Non-explosive mining and waste utilization for achieving green mining in underground hard rock mine in China

Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases inevitably.Cuttability of deep hard rock was investigated by experimental and regressed analyses to find the reasonable stress adjustment method to improve non-explosive mechanized fragmentation for hard ore-rock.A non-explosive mechanized and intellectualized mining method was proposed to continuously and precisely exploit phosphate underground,which promoted the high-recovery,low-waste and high-efficiency exploitation of phosphate with recovery rate over 90%,dilution rate near 5%and cutting efficiency about 107.7 t/h.A circular economy model and the backfill system were proposed to conduct resource utilizations of solid waste,by which the utilization amount of waste increased year after year.In 2018,the utilization amounts of phosphogypsum,yellow phosphorus slag and waste rock increased to 1853.6×10^3 t/a,291.1×10^3 t/a and 1493.8×10^3 t/a,respectively.

Field application of non-blasting mechanized mining using high-frequency impact hammer in deep hard rock mine

A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.

Improving performance of Cs_(2)AgBiBr_(6)solar cell through constructing gradient energy level with deep-level hole transport material

The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite solar cell(PSC)for achieving high power conversion efficiency(PCE).To tackle this problem,we propose the optimization of the energy level alignment by designing and synthesizing novel deep-level hole transport materials(HTMs).The sole introduction of deep-level HTMs successfully reduces the valence band offset between Cs_(2)Ag Bi Br_(6)and HTL,but induces the increased valence band offset at HTL/Au interface,limiting the PCE improvement.To further solve the problem and improve the PCE,the gradient energy level arrangement is constructed by combining the newly developed deep-level HTM 6,6’-(3-((9,9-dimethyl-9H-fluoren-3-yl)(4-methoxyphenyl)amino)thiophene-2,5-diyl)bis(N-(9,9-dimethyl-9H-fluoren-2-yl)-N,9-bis(4-methoxyphenyl)-9H-carbazol-3-amine)(TF)with 2,2’,7,7’-tetrakis(N,N’-dipmethoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD).Through optimization,an impressive PCE of 3.50%with remarkably high open-circuit voltage(V_(oc))and fill factor(FF)is achieved,qualifying it among the best pristine Cs_(2)AgBiBr_(6)PSCs.