Micromorphology and physicochemical properties of hydrophobic blasting dust in iron mines

The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.

Co-influencing mechanisms of physicochemical properties of blasting dust in iron mines on its wettability

This study explores the key physicochemical factors affecting the hydrophilic characteristics of iron mine blasting dust(BD). The BD is separated into an unwetted part(UWBD, hydrophobic part) and a wetted part(WBD, hydrophilic part). Its particle size, true density(TD), pore parameters, mineral composition, and surface compounds are comprehensively characterized and compared. The results indicate that a smaller particle size and more developed pore parameters are two key factors responsible for the strong hydrophobicity of the BD. The mineral composition of the BD has no direct effect on its wetting properties;however, it indirectly influences the deposition characteristics of the BD in water by affecting its TD. Unlike coal dust, the surface organic composition of the BD does not affect its wettability and the peak area of C–C/C–H hydrophobic groups in the C 1s X-ray photoelectron spectrum of the UWBD(45.03%) is smaller than that in the C 1s spectrum of the WBD(68.30%). Thus, eleven co-influencing processes of physicochemical properties of the BD on its wettability are summarized. This research sheds light on the key factors affecting the wettability of the BD.

Physicochemical factors affecting the wettability of copper mine blasting dust

To investigate the factors affecting the wettability of copper mine blasting dust,the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust(HLBD)and hydrophobic blasting dust(HBBD)using water flotation method.The physicochemical properties of HLBD and HBBD were measured and compared with each other.The properties included particle size distributions(PSDs),micromorphologies,pore structures,mineral components and surface organic carbon functional groups.The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability.Specifically,particle size of HBBD is smaller than that of HLBD,and their respiratory dust(less than 10μm)accounts for 61.74 vol%and 53.00 vol%,respectively.The pore structure of HBBD is more developed,and the total pore volume of HBBD is 1.66 times larger than that of HLBD.The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction(XRD);however,the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD,this may be the reason for the poor wettability of HBBD.This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

Development of Emission Factors for Quantification of Blasting Dust at Surface

Environmental impact assessment (EIA) and environmental management plan (EMP) is a statutory requirement for execution of new mining projects or for expansion of the operating projects. For this purpose, quantification of blasting dust emission is required. This can be done by developing emission factors for blasting. The concept is similar to that of specific charge in blasting. For mining operations other than blasting, quantification of dust can be done using emis- sion factors. Emission estimation techniques are very limited for blasting. In this study, the emission factors were de- veloped by carrying out a detailed field study at one of the largest opencast coal mines of India in all four seasons. Da- ta on atmospheric and meteorological conditions were generated by installing sodar and automatic weather station at the mine site. Respirable dust samplers were installed for monitoring of the dust emitted during coal or overburden bench blasting. Emission factors for dust concentrations were developed in gram per cubic meter of rock excavated. The developed emission factors were used to estimate dust emissions for adjacent mines due to similarity in mining and meteorological conditions. Seasonal variations in moisture contents in benches, where dust was monitored, indicated the lowest emission factors in monsoon due to high moisture in the bench materials. Similar field studies were also conducted at another coalfield of India for two seasons. It was found that the emission factors are site-specific.

Effects and mechanisms of fluorite on the co-reduction of blast furnace dust and seaside titanomagnetite

The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of-43 μm accounting for 69.02 wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO_2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage(≤4 wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF_2 and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F-when used as reducing agents, leading to weaker effects of fluorite.

Development and characterization of formulation of dust-suppressant used for stope road in open-pit mines

The components of dust-suppressant were determined based on the analysis on characteristics and mechanisms of road dust raising in open-pit mines. The components were initially selected from moisture agent, coagulation agent and surfactant. The optimal formulation was determined based on orthogonal test and using the water loss rate as the evaluation index. The performances of moisture releasing and adsorption, wind resistance of optimal formulation in the natural environment were tested. The results show that the formula obtained in experiments provide a good performance of moisture absorption and water retention, and it also had a good dust preventing and controlling performance due to its high surface strength and consolidation under dry conditions. It has good application prospects considering the wide variety of sources for materials and the simple preparation process.

