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Gold Science and Technology >

2021 , Vol. 29 >Issue 2: 218 - 225

DOI: https://doi.org/10.11872/j.issn.1005-2518.2021.02.119

Mining Technology and Mine Management

Analysis of Acoustic Emission Index Characteristics for Indoor Uniaxial Com-pression Test of Backfill

  • Rong LU , 1, 2, 3 ,
  • Fengshan MA , 1, 2 ,
  • Jie ZHAO 3 ,
  • Jie GUO 1, 2 ,
  • Jinzhong GU 4 ,
  • Yeqiang HUANG 4
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  • 1. Key Laboratory of Shale Gas and Geoengineering，Institute of Geology and Geophysics，Chinese Academy of Sciences，Beijing 100029，China
  • 2. Innovation Academy for Earth Science，Chinese Academy of Sciences，Beijing 100029，China
  • 3. Deep Mining Laboratory of Shandong Gold Group Co. ，Ltd. ，Laizhou 261400，Shandong，China
  • 4. Jinchuan Group Co. ，Ltd. ，Jinchang 737100，Gansu，China

Received date: 2020-07-06

  Revised date: 2020-11-18

  Online published: 2021-05-28

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Highlights

As the shallow mineral resources exhausted，deep mining is the general trend for global mining engineering. Backfill method is widely used in metal mining engineering which control the mine stability. With the improvement of the method，the mechanical behavior of backfill is attracted extensive attention. This article analyzed backfill mechanical behavior based on the experimental test.Combined uniaxial compression tests with acoustic emission monitoring，backfill samples with pre-existing crack were tested.Five groups backfill samples were tested and all samples with strength within 35 MPa. Five groups sample with dips of 0°，30°，45°，60°，and 90°，represented five fractures distribution.The results show that backfill sample with 90°-dip fracture demonstrated more obvious brittleness and less plasticity than other samples.Acoustic emission signals could represent fractures initiation and development of backfill samples.Acoustic emission locations have their characteristics in five groups backfill samples. Initially，acoustic emission of backfill sample with 0°-dip fracture located near the pre-existing fracture，and then develop to the other parts of sample.While for backfill samples with other four dips fractures，acoustic emission mainly concentrated near the pre-existing fractures from initial stage to failure.For acoustic emission monitoring，some parameters could demonstrate the me-chanism of fractures propagation.In this article，three parameters were analyzed，they are AF，RA，and lg（AF/RA），respectively. AF represented the tensile fracture propagation，RA represented the shear fracture propagation，and lg（AF/RA） could reveal the overall fracture development.The process of backfill compression is divided into eight stages，namely crack closure，line elastic deformation，micro-crack initiation，stable micro-crack growth，micro-crack coalescence，unstable micro-crack growth，macro-crack coalescence，and failure. Finally，the results show that the dip of pre-existing crack has large influence to backfill deformation and failure according to these three parameter analysis. AE value of the backfill sample with 0°-dip fracture is high in whole deformation process，and RA value remains low and waves in small range. The change of AE and RA value showes shear and rupture in particles is not obvious，and initialed and developed fractures are major tensile.Based on this parameters changed，other four samples parameters values were analyzed，and backfill samples with 30°-dip and 45°-dip fracture are similar to backfill sample with 0°-dip fracture，and backfill samples with 60°-dip and 90°-dip fracture are different.Finally the research come to a conclusion that samples with small dips of pre-existing crack failed by tensile cracks，and samples with large dips of pre-existing crack failed by tensile-shear cracks.

Cite this article

Rong LU , Fengshan MA , Jie ZHAO , Jie GUO , Jinzhong GU , Yeqiang HUANG . Analysis of Acoustic Emission Index Characteristics for Indoor Uniaxial Com-pression Test of Backfill[J]. Gold Science and Technology, 2021 , 29(2) : 218 -225 . DOI: 10.11872/j.issn.1005-2518.2021.02.119

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加拿大矿业协会敦促政府切实重视关键矿产

据Mining Weekly报道，加拿大矿业协会（MCA，Mining Association of Canada）对政府2021年联邦预算中提出的巩固和发展国内电池供应链的几项补充和细化措施表示欢迎，不过会长皮埃尔·格拉顿（Pierre Gratton）认为针对稀土的特殊支持措施力度不大。

4月19日，加拿大财政部长克里斯蒂亚·弗里兰（Chrystia Freeland）在预算报告中提出，为巩固国内电池电动车（BEV）供应链，将战略创新基金（SIF，Strategic Innovation Fund）—净零加速器（Net Zero Accelerator）规模扩大到80亿加元，另外还辅助一些税收激励政策。

“我们需要电池级镍、钴、锂和石墨，能够有这些弥补和扩大国内材料生产的计划和税收措施，令人欣慰。”格拉顿表示。成立关键矿产创新中心（CMCE，Critical Minerals Centre of Excellence）来协调联邦政策和计划，联邦政府3年内投入3 680万加元用于研发，推进关键电池矿产加工和精炼，这些针对稀土的特殊支持措施是正面的，但力度不够。

被列入关键矿产目录的稀土广泛应用于医疗、国防、清洁能源和通信行业。为提高系统供应链韧性，加拿大与美国签署合作行动协议，目的是构建稀土和永磁所需原材料的开采、加工和生产供应链，提升大北美区在这方面的韧性和独立性。

“加拿大具备成为全球领先者的潜力，能够以全面环境友好的方式实现关键矿产自给，并满足伙伴国对关键矿产不断增长的需求”。“尽管2021年预算中包括的支持措施表明支撑构建电池供应链，包括支撑电池生产的矿物和金属，但是如果我们要与美国建立同等和可信赖的伙伴关系来构建北美地区国内供应链，仍然需要采取特殊措施来推动加拿大稀土开发”，格拉顿表示。

2020年，MCA宣布了珠算数据（Abacus Data）完成的一项全国民意调查结果，公众热切希望加拿大发挥资源丰富和环境标准领先的优势扩大在全球关键矿产供应国中的地位。90%的被调查者认为加拿大将成为关键矿产来源的优先选择，政府将采取一系列步骤来支持这项措施。

http://www.goldsci.ac.cn/article/2021/1005-2518/1005-2518-2021-29-2-218.shtml

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