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By Xinghua He, Shujing Zhu

"In this paper, the chemical composition, the content and the leachability of heavy metals in dredged sludge are tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the dredged sludge is considered as hazardous waste and must be solidified. The effect of solidifying the dredged sludge by the hydraulic ash-slag cementitious composites is studied, and it indicates that the heavy metals can be well immobilized if the mass fraction of the dredged sludge is appropriate. The heavy metals are immobilized within the hydraulic ash-slag cementitious composites hydration products through either physical fixation, substitution, deposition or adsorption mechanisms.IntroductionDredged sludge is classified as a hazardous waste because it usually contains concentrated heavy metals and chlorinated organic compounds, as well as soluble salts, and is also composed of very fine particles. Moreover, inorganic pollutants are typically associated with soluble compounds, which are, therefore, highly leachable from dredged sludge when dredged sludge is contacted by a liquid medium[l1. Thus, dredged sludge must be stabilized in order to reduce its environmental impact on the final disposal site. The frequent means of dredged sludge disposal used include(!) Chemical stabilization (2) acidic extractionChemical stabilization is translating mobile heavy metals into low dissolution and low toxicity form through chemical reaction. The commonly chemical medicaments are sodium hydroxide, soldium sulfide, thiourea, EDTA. But Zhao et al [ZJ found sodium hydroxide is not fit for Pb stabilization, the other three are effective, but the chemical properties of sodium sulfide are not stable, thiourea and EDTA are very expensive, and so it is very difficult to apply them. Moreover, because of the complexity of heavy metal conformation and dredged sludge composition, it is very difficult to find a cheap and prevalent stabilization medicament in point[31 ."

Jan 1, 2013

By X. Chen, F. An, H. Chen, Z. Wang

The bottom drainage roadway plays a crucial role in preventing coal and gas outbursts by using underground gas drainage methods. Therefore, it is essential to select the ideal position of the bottom drainage roadway. In this paper use a combination of geological data and numerical simulation to study the ideal position of the bottom drainage roadway, we taking the gas drainage of the first workface of No. 3 coal seam in the Yuxi coal mine in China as an example. The geological study showed a limestone marker layer at an average vertical distance of 14 m from the first mining face. Using this marker layer, the bottom drainage roadway could be excavated without the risk of accidentally exposing the coal seam, and less crosscutting borehole drilling from the bottom drainage roadway would be required. Based on the needs of gas control, the layout of the bottom drainage roadway was selected as an external stagger type. Combined with the numerical simulation results, when located 20 m outside of the mining workface ‘footprint’ on the horizontal projection, the bottom drainage roadway was a sufficient distance from the stress concentration area during mining of workface 1301, which facilitated roadway maintenance. Furthermore, the length of the crosscutting boreholes is also relatively short, which reduces the amount and cost of drilling. The results of this study are expected to provide a reference for the selection of an ideal position of the bottom drainage roadway in field engineering.