Dust Distribution Study at the Blast Furnace Top Based on k-Sε-u_(p)Model

The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service life of detection equipment.The harsh environment inside a BF makes it difficult to describe the dust disthibution.This paper adresses this problem by proposing a dust distribution k-Sε-u_(p)model based on interphase(gas-powder)coupling.The proposed model is coupled with a k-Sεmodel(which describes gas flow movement)and a u_(p)model(which depicts dust movement).First,the kinetic energy equation and turbulent dissipation rate equation in the k-Sεmodel are established based on the modeling theory and single Green-function two scale direct interaction approximation(SGF-TSDIA)theory.Second,a dust particle mnovement u_(p)model is built based on a force analysis of the dust and Newton's laws of motion.Finally,a coupling factor that descibes the interphase interaction is proposed,and the k-Sε-u_(p)model,with clear physical meaning.ligorous mathematical logic,and adequate generality,is dleveloped.Siumulation results and o-site verification show that the k-Sε-u_(p)model not only has high precision,but also reveals the aggregate distribution features of the dust,which are helpful in optimizing the installation position of the detection equipment and imnproving its accuracy and service life.

Effect of Na2CO3 and CaCO3 on Coreduction Roasting of Blast Furnace Dust and High-phosphorus Oolitic Hematite

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.

Analysis of the quick corrosion of blast furnaces’gas pipes after the installation of dry-type de-dusting equipment and discussion about measures

Compared with the traditional wet-type de-dusting technology ,the dry-type de-dusting technology is considered to be environmentally friendly and energy-saving. However, the pipes carrying the de-dusted blast fiLrnace gas （BFG） tends to be corrosive more quickly and seriously. In order to investigate the reasons for the quick corrosion, the gas pipes and auxiliary bellows installed in Baosteel＇ s newly built BFG dry-type de-dusting system are studied. The corrosive properties of the condensed water, such as the pH value, are measured and analyzed. Meanwhile, various factors that may influence the corrosion rate of the pipes are studied by experiment. On the basis of the investigation and research, the causes of corrosion and leakage on the pipes are discovered. It is the process of dry de-dusting that is responsible ,to a large extent, for the quick corrosion of the pipes. The equipment of spray tower is introduced and its effects are then discussed. This tower is designed to eliminate most of chloridion and neutralized the acid by spraying the alkaline water to the dedusted gas flow. The practical operation shows that the tower helps to lessen the corrosiveness of the dry de-dusted gas effectively. The last part of this study analyzes the possible impacts of the dry-type de-dusting process of the newly built blast furnace （BF） on the main BFG piping which has been in the state of being corroded for years by estimating its potential corrosion rate, and some suggestions on maintenance are given as well.

Modeling Tensile Strength of Concrete on Partial Replacement of Ce­ment and Sand with Quarry Dust Ground Granulated Blast Furnace and Slag Silica Fumes

Tensile strength of concrete were examined on its partial replacement of cement and sand using ground granulated blast furnace and quarry dust.The study examines its behaviour at different dimensions.This is to monitor the variation effect of these parameters on the growth rates of tensile to the optimum curing age.These include non linear conditions of tensile state,non-elastic and its brittle behaviour at all times as it express zero conditions in tension.This means that it has the ability to with stand pull force.It also reflects its weak ability to handle shear stress thus tends to cause deformation in material as it has poor elasticity.The reflection of its brittle influence the rate of tensile behaviour from concrete ductility.These are known to be a material on modern mechanics of concrete.These are also considered as quasi brittle material.This behaviour was reflected as the system considered evaluating the growth rate of tensile strength that replaced cement and sand with these locally sourced addictives.The developed model monitor other reflected influential parameters such as variation of concrete porosity due it compaction in placements,tensile behaviour reflects these effect that subject it to mechanical properties of concrete.The study expressed the reaction of these parameters in the simulation,the evaluation of these affected the details variation of tensile growth rate at different water cement ratios and curing age.The tensile behaviour that was monitored are based on these factors in the study.The derived model were validated with the a researcher results[24],and both parameters developed best fits correlation.The study is imperative because the system expressed the behaviour of tensile strength from concrete at different dimensions.Experts can applied these concept to monitor tensile behaviour considering these parameters in its growth rates.

