The caving and sliding control of surrounding rocks on large coal roadways affected by abutment pressure

For the caving and sliding control of roadways with large cross-section, thick mudstone roof and abutment pressure influence, the cable truss system is proposed and its support mechanism is thoroughly analyzed in this paper. Furthermore, according to the geometric size and ground pressure conditions on field coal roadways Nos. 101, 102 and 103 in Xinyuan Coal Mine, three types of cable truss support systems are designed for obtaining the optimum cable truss support system. Then the corresponding parameters for each support design are determined by use of the numerical simulation method, and three kinds of support systems are put into practice. The field observation results show that roof should be effectively controlled by the normal cable truss structure consisting of two long cables and one connector, and both coal sides can be protected by the simplified cable truss structure composed of two short cables and one channel bar. Finally, the optimal support system is gotten which is much better than the other two support designs in rock deformation control effect and economic profits.     

微波消解-原子荧光光谱法测定垃圾焚烧飞灰中铅

采用微波消解-原子荧光光谱法测定了垃圾焚烧飞灰中铅的含量。重点研究了铁氰化钾的用量以及加入盐酸羟胺对测定结果的影响。试验结果表明:加入铁氰化钾可以促进铅烷生成,盐酸羟胺可起到抑制干扰的作用。方法的检出限为0.39μg/L,回收率为83.6%～101.3%。     

Pyrolysis characteristics of the mixture of printed circuit board scraps and coal powder

Thermogravimetric (TG) analysis and infrared spectroscopy were used to analyze the pyrolysis characteristics of printed circuit board scraps (PCBs), coal powder and their mixtures under nitrogen atmosphere. The experimental results show that there is a large difference between waste PCBs and coal powder in pyrolysis processing. The pyrolysis properties of the mixing samples are the result of interaction of the PCBs and coal powder, which is influenced by the content of mixture. The degree of pyrolysis and pyrolysis properties of the mixture are much better than that of the single component. The TG and the differential thermogravimetric (DTG) curves of the PCBs mixed with coal powder move towards the high-temperature zone with increasing amount of coal powder and subsequently the DTG peak also becomes wider. The Coats–Redfern integral method was used to determine the kinetic parameters of pyrolysis reaction mechanism with the different proportion of mixture. The gas of pyrolysis mainly composes of CO₂, CO, H₂O and some hydrocarbon. The bromide characteristic absorption peak has been detected obviously in the pyrolysis gas of PCBs. On the contrary, the absorption peak of the bromide is not obvious in pyrolysis gas of the PCBs samples adding 40% coal powder.     

Risk management and workers’ safety behavior control in coal mine

According to the risk management characteristics and the actual needs of safety production in coal mine, we thoroughly analyze the system of risk management method in coal mine and implement it in Geting Coal Mine. The system manages and controls the potential accident risks, hazard sources and human behavior risks. On this basis, the system of workers’ safety behavior control technology in coal mine is further studied, the “three disobeying” is classified and managed, the “three disobeying” database and safety countermeasures database are established, and the application software - the system of risk management and safety countermeasures optimization in coal mine based on B/S mode is developed and applied, which uses intranet to analyze and supervise the “three disobeying”, publish early-warning information, optimize management and control countermeasures; at the same time, the important prompting messages can be automatically sent to the mobile phones of relevant managers and the person in charge through public communication system in order to improve the real time capability and effectiveness of unsafe behavior control. The technological system and application software implemented in Geting Coal Mine has achieved good results.     

A CART technique to adjust production from longwall coal operations under ventilation constraints

Methane emissions in longwall coal mines can arise from a variety of geologic and production factors, where ventilation and degasification are primary control measures to prevent excessive methane levels. However, poor ventilation practices or inadequate ventilation may result in accumulation of dangerous methane-air mixtures. The need exists for a set of rules and a model to be used as guidelines to adjust coal production according to expected methane emissions and current ventilation conditions.In this paper, hierarchical classification and regression tree (CART) analyses are performed as nonparametric modeling efforts to predict methane emissions that can arise during extraction of a longwall panel. These emissions are predicted for a range of coal productivities while considering specific operational, panel design and geologic parameters such as gas content, proximate composition of coal, seam height, panel width, cut height, cut depth, and panel size. Analyses are conducted for longwall mines with and without degasification of the longwall panel. These models define a range of coal productivities that can be achieved without exceeding specified emissions rates under given operating and geological conditions.Finally, the technique was applied to longwall mines that operate with and without degasification system to demonstrate its use and predictive capability. The predicted results proved to be close to the actual measurements to estimate ventilation requirements. Thus, the CART-based model that is given in this paper can be used to predict methane emission rates and to adjust operation parameters under ventilation constrains in longwall mining.     