May 2, 2022

By Y. Sasseville

"Niobec has been using vibrating screens and screw classifiers as a double stage classification in its grinding circuit since the very beginning of its operation in St-Honoré. Most of the other mineral processing plants around the world uses cyclones as the classification device in their grinding circuit. The difference between these two methods are well known in terms of capital cost and grinding efficiency but the differences in terms of the impact on the downstream processing stages are a lot harder to predict and are case specific. In the interest of lowering the capital cost of a future expansion project, Niobec decided to test the cyclones in its actual grinding circuit and evaluate their impact on the recovery of the downstream processing stages as well as the operating cost of the mill. We switched between cyclones and screens for 8 month in 2013 and early 2014 and we are now operating only with cyclones since march 2014.INTRODUCTIONThe Niobec mine and concentrator were built in the mid 70’s and at that time, the mill was processing 1 500 tons per day. Over the years, many expansion projects have brought the plant to 7 000 tons per day. Throughout the initial concentrator design and commissioning, screens have been chosen over cyclones because of their higher classification efficiency which is known to reduce variability and limit the fine generation especially due to a high undersize classification efficiency. Just like many other plants, fine particle generation is a major problem at Niobec because of its negative effect on downstream processing stages. In the interest of lowering the capital cost of a future expansion project, Niobec’s engineering team decided, 35 years later, to test the cyclones in its actual grinding circuit and evaluate their actual impact on the final recovery and the operating cost of the mill.The grinding circuit is separated in two lines which will be called Circuit #1 and Circuit #2 along this paper. Circuit #1 is, as you can see in Figure 1, composed of a rod mill and two parallel ball mills in closed circuit with screens and screw classifiers. The screens oversize are sent to the screw classifiers while the undersize are sent to the next processing stage. The screw classifiers overflow are both sent back to the pump box while their oversize streams return in their corresponding ball mills for further grinding. Circuit #2 is, as you can see in Figure 1, quite the same as Circuit #1 except it has only one set of screw classifier and ball mill. Figure 1 also shows the modification in arrangement each circuits went through to integrate the new cyclones. One of the ball mills in Circuit #1 now appears dotted because it can still be used but is not now"

Jan 1, 2015

By Fuqiang Zheng, Shuai Wang, Ting Duan, Yufeng Guo, Tao Jiang, Andrew Yakovlevich Travyanov

Organic compound binder can effectively enhance the strength of green pellet and reduce the addition amount of binder during pelletizing. However, compared with traditional bentonite binder pellet, the compressive strength of the preheated and roasted pellets significantly declined. It is of significance to resolve this problem for the application of organic compound binder. In this paper, magnetite concentrate was used as raw material, carboxymethyl cellulose (CMC)- bentonite compound was used as binder, characteristics of preheated and roasted pellets and the effects of additives on that were systematically studied, The results show that sodium acetate can effectively improve the characteristics of the finished compound binder pellets. The compressive strength of the preheated and roasted pellets were increased by 52/N·p-1 and 342/N·p-1 respectively when the addition amount of sodium acetate is 2.2%wt of compound binder. Moreover, sodium acetate has no adverse effect on pelletizing process and drying characteristics of green balls.

Jan 1, 2015

By Minjun Tang, Jianfeng Zhou, Feng Chen, Linjiang Qing, Xiaolei Song, Yufeng Guo, Tao Jiang

"Reduction swellability index (Rsn and low temperature reduction disintegration index (RDI) of vanadium-titanium magnetite oxidized pellets are harmful to the processing of ironmaking, for example, causing serious gas permeability, decreased yield, higher coke ratio and more furnace dust. Thus, the improvements of RSI and RDI of vanadium-titanium magnetite oxidized pellets were investigated in this paper, including the pretreatment of raw material, additives of dolomite or boric acid, pellets treated in chloride solution and so on. The results showed that damp milling as pretreatment and boric acid added in pelletizing were conducive to the RSI which decreased 5% and 7% respectively, while they were not efficient enough in improving RDI. Dolomite was efficient in improving RSI, but had negative effect on RDI. There was no evidence to show that RSI and RDI would be improved when pellets were treated in chloride solution. Pursuing this further, the mechanism of those improvements were investigated.IntroductionIn the world, vanadium-titanium magnetite utilization is investigated around how to recover iron, titanium, vanadium, and divided into blast-furnace method and non-blast-furnace method according to respective characteristics. Blast furnace method [1, 2] can recover iron and vanadium effectively, but Ti02 cannot be recycled. Non-blast-furnace methods include rotary kiln-electric furnace method, pre-reduction electric furnace method, reduction- grinding method and sodium vanadium-rotary kiln-electric furnace method and so on. [3-7]Comparing to the Non-blast-furnace method, the method of blast furnace smelting has been put into industrial applications. And it has the following advantages: First of all, effective recycling iron and vanadium; Second, technical problems of high titanium slag in blast furnace smelting; Third, it has mature technology in blast furnace smelting."

