Comparing the reinforcement capacity of welded steel mesh and a thin spray-on liner using large scale laboratory tests

Steel mesh is used as a passive skin confinement medium to supplement the active support provided by rock bolts for roof and rib control in underground coal mines. Thin spray-on liners(TSL) are believed to have the potential to take the place of steel mesh as the skin confinement medium in underground mines.To confirm this belief, large scale laboratory experiments were conducted to compare the behaviour of welded steel mesh and a TSL, when used in conjunction with rock bolts, in reinforcing strata with weak bedding planes and strata prone to guttering, two common rock conditions which exist in coal mines. It was found that while the peak load taken by the simulated rock mass with weak bedding planes acting as the control sample(no skin confinement) was 2494 kN, the corresponding value of the sample with 5 mm thick TSL reinforcement reached 2856 kN. The peak load of the steel mesh reinforced sample was only2321 kN, but this was attributed to the fact that one of the rock bolts broke during the test. The TSL reinforced sample had a similar post-yield behaviour as the steel mesh reinforced one. The results of the large scale guttering test indicated that a TSL is better than steel mesh in restricting rock movement and thus inhibiting the formation of gutters in the roof.

Electrochemical Water Splitting:Bridging the Gaps Between Fundamental Research and Industrial Applications

Electrochemical water splitting represents one of the most promising technologies to produce green hydrogen,which can help to realize the goal of achieving carbon neutrality.While substantial efforts on a laboratory scale have been made for understanding fundamental catalysis and developing high-performance electrocatalysts for the two half-reactions involved in water electrocatalysis,much less attention has been paid to doing relevant research on a larger scale.For example,few such researches have been done on an industrial scale.Herein,we review the very recent endeavors to bridge the gaps between fundamental research and industrial applications for water electrolysis.We begin by introducing the fundamentals of electrochemical water splitting and then present comparisons of testing protocol,figure of merit,catalyst of interest,and manufacturing cost for laboratory and industry-based water-electrolysis research.Special attention is paid to tracking the surface reconstruction process and identifying real catalytic species under different testing conditions,which highlight the significant distinctions of corresponding electrochemical reconstruction mechanisms.Advances in catalyst designs for industry-relevant water electrolysis are also summarized,which reveal the progress of moving the practical applications forward and accelerating synergies between material science and engineering.Perspectives and challenges of electrocatalyst design strategies are proposed finally to further bridge the gaps between lab-scale research and large-scale electrocatalysis applications.

Study on Filtration Performance of Silica/ Alumina Slurry in the Process of Recycling Mother Liquor of NaY Zeolite

In order to recover the SiO_2 contained in the mother liquor in the course ofNaY zeolite synthesis to minimize pollution, the influence of various preparation conditions on thefiltering velocity of gel slurry was studied using the SiO_2/Al_2O_3 gel recovered from the NaYmother liquor in the laboratory. The results of study had shown that at a SiO_2/Al_2O_3 ratio in thefeed equating to 9∶1 the SiO_2 recovery rate and Al_2O_3 utilization rate were high with a fasterflow velocity of the filtrate. The pH value of the system had great impact on the flow velocity offiltrate. Between the two methods for regulating the pH value, the one for formation ofsilica/alumina gel slurry by addition of sulfuric acid prior to adding aluminium sulfate in thesolution could secure a faster filtration velocity. The filtration velocity was decreased in tandemwith increasing SiO_2 concentration in mother liquor, meanwhile an increase in dry filter cakeyield.