Study of coal oxidation behaviour in re-opened sealed heating

Possible changes in the oxidation behaviour of coal in the spontaneous combustion site of re-opened sealed heating were studied. Two samples of bituminous coal and three types of coal pre-treatment procedures were applied to simulate in situ conditions at the “spon-com” site: i) pre-oxidation of coal, ii) pre-heating of coal under inert gas, and iii) immersion of pre-heated coal in liquid water. Pre-treated samples were then examined for the production rate of the indication gases evolved during oxidation and for oxidation heat effects. Two main conclusions were drawn with respect to oxidation of the coal in re-opened sealed heating: i) carbon monoxide and unsaturated hydrocarbons maintain their relevance as spontaneous combustion indication gases, however, increased production of both carbon oxides can be expected; ii) coal in the extinguished spontaneous combustion site gains increased susceptibility to the self-heating process.     

Synthesis of mesoporous silica materials from municipal solid waste incinerator bottom ash

Incinerator bottom ash contains a large amount of silica and can hence be used as a silica source for the synthesis of mesoporous silica materials. In this study, the conditions for alkaline fusion to extract silica from incinerator bottom ash were investigated, and the resulting supernatant solution was used as the silica source for synthesizing mesoporous silica materials. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, XRD, FTIR, SEM, and solid-state NMR. The results indicated that the BET surface area and pore size distribution of the synthesized silica materials were 992 m²/g and 2–3.8 nm, respectively. The XRD patterns showed that the synthesized materials exhibited a hexagonal pore structure with a smaller order. The NMR spectra of the synthesized materials exhibited three peaks, corresponding to Q² [Si(OSi)₂(OH)₂], Q³ [Si(OSi)₃(OH)], and Q⁴ [Si(OSi)₄]. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric Si–O stretching. Thus, mesoporous silica was successfully synthesized from incinerator bottom ash. Finally, the effectiveness of the synthesized silica in removing heavy metals (Pb²⁺, Cu²⁺, Cd²⁺, and Cr²⁺) from aqueous solutions was also determined. The results showed that the silica materials synthesized from incinerator bottom ash have potential for use as an adsorbent for the removal of heavy metals from aqueous solutions.     

一种烟气脱硝预除尘装置

提出了一种新型的用于脱硝反应前的高效除尘装置；该装置包含与烟气进口相连接的烟气管道和与烟气管道输出口连接的脱硝反应器，在烟气管道靠近烟气进口位置设有两级预除尘器。一级预除尘器为设置在竖直烟道最底部的锥形灰斗，二级预除尘器包括设置在水平烟道扩径处的角形挡板和平形挡板。经预除尘装置后使烟气的烟尘含量大大减少，可显著提高脱硝效果。     

Life cycle assessment of sewage sludge co-incineration in a coal-based power station

A life cycle assessment was conducted to evaluate the environmental and economic effects of sewage sludge co-incineration in a coal-fired power plant. The general approach employed by a coal-fired power plant was also assessed as control. Sewage sludge co-incineration technology causes greater environmental burden than does coal-based energy production technology because of the additional electricity consumption and wastewater treatment required for the pretreatment of sewage sludge, direct emissions from sludge incineration, and incinerated ash disposal processes. However, sewage sludge co-incineration presents higher economic benefits because of electricity subsidies and the income generating potential of sludge. Environmental assessment results indicate that sewage sludge co-incineration is unsuitable for mitigating the increasing pressure brought on by sewage sludge pollution. Reducing the overall environmental effect of sludge co-incineration power stations necessitates increasing net coal consumption efficiency, incinerated ash reuse rate, dedust system efficiency, and sludge water content rate.     

污泥焚烧残渣水热合成NaPl型沸石和水钙沸石的性质研究

本文以污泥焚烧残渣为原料,以传统水热合成方法制得NaPl型沸石和水钙沸石,并对其相关指标进行表征．经x射线衍射、扫描电镜和红外光谱测定表明,制得的产物为无其它杂晶生成的NaPl型沸石和水钙沸石,且具有放射束片状晶体形貌和沸石骨架结构．与原污泥焚烧残渣相比,合成沸石的比表面积和阳离子交换容量提高了47倍、17倍,分别达到...