Experimental Study on the Mechanical Properties of Paste-like Fill Material

The experiments, which include the complete stress-strain curves, triaxial compressive loading history and the main factors affecting the compressive strength of the material, were made to research the mechanical properties of paste-like fill material. The results show that the material still has a relatively high load-bearing capacity after yielding. From the view of the backfill strength, the suitable content of the fine particles in the aggregates is 20%, the curing temperature of backfill slurry is about 20 centigrade degrees or higher. The backfill strength can reach 2.5-3.6 MPa when the binder dosage is 5%-8%. It can meet the needs for mining with backfill.     

东乡铜矿全尾膏体充填材料与充填体强度关系研究

针对东乡铜矿分级尾砂或全尾砂胶结充填体强度不够问题,提出了采用全尾膏体充填,并对充填材料与充填体强度之间的关系进行实验研究,实验结果对矿山充填工作有指导意义.     

利用磷尾矿制备加气混凝土工艺参数的探索研究

通过调整各主要组分掺量、水料比以及料浆温度等工艺参数,系统研究了它们对加气混凝土制品性能的影响,并分析探讨了制品强度发挥的机理。研究表明,利用65%以上的磷尾矿,6%的水泥和0.14%的铝粉,在水料比为0.64,温度为45℃时可制成良好坯体,在蒸压条件下,制品的容重可达600kg/m3左右,抗压强度可达到3.7MPa以上。     

粉煤灰混凝土绝热温升的试验研究

目的 研究不同粉煤灰的掺量和不同水肢比条件下粉煤灰混凝土的绝热温升和胶凝材料水化速率的发展规律．方法 利用混凝土绝热温升仪测试混凝土绝热温升．结果 在水胶比0．53条件下，混凝土的绝热温升值随着粉煤灰掺量的增加而下降；在水胶比0．25条件下。绝热温升值先随着粉煤灰掺量的增加而增大，当掺量达40％以后绝热温升值开始下降。混凝土中胶凝材料的水化速率峰值随粉煤灰掺量增加而下降．结论 粉煤灰混凝土的绝热温升受水胶比和粉煤灰掺量共同影响，低水胶比条件下只有适当增加粉煤灰的掺量才能降低粉煤灰混凝土的绝热温升；高水胶比条件下。粉煤灰混凝土的绝热温升随粉煤灰掺量增加而下降。     

含油污泥的固化与成型机理研究

以含油污泥为研究对象,粉煤灰、黏土、实验室自制液态黏结剂为复合黏结剂进行固化实验,探究不同黏结剂组分掺入量（以质量分数计）对固化块强度的影响,并确定最佳固化剂掺入量。结果表明,在粉煤灰掺入量30%、黏土掺入量10%、液态黏结剂掺入量5%的固化块强度达到最佳;在最佳工艺条件下,固化块的冷强度为2.19 MPa,热强度为2.21 MPa,具有足够的冷强度和热稳定性。利用傅里叶红外光谱（FT?IR）、X射线衍射（XRD）和扫描电子显微镜(SEM)等技术手段研究固化块的成型机理,并根据表征结果提出固化块成型机理。     

基于可靠度理论的下向进路充填体强度确定方法

充填体强度确定是制约胶结充填采矿技术发展的三大充填体力学问题之一．阐述了采用传统方法确定充填体强度的不足，结合下向进路力学分析结果，提出了基于可靠度理论的下向进路充填体强度确定方法和随机参数敏感性分析方法．并结合某矿山现场实际，探讨了下向进路承栽层稳定性可靠概率的合理取值，认为承载层稳定性可靠概率为90％时可以满足现场生产的需要．分别采用蒙特卡洛法、改进的JC法和JC法计算了该矿山废石料充填进路承栽层所需的强度值，分析了各随机参数对承栽层稳定性可靠概率影响的敏感性，探讨了承载层稳定性可靠指标与安全系数之间的关系．所提出的方法对阶段充填采矿法充填体强度确定也具有良好的适用性．     