包钢高炉喷吹煤粉利用率的测定

利用透射光偏光显微镜,对包钢高炉重力除尘灰、旋风除尘灰和布袋除尘灰中的碳素种类进行定性和定量分析,以测定高炉喷吹煤粉利用率。测定结果表明,3号高炉喷吹煤粉利用率上下限分别为89.03%和79.46%,4号高炉的喷吹煤粉利用率上下限分别为91.51%和84.14%。认为,3号高炉和4号高炉所使用喷吹煤粉来自同一系列,因此可以通过采取稳定煤粉粒度波动、优化富氧鼓风和提高入炉焦炭强度等措施,来提高喷吹煤粉利用率。

露天矿山爆破抑尘技术研究与应用

针对司家营铁矿爆破粉尘大、扩散慢、滞留时间长的特点,通过分析粉尘产生原因,对水雾覆盖抑尘机理及影响因素进行研究,优化采场爆破方式方法,改善爆破抑尘效果,同时建立爆破抑尘管理体系,做到爆区抑尘全覆盖。

侧面爆破粉尘时空分布模拟分析

从开放性细颗粒物污染治理角度出发,建立建筑物拆除爆破产尘的几何计算模型,运用计算流体力学(CFD)工具,对给定环境风速下的建筑物周围压力场和速度场进行了模拟分析,并对侧面折叠爆破粉尘按R-R(Rosin-Rammler)分布,使用气流-粒子双向耦合的DPM模型研究了爆炸粉尘的时空分布。结果表明,下风侧因建筑物存在导致风速、压力急剧变化而产生涡流,涡流是影响爆破粉尘时空分布的关键因素之一。在时间上,爆破粉尘有气流拖曳运动状态和扩散态;在空间上,因重力作用致下部空间的粉尘浓度较大。

基于数值模拟的压入式通风隧道粉尘运移规律研究

为解决隧道钻爆作业施工期产生大量粉尘污染的问题,以四川卡拉水电站左岸交通隧道为研究对象,依据气固两相流理论,运用FLUENT软件构建了隧道粉尘扩散分布模型,对风流场分布特征和粉尘颗粒的运移规律进行模拟计算。结果表明:隧道风流场被划分为3个区域:涡流区、过渡区和稳定区,不同区域风流场特性有很大差异;风筒出口发射的高速气流运动过程中会逐渐扩大接触断面,并形成风幕;气流运动会导致隧道横截面方向粉尘质量浓度左低右高,但最后浓度分布将趋于平均;随着风速的增加,降尘速率增大,但有可能导致二次扬尘。最后,综合实际工程条件和施工要求,选择风速为24 m/s为最优排尘风速。研究成果可为隧道等地下工程通风系统改进和抑尘效果优化提供参考。

水雾包裹式隧道降尘技术试验研究

为了更快速有效地消除隧道爆破所产生的粉尘,该文提出“风筒水雾包裹式”与“车载水雾包裹式”两种喷雾降尘方案,并依托云南轿顶隧道进行现场试验。研究表明:对于“风筒水雾包裹式”除尘技术方案,掌子面处1号特征位置在降尘10 min后,粉尘浓度下降至3.87 mg/m^(3),满足规范要求;针对“车载水雾包裹式”的降尘技术,相比于无降尘初始状态,前20 min粉尘浓度下降最快,1、2、3号特征位置处粉尘浓度20 min后的降幅分别为70.6%、61.1%及89.9%。风筒、车载水雾包裹式技术均可达到相应的降尘效果,后者降尘效果更为明显。