Jan 1, 2013

By Wenshan Zhang

The industrial production experiments on Zn, Mn simultaneous leaching, impurity removal and ZnMnO2 simultaneous electrolysis were carried out. The process flow, technical requirement and research results about the experiments were discussed and the good technical quail-fixation and high quality of products were obtained. Reactions for each major technological process have been expatiated based on the thermodynamic analysis.

Jan 1, 2006

By Yuting Xue, Mark Van Dyke, Zoheir Khademian

Borehole scoping has been widely used in the U.S. underground coal mines as a method for geologic mapping and stability analysis because it is very useful for identifying rock types, voids, fractures, and formation boundaries through the direct observation of the borehole wall. An image stitching technique was proposed to generate panoramic borehole images from side-view borescopes in a previous study. However, the generation of panoramic borehole images can be affected by the borehole condition because the image stitching process highly depends on the key point detection and matching. The presence of dust and water could have a significant influence on the detection of key points. In this study, the influence of borehole conditions on panoramic borehole images was studied from the success of image stitching and the visibility of geologic features and lithology changes. Borehole videos recorded at different times, when the same borehole was freshly drilled, freshly washed with water and 12 days after washing, were processed with the proposed technique. The comparison of the stitched images shows that the presence of dust has minimal influence on the image stitching process but shows significant negative effects on the visualization of geologic feature and lithology change. In addition, the presence of water can significantly hinder the image stitching process, which in turn helps in identifying lithology change. Borehole scoping aids in identifying and mitigating hazardous conditions in underground mines, and this study provides preliminary inputs into identifying optimum borehole conditions for geologic mapping with panoramic borehole images.

Feb 1, 2025

By Feng-guang Li, Rui Guo, Ju Zhang

Cooling stave is one of the most important equipment of blast furnace for iron making. The heat transfer performance and service life of the cooling stave, to a large extent, determines the efficiency and economy of the iron making process. In this paper, a 3-D heat transfer model of cooling stave was founded by ANSYS based on FEM theory, and the heat transfer characteristics of cooling staves which were made of different materials (cast iron, cast steel and copper) were analyzed. Then, several suggestions on choosing material of cooling staves were given according to the calculation results and the actual working conditions of the cooling staves.

Mar 1, 2017

By Honglei Zhang, Yue Wang, Guotao Xu, Li Liu

The influence of rich oxygen atmosphere on the properties and structure of castables used in the hot wind pipe of blast furnaces was analyzed. Results show that the cold compressive strength of castables is affected by the change of rich oxygen volume in the wind pipe, the bulk density decreases and apparent porosity of castables increases with the addition of rich oxygen in wind pipe. With the addition of rich oxygen, the velocity of heat transfer increase and result of the steel shell become over hot out of safe limit at the thin lining in hot wind pipe.

Jan 1, 2015

By Dengfu Chen, Yunwei Huang, Mujun Long, Kui Lv, Pei Xu, Lin Bai

The surface temperature of continuous casting slab in the secondary cooling zone is a key parameter of production control. However, the accuracy of radiation temperature measurement of high temperature casting slab is greatly affected by the environmental factors, such as water vapor, spray, water film and other participational medias during continuous casting process. In this paper, the radiation characteristics of water vapor and its influences to radiation temperature measurement of continuous casting slab were investigated. Based on the database HITRAN 2004 and the measuring principle of monochrome thermometer & colorimetric thermometer, the measuring errors under different operating infrared spectral wavelength were compared. Results showed that spectral region with wavelength nearby 1.0μm or 1.6μm would be the optimum for high temperature infrared thermometer used under the conditions with moist steam, water spray and water film at the secondary cooling zone in steel continuous casting.