Cemented backfill technology based on phosphorous gypsum

Physical-chemical properties of phosphorous gypsum, proportion and cemented mechanism of slurry with gypsum as aggregate were studied to remove the harms of gypsum pile, combining with difficult problems of excessive mined-out gobs, enormous ore body under roadway and low recovery ratio of Yongshaba Mine, Kaiyang Phosphor Mine Group, Guizhou Province, China. An appropriate backfill system and craftwork were designed, using shattering milling method to crush gypsum, double-axles mixing and strong activation mixing way to mix slurry, cemented slurry and mullock backfill alternately process. The results show that gypsum is fit for backfilling afterwards by adding fly ash, though it is not an ideal aggregate for fine granule and coagulate retardation. The suggested dosage (the mass ratio of cement to fly ash to gypsum) is 1:1:6–1:1:8 with mass fraction of solid materials 60%–63%. Slurry is transported in suspend state with non-plastic strength, and then in concretion state after backfilling. The application to mine shows the technology is feasible, and gypsum utilization ratio is up to 100%. Transportation and backfill effect is very good for paste-like slurry and drenching cemented slurry into mullock, and the compressive strength and recovery ratio are 2.0 MPa and 82.6%, respectively, with the maximum subsidence of surface only 1.307 mm. Furthermore, the investment of system is about 7×10⁶ yuan (RMB), only 1/10 of that of traditional paste backfill system. Foundation item: Project (2006BAB02A03) supported by the National Key Technology Research and Development Program; Project (08MX16) supported by Mittal Scientific and Technological Innovation Projects of Central South University during 2008     

矿用充填胶凝材料激发剂配比智能优化决策

针对矿用充填胶凝材料不同配比的激发剂化学复合作用所引起充填胶结体单轴抗压强度复杂非线性变化问题,提出一种充填胶凝材料激发剂配比智能优化决策方法.首先,开展均匀设计试验获取不同激发剂配比充填胶结体抗压强度数值;其次,采用动态自适应交换变异概率及适应度竞争交换方式的改进遗传树表征激发剂与充填胶结体抗压强度之间的非线性复杂关系,运算至49代时即满足终止法则,收敛速度较快,函数精度高;最后,确定约束条件,建立激发剂配比优化模型,采用遗传算法的全局快速寻优技术,获得满足充填体强度要求的激发剂优化配比.结果表明:采用该智能优化方法研究铁矿新型充填胶凝材料激发剂配比,优化结果显示,满足该矿山充填体强度的胶凝材料优化配比为生石灰2.91%、石膏17.39%、矿渣粉79.7%;在该优化配比周围开展验证试验,试验结果显示为生石灰3%、石膏17%、矿渣粉80%时、充填体7、28d抗压强度均达到最大,与激发剂配比智能优化方法获得的胶凝材料配比相吻合.相比42.5水泥,用该智能优化方法获得的激发剂配比制备全尾砂充填胶凝材料,可降低材料成本22%.     

Effects of water content,water type and temperature on the rheological behaviour of slag-cement and fly ash-cement paste backfill

The pumping ability and placement performance of fresh cemented paste backfill(CPB) in underground mined cavities depend on its rheological properties. Hence, it is crucial to understand the rheology of fresh CPB slurry, which is related to CPB mixture design and the temperature underground. This paper presented an experimental study investigating the effects of binder type, content, water chemical properties and content, and temperature, on the rheological properties of CPB material prepared using the tailings of a copper mine in South Australia. Portland cement(PC), a newly released commercially manufactured cement called Minecem(MC) and fly ash(FA) were used as the binders added to the mine tailing materials. Various amounts of two different water types were added to the mixtures in the preparation of backfill material slurry. Six different temperatures ranging from 5 to 60 °C were to investigate the effect of temperature on CPB rheology. Overall, the increasing water content and decreasing temperature lead to lower yield stress. Based on the results obtained from the rheological properties of CPB slurry, it was found that at room temperature(25 °C), with regards to the unconfined compressive strength(UCS) performance, the replacement of 4% PC mixed CPB(28 days UCS 425 k Pa) to 3% MC mixed CPB(28 days UCS 519 k Pa), reduced the slurry yield stress from 210.7 to 178.5 Pa. The results also showed that the chemical composition of water affects the yield stress of CPB slurry and that MC mitigates the negative effect of mine-processed water(MW) and thus lead to improve the rheological properties of the slurry. However, the results suggested that the rheological properties of a mixture using MC is very sensitive to the water volume and temperature change. Therefore, using MC in backfill requires better quality control in slump mixing.     