钻爆施工隧道喷雾降尘数值模拟分析

为研究喷雾系统对隧道开挖后粉尘浓度的影响规律,采用Fluent软件建立长度为50m的隧道通风数值仿真模型,研究压入式风管风速、喷射角度、喷嘴数量和喷嘴至掌子面距离对喷雾除尘效率的影响。研究表明:随着风管风速的增加,粉尘颗粒加速运动,并且粉尘浓度最大位置逐渐远离掌子面。增加喷嘴数量可增大喷雾与粉尘的接触面积,提高粉尘颗粒与水雾作用的概率;在设置5个喷嘴且喷射角度为90°的条件下有利于降低粉尘浓度。喷嘴距离掌子面10m时可有效限制掌子面释放的粉尘,提高除尘效率。

三元共聚生物质基矿山爆破抑尘剂的制备及性能研究

以接枝共聚制备羧甲基纤维素钠(CMC-Na)-羧甲基淀粉钠(CMS-Na)-丙烯酰胺(AM)三元复合高分子抑尘剂,以黏度为测试指标,通过正交试验探索抑尘剂最优配比。用扫描电镜(SEM)、傅里叶红外光谱(FT-IR)、热重(TG)对接枝共聚产物进行表征,对抑尘剂黏度、抗风蚀性、保水性、渗透性等理化特性进行测试。结果表明:CMC-Na∶CMS-Na∶PVA∶AM=8∶8∶3∶16时,制备抑尘剂最大黏为52689 mPa·s;借助黏度及保水性指标确定抑尘剂喷洒最佳体积分数为8%;木质素磺酸钠和三乙醇胺最优添加量分别为抑尘剂质量分数的0.4%和4%。红外光谱显示丙烯酰胺接枝到羧甲基淀粉和羧甲基纤维素钠上,扫描电镜显示抑尘剂对粉尘的凝并和黏结性能显著,抗风蚀性实验表明抑尘剂固尘率为85.47%。

露天矿山环保抑尘剂研制及性能研究

针对石灰石露天矿爆破粉尘的防治问题,选取氯化钙、甲基纤维素、脂肪醇聚氧乙烯醚、丙三醇4种单体,采用正交实验法对4种单体进行四因素三水平实验。以pH值、黏度、渗透速率、保水率作为考核指标,采用极差法对实验结果进行分析得到最佳配方的复合抑尘剂(A),将抑尘剂(A)与水稻秸秆粉末纤维素酶解离液进行1∶1复配得到环保抑尘剂(B)。将两类抑尘剂与水进行实验对比,进行润湿性、抗破坏性、抗冻性、抗蒸发性表征,SEM测试和室内抑尘模拟实验。研究结果表明:抑尘剂(B)在抗冻、抗蒸发性及润湿作用上与抑尘剂(A)相似且都明显优于水;抑尘剂(B)固化性能更佳,微观形貌显示具有良好的黏结作用。在室内模拟风机风速为12.8 m/s,时间为20 min的扬尘模拟实验中,水、抑尘剂(A)、抑尘剂(B)的抑尘效率分别为32.22%、71.73%和73.25%。

隧道炮孔高精度定位及水封抑尘控制爆破施工工艺研究

文章以深圳外环高速公路东莞段工程第一施工合同段龙眼山隧道为工程背景,展开技术研究,总结、提炼了一套隧道炮孔高精度定位及水封抑尘控制爆破施工技术。在前期钻孔阶段,基于红外投影技术,采用红外投影设备将压缩成胶片的炮孔布设图直接投影至隧道掌子面上,再由工人进行油漆打点,钻孔工人根据油漆点位置进行精准钻孔施工。在隧道爆破阶段,将常规水压爆破施工技术进行改进,在传统封堵水袋中加入水溶性黏尘剂,显著增加了爆破后水雾的黏尘效果。在炮筒封堵中综合运用树脂类快凝封堵剂,显著减少了爆破能量的损失,同时强化其爆破效果,降低材料损耗。