Jan 1, 2016

By Y. H. Hu, X. X. Zhang, Z. F. Dai, H. J. Huang, Q. S. Huang

"In order to get a more comprehensive understanding of the interaction of fine fluorite particles and bubbles, the electro-flotation was conducted, a high speed CCD was used to determine the bubble size distribution, and the results were analyzed using the models of collision and attachment. The electro-flotation was performed in a modified Hallimond tube. The results show that for different fluorite with size of 0 -10µm, 10 -38µm, 38-74um, there is a matching range between the different particle sizes and cathode aperture size (38um, 38um, 74um) to reach highest recovery. In addition, improving the concentration of collector is benefit for the flotation recovery due to the ability of collector to decrease the bubble size and prevent the merger of bubbles. Furthermore, theoretical calculation of collision, adhesion probability and collection probability is in agreement with the experimental data for electro-flotation recovery of fluorite.INTRODUCTIONFluorite is widely distributed, and has been found in more than 40 countries around the world. As fluorite minerals are easy to float, flotation is used as the best method of the current recovery of fluorite (Yang and Ai, 2016; Chen et al., 2017). In the field of mineral processing, the flotation of fine particles is particularly difficult, caused by the small quality and large surface (Sun et al., 2006). Flotation is now considered to contain three subprocesses, including the collision, attachment and detachment between the particles and bubbles (Sun et al., 2011). The collision of particles with bubbles is related to factors such as particle size and density, bubble size, bubble rise rate (Qin et al., 2012). Zongfu Dai et al. (2000) summarized the particle-bubble collisions models in detail and compared the experiment results with the model predictions. However, particle-bubble interactions occur in complex and turbulent flotation environments (Xing et al., 2017). Both thermodynamics and dynamic factors affect the adhesion of particles on bubbles surface (Schulze, 1989; Shahbazi et al., 2010). Scheludko et al. (1976) believes that the necessary condition for successful adhesion of particles on bubbles is that the contact time is greater than the induction time. The probability of adhesion between particles and bubbles increases with the increase of bubble size, but if the particle size is too small, the probability of adhesion decreases instead (Ren, et al. 2014; Norori- McCormac et al., 2017). After the particles adhere to the bubble surface, the particles will slide down to the bottom of the bubble due to gravity. At this point, the gravity, inertial centrifugal force and fluid force promote the desorption of particles from the bubble surface, while the surface tension, surface hydrophobic force maintain the stability of particles-bubble combination (Ralston et al.,2017). In addition, in the process of rising to the foam layer, desorption can also occurs. The purpose of this study is to observe the flotation behavior of fine fluorite with different size and to get a more comprehensive understanding of the interaction of fine fluorite particles and bubbles."

Jan 1, 2018

Study on the Interaction Mechanism of Flotation Reagents and Rare-Earths-Bearing Phosphate Ore

Sep 13, 2010

By Q. F. Wang, M. H. Lai, T. Q. Liu, G. G. Dong

Compared with the traditional pre-treatment process, biological oxidation process has many advantages including higher gold recovery, less cost, easier operation. The bio-oxidation reactor is the most important equipment for biological oxidation process. In this paper, the characteristics of biological oxidation are investigated, and the design principles are proposed based on laboratory tests. Both increasing the tank height and taking new inflation system can enhance higher dissolved oxygen. The new type of large-scale industrial bio-oxidation reactor is designed, which is 9.5 m in diameter and 10 m in height. The bio-oxidation reactor metallurgical performance has been tested by industrial-scale experiment. The slurry of flotation concentrate is divided into two parts to feed two bio-oxidation reactors. The feeding rates of two reactors are adjusted on the basis of getting the same content of S, Fe, As in overflow. The result shows that the feeding rate of the new type of 700 m3 bio-oxidation reactor is 3.72 m3 per hour, and the feed rate of the conventional 700 m3 bio-oxidation reactor was 3.23 m3 per hour. The processing capacity of the former is 15.2% higher than that of the later, which demonstrates the new type of bio-oxidation reactor has higher oxidation rate.