Hydration Characteristics and Humidity Control Performance of Calcium Silicate Board Prepared from Mine Tailing and Diatomite

The feasibility of utilizing molybdenum tailing and diatomite as siliceous materials to prepare calcium silicate board was explored. The influences of molybdenum tailing/diatomite proportion on hydration characteristics, thermal conductivity, water absorption, flexural strength and moisture adsorption-desorption property of calcium silicate board were investigated in detail. The experimental results reveal that molybdenum tailing is environmentally friendly to prepare building materials. The main hydration products in calcium silicate board under autoclaved condition are C-S-H with low crystallinity and tobermorite. Molybdenum tailing is favorable to the formation of tobermorite. The flexural strength and bulk density of the calcium silicate board gradually increase when the content of molybdenum tailing increases. Netlike C-S-H is formed with the increase of diatomite content during autoclaved curing process, resulting in the enhancement of moisture adsorptiondesorption performance and the reduction of thermal conductivity. The optimal content of molybdenum tailing is 20%, furthermore, the flexual strength and thermal conductivity of calcium silicate board at this content meet the Chinese standard JC/T564.1-2008.     

尾砂的火山灰活性及其快速检测方法研究

针对传统方法测定尾砂火山灰活性周期很长的问题，提出了一种快速检测方法，用该方法每测定一个样品只需４ｈ，实验结果表明，对于取自不同矿山的尾砂，其活性大小相差很大，该方法所测定的尾砂活性大小与固结体２８ｄ抗压强度有相关性。     

Mechanical analysis of roof stability under nonlinear compaction of solid backfill body

Based on the compaction characteristic test and the nonlinear compaction deformation characteristics of backfill material, this paper applies the theory of nonlinear elastic foundation of thin plate to establish a mechanical model of backfill body and roof in solid dense backfill coal mining. This study critically analyses the deflection equation of the roof by the energy method, derives the conditions of roof breakage and combined with concrete engineering practice analyses, determines roof movement regularity and stability in solid dense backfill mining. Analysis of the engineering practice of the 13,120 backfill panel of Pingmei 12# mine shows the theoretical maximum of roof convergence in backfill mining to be415 mm which is in significant agreement with the measured value. During the advancing process of solid backfill mining at the panel, the maximum tensile stress on the roof is less than its tensile strength which does not satisfy the conditions for roof breakage. Drilling results on the roof and ground pressure monitoring show that the integrity of roof is strong, which is consistent with the theoretical calculations described in this study. The results presented in the study provide a basis for further investigation into strata movement theory in solid dense backfill mining.     

生态纤维混凝土的收缩性能试验研究

高性能混凝土低水胶比和掺加矿物掺合料的特点使得混凝土收缩加剧并且引起早期裂缝问题.采用粉煤灰和硅灰作为纤维混凝土的掺合料,通过混凝土配合比的正交试验,利用极差和方差分析,研究了水胶比、砂率、硅灰掺量、生态纤维掺量和粉煤灰掺量对混凝土7,28 d抗压强度的影响.分析了粉煤灰采用超量取代的方法对混凝土的影响.在保证混凝土抗压强度的基础上,优选混凝土配合比,进行混凝土干燥收缩试验.试验结果表明,生态纤维对混凝土强度影响不明显,与矿物掺合料复掺可显著抑制混凝土的干燥收缩.     

磷石膏二灰基层材料配合比设计方法研究

通过系列的配合比试验，结合改性二灰基层材料的强度形成原理，建立了一套以体积分析法为基础的配合比设计方法。这种设计方法包括磷石膏改性二灰路面基层材料的结合料集料配比、石灰掺量、磷石膏掺量、粉煤灰掺量的设计以及干密度含水量等参数的确定。研究表明：按集料松堆密度计算的结合料集料比的骨架密实型路面基层材料具有较好的性能，用该方法计算的配合比与击实参数和实际值十分吻合，完全可以满足磷石膏改性二灰和二灰基层的材料设计与生产控制。     

Numerical investigation into the effect of backfilling on coal pillar strength in highwall mining