Jan 1, 2015

By Uchil Jayagopal, M. Krishna, P .. V. Krilpakara, S. Manjunath

"There have been a pioneering efforts over the last forty years in the development of metal matrix composites (MMCs) as a new engineering materials, having improved properties, light weight characteristics and competitive costs compared to traditional materials. Following recent advancements in casting technology and the use of melt stirring device by foundries, discontinuously reinforced MMCs where prominent alloys are reinforced with particulates or short fibres and the being employed ·in the production of castings targeted for automotive and aerospace application.The ZA-27 alloy has a high strength compared to zinc or alluminium alloys with a lower melting temperature. The main objective of the present research is to study the effect of quartz particles on the mechanical behaviour of ZA-27 alloy composites. The results showed that the ultimate tensile strength, hardness, Young's modulus of the composite gradually increased with increase in the weight percentage of the quartz reinforcement. However overall ductility decreased with an increase in quartz reinforcementIntroductionMetal matrix composite (MMCs) offer outstanding benefits as they combine metallic properties with ceramic properties there by yielding improved physical and mechanical properties.1Among the various type of MMCs particulate reinforced composite are the most versatile and economical2. By suitable choice of metal matrix and particulate system a wide range of properties combination can be obtained such as strength, modulus, fiiction.al resistance, tribological performance and machinability. These composites are capable of replacing conventional alloys in a considerable range of applications. They also offer significant saving in energy and resources"

Jan 1, 2000

By Zhu Yangge, Hu Xiaoxing, Feng Qiming, Zhang Guofan, Zhang Xingrong

"During the flotation process of ilmenite and titanaugite with fatty acid as collector, unavoidable ions such as Ca2+, Mg2+, Al3+, Fe3+ and Fe2+ demonstrate considerable influence on the floatability of the minerals. In this study, flotation test, zeta potential test, and solution chemistry calculation were adopted to investigate the mechanism of how these metal ions affect the floatability of ilmenite and titanaugite in different pH conditions. The results show that in weak acidic solution, Ca2+ and Mg2+ mainly freely exist in the solution with little adsorption on mineral surface, and their reaction ability with oleate ions is weaker than active site on ilmenite surface (Fe), thus they show negligible effect on the flotation of ilmenite; Al3+ shows similar reaction ability with oleate ion compared to Fe3+, which lead to competitive reaction with collector, so the flotation of ilmenite is depressed. While Fe3+ can adsorb on surface of titanaugite in the form of Fe(OH)3, and it shows stronger reaction ability with oleate ion compared with active site on titanaugite surface (Ca and Mg), which proves an activation effect on titanaugite flotation. In alkaline solution, all these five kinds of ions can adsorb on titanaugite surface, and the floatability of titanaugite will be activation. Based on the above analysis, it can be deduced that in the flotation system using fatty acid as collector, the adsorption of metal ions on mineral surfaces and the stronger reaction ability with collector than active site on mineral surfaces, are the two prerequisites for metal ions show activation effect on mineral flotation.INTRODUCTIONIn flotation pulp, the existence of metal ions is often inevitable. There are two sources for these metal ions: the first part is generated in grinding and flotation process due to the oxidation, reduction, corrosion or dissolution of minerals or grinding medium; the second part is from the flotation water or the addition because of the technology need. The metal ions in the pulp have a considerable influence on mineral flotation. Earlier researches are focus on the activation effect of mineral floatation by metal ions to obtain a higher flotation efficiency, many effective activators were found, such as Cu2+ activated sphalerite, Pb2+ activation wolframite, and Ca2+ activation quartz flotation, these metal ions have become the commonly used activators in industrial production. And many studies attempted to explain the mechanism of how metal ions affect the floatability of minerals. James (James et al, 1972) suggests that metal hydroxide precipitation is the main component leads to activation effect, while the study of Fuerstenau (Fuerstenau, 1976) showed that the metal ion hydroxyl complexes played significant role. In recent years, the reuse of mineral processing wastewater has attracted more attention (Rao et al, 1989; Liu et al, 2013; Wang et al, 2014), as a main component in flotation wastewater, the influence of “unavoidable ions” on flotation process still need in-depth study."

Jan 1, 2018

By C. H. Tsau

The intermetallic compounds of Ni-25Al-xFe, x is 20-40 at.%, were prepared by arc melting and drop casting into ingots, and were rapidly solidified into ribbons by melt spinning. The microstructure evolution of these alloys with varied Fe content were examined by the x-ray diffraction, optical microscope, scanning electron microscopy and transmission electron microscopy. The results reveal that two phases, {y'} and {B} phases, are existing in the alloys with low Fe content, and the microstructure changes from the mixture of y' and {B} phases to a single 0' phase when the Fe-content reaches to 40 at.%. Also, the formation of y' phase will be suppressed by rapidly solidified process. For annealing both of the melt-spun and the cast specimens, a disorder 0 phase was revealed in both of the ribbon and the cast ingot of Ni-Al-Fe alloys with higher Fe content. In addition, increasing the increment of iron which substituting nickel in this alloys results in increasing the lattice parameter of both {y'} and{B} phases.

Jan 1, 1992

Study on the Mineral Processing Technology of Low-Grade Refractory Lead-Zinc Oxide Ores Containing Argillaceous and Carbonated Gangue in Yunnan

Sep 13, 2010

By Zhang Hongzhen

The fast convergence of boundary is a major problem of probability integral method, especially for the prediction of mining under thick alluvium, abandoned mine goaf, etc. To solve this problem and improve the accuracy of probability integral method, a modified model is constructed for surface movement and deformation based on theoretical analysis. In which, three weighted values i.e. 1, -1/t1, 1/t2 are set for the mining movement and deformation of three different major influence radius i.e. r1, R1, R2, respectively, then the parameters are selected as following: (1) Parameters are inversed based on the observation data, in which the subsidence factor q, deviation of inflection point s, displacement factor b are considered as generic parameters, the tangent of major influence angle tanß is modified as tanß2, that is the major influence radius r is modified as r2. (2) Inversion parameters of tangent of major influenceangle tanß or major influence radius r, based on the observation station edge data which beyond major influenc eradius distance from work-face mining boundary. The inversed tanß and r will be used as tangent of major influence angle tanß1 and major influence radius r1, respectively. (3) Other relevant parameters i.e. t1, t2, R1, R2, are calculated with the algorithm of this paper. A comparison experiment between the traditional and modified models has been conducted using the observation data from a observation station, the results show that in its central area, 58.6 percent of observation points accuracy is improved and 36.6 percent is decreased, while in its edge area, 61.5 percent is improved and 15.4 percent is decreased, totally, 68.6 percent is improved and 30 percent is decreased. Therefore, we can draw the conclusion that our modified model can improve the prediction predication accuracy, in particular, the boundary region.

Jan 1, 2014

Study on the New Flow Sheet and Wastewater Recycling for Xiaoliuguo Copper-Bearing Low-Grade Scheelite Ore

Sep 13, 2010

By Z. Hu

A complex polymetallic sulfide ore in Yunnan, China, has various valuable minerals, which are Chalcopyrite, Galena, Pyrite, Gold, Silver, and Magnetite. A reasonable new flowsheet with a bulk flotation and a flotation separation of sulfide minerals that are Chalcopyrite, Galena, and Pyrite was carried out at first stage. After that tailings were treated by low intensity magnetic separation to achieve magnetite concentrate. A high Pb concentrate assaying 60.00 percent Pb at total recovery of 75.71 percent with 40.50 g/t Au and 1390.00 g/t Ag, a final high Cu concentrate assaying 24.45 percent Cu at high recovery of 92.03 percent and a magnetite concentrate assaying 60.78 percent Fe at recovery of 33.61 percent with 18.45g/t Au and 234.99 g/t Ag, are obtained. The total recovery of Gold and Silver in Pb concentrate and Cu concentrate reached 71.63 percent and 67.32 percent, respectively. It is shown, that this new flowsheet could realize efficient recovery for all of the valuable minerals in the ore and is easy to be industrialized. Keywords: bulk flotation, magnetic separation, polymetallic sulfide ore, depressant

Sep 1, 2012