This paper attempts to quantify the effect of backfilling on pillar strength in highwall mining using numerical modelling. Calibration against the new empirical strength formula for highwall mining was conducted to obtain the material parameters used in the numerical modelling. With the obtained coal strength parameters, three sets of backfill properties were investigated. The results reveal that the behavior of pillars varies with the type and amount of backfill as well as the pillar width to mining height ratio(w/h). In case of cohesive backfill, generally 75% backfill shows a significant increase in peak strength, and the increase in peak strength is more pronounced for the pillars having lower w/h ratios. In case of noncohesive backfill, the changes in both the peak and residual strengths with up to 92% backfill are negligible while the residual strength constantly increases after reaching the peak strength only when 100%backfill is placed. Based on the modelling results, different backfilling strategies should be considered on a case by case basis depending on the type of backfill available and desired pillar dimension.     

大孔生态混凝土强度与抗硫酸盐侵蚀性能

为了降低成本和提高抗硫酸盐侵蚀性能,按总胶凝材料用量30%的取代量掺入粉煤灰和矿粉,通过调整细骨料用量来控制大孔混凝土的孔隙率,分别制备了孔隙率为15%、20%和25%的粉煤灰系列和矿粉系列大孔生态混凝土.研究了胶凝材料用量、水胶比和孔隙率对大孔生态混凝土抗压强度和抗硫酸盐侵蚀性能的影响规律.结果表明:大孔混凝土的强度随着胶凝材料用量的增加、水胶比的减小和孔隙率的降低呈线性缓慢地增大;大孔生态混凝土的硫酸盐侵蚀作用在内外同时发生,其抗硫酸盐侵蚀能力明显低于普通混凝土,但当矿物掺合料用量达胶凝材料总量30%时,60次干湿循环后的抗侵蚀系数大于100%.     

150 MPa超高强水泥基材料的研究

采用常规原材料和工业废渣，普通成型工艺，通过正交设计试验研究，配制出了抗压强度为150MPa的超高强水泥基材料，并给出了优选配比。超高强水泥基材料强度试验的极差和方差分析表明：水胶比为影响超高强水泥基材料强度的最显著因素，硅灰和不锈钢纤维渣的掺量以及胶砂比也有十分显著的影响。     

石灰粉煤灰稳定铁尾矿碎石的路用性能研究

根据《公路无机结合料稳定材料试验规程》的相关试验方法,对石灰粉煤灰稳定铁尾矿碎石混合料的强度、模量、抗冻性能、水稳定性等路用技术性能进行了系统的试验研究,分析了其强度的影响因素,并阐述了石灰粉煤灰稳定铁尾矿碎石的强度形成机理。试验结果表明,石灰粉煤灰稳定铁尾矿碎石的各项技术性能满足现行规范的要求,可以作为各级公路的底基层或基层材料。     

Valorization of mining waste and tailings through paste backfilling solution,Imiter operation,Morocco

Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally stored on surface areas. The volume and chemical characteristics of these materials generate serious problem for required storage spaces and mainly environmental degradation. Paste backfill(PBF) is one of ingenious solutions to minimize the quantity of tailings to store. PBF is basically defined as a combination of mine processing tailings, binder, and water mixing. The purpose of this paper is to present backfilling components characterization and formula verification for a waste valorization solution through paste backfilling technology in Imiter operation. Obtained results and realized analysis demonstrate PBF conformity and adequacy with assigned underground functions. However the studied recipe can be more ameliorated to obtain an optimal mixture ensuring the required mechanical strength.     

MECHANICAL PROPERTIES AND MICROSTRUCTURE OF COMPOSITE BINDERS CONTAINING SHALE ASH AND FLY ASH

The microstructure and the mechanical properties of hardened mortars made of superplasticized composite binder containing shale ash and fly ash are investigated. The pozzolanic reaction consumes the oriented Ca (OH)2 crystals, thus making the transition zone dense. Appropriately proportioning of shale ash and fly ash decreases the water requirement and increases the packing density of composite binder mortars, therefore increases their strength. Super plasticizer promotes the carbonation of calcium hydrates and the formation of ettringite that is transformed gradually into mono-sulfoaluminate hydrate in composite binder mortars. The joint action of fine complex mineral admixture and super plasticizer has a synergistic effect to improve the mechanical properties of composite binder.