Search Documents

By Verya Nasria, William Bent, William Hogan

"The South Hartford Conveyance and Storage Tunnel (SHCST) project is a significant component of the Hartford Metropolitan District’s (MDC) long-term control plan (LTCP), which is overseen by the Connecticut Department of Energy and Environmental Protection (CTDEEP). This project will address a portion of the MDC’s Clean Water Project (CWP), which will reduce combined sewer overflows (CSOs), eliminate sanitary sewer overflows (SSOs), and reduce nitrogen released into the Connecticut River. The purpose of the SHCST project is to eliminate West Hartford and Newington SSOs, eliminate Franklin area CSOs discharging to Wethersfield Cove and minimize CSO discharges to the South Branch Park River. The locations of each overflow are shown in Fig. 1. In 2010, the district prepared a preliminary design report (PDR) for the SHCST project, which included relief of the Folly Brook trunk sewer and proposed to keep the tunnel boring machine (TBM) retrieval shaft within the city limits of Hartford. Figure 1 shows the 2010 PDR recommended tunnel route. Subsequent to the PDR, the objectives of the SHCST have slightly shifted. In accordance with ongoing revisions to the LTCP, relief of the Folly Brook Trunk Sewer is no longer necessary. Additionally, the MDC has decided to perform less sewer separation in the Franklin Avenue drainage area. To replace the sewer separation, new relief points are proposed within the Franklin area and will be diverted to the SHCST. Figure 1 also shows the current recommended tunnel route (Alignment F). During 2012, the MDC conducted an evaluation of the potential of connecting the proposed North Tunnel (originally proposed as an independent tunnel with its own pump station) into the South Hartford Conveyance and Storage Tunnel. This evaluation concluded that the two proposed tunnels could reasonably be connected together and operated as a single tunnel system utilizing the tunnel pump station at the eastern terminus of the South Hartford Tunnel (Fig. 2). It also was concluded that this alternative was less costly than two independent tunnel systems."

Jan 1, 2014

By Peter Metcalfe

"Wireless communication in the mineral processing environment is not as simple as it is in the home or office environment. The correct design of a wireless network in the mineral processing environment can offer a more flexible and lower cost installation than the transitional fiber networks. However with the flexibility of a wireless solution, also comes some limitations. By reviewing the plant requirements along with weighting the wireless benefits and limitations it is possible to design a network that combines the robustness of a wired solution with the mobility of a wireless solution. This paper addresses some wireless design considerations and it looks at some real life examples in the following areas: •,Meshed wireless network for high levels of redundancy •,Wireless instruments (such as HART, Modbus and others) •,Portable devices for mobile operators •,Network monitoring for plant personnel (it’s no longer just for IT people) INTRODUCTION Typical networks used in the mineral processing environment consist of a fiber network infrastructure with industrial switches used to connect the network devices. These fiber networks can be redundant or put into a ring topologies to offer a higher level of availability. Fiber networks have the benefits of: •,Immunity to noise from power and grounding issues •,Ability to span long distances (2km for multimode fiber and 20km for single mode fiber) •,Maintainable “off-the-shelf” technology Fiber networks however have some drawbacks, such as: •,Relativity high initial installation cost for cable trays, poles, trenches and pulling and termination of cable. •,Fixed geographic topology, adding future fiber drops may be challenging and expensive. •,Mobile users are not considered. Integrating a wireless network with a fiber network can offer the best of two worlds, a reliable high speed backbone for mission critical activities and a wireless network for remote applications and mobile users."

Jan 1, 2014

By P. Braga, A. Chaves, S. França, A. Luz

"In Brazil, there are no official reserves of molybdenum, and the unofficial reserves are modest. Therefore, the molybdenum ore (molybdenite) produced as a co-product or by-product of emerald mining in the region of Campo Formoso, BA, has arisen as the only economic option. The flotation process is commonly used in Brazil for the recovery of molybdenite from emerald mining tailings, but it produces low-content molybdenite concentrates, thereby resulting in a product with low economic value. The molybdenite concentrate produced in Campo Formoso contains 83.5% MoS2 (50% Mo), which is less than the international standard product that contains > 90% MoS2 (54% Mo).This low value is due to the presence of talc, which is a naturally hydrophobic mineral that is also floated with the molybdenite during the flotation process. Separability studies were done in a Partridge-Smith cell using dextrin and quebracho as a molybdenite depressor in solution at different concentrations and pH values to produce a technical-grade concentrate (i.e., 90% MoS2). These basic studies were accompanied by measurements of the zeta potential and contact angle, which was determined by the capillary rise method. The results of these floatability studies were used in bench flotation tests, which were performed in a Denver laboratory flotation cell. A molybdenite concentrate of 93.4% MoS2 was obtained when dextrin was used at a concentration of 100 g/t."

Jan 1, 2014

By S. Botes, H. van der Merwe

While the refractory lining contains the process on a steady-state basis, the tap-hole must provide a channel for transport of molten materials at discreet intervals, with thermal cycling as routine. The tap-hole introduces a discontinuity in any lining, and this fact can lead to failure in the region around the tap-hole before general lining failure occurs. Hence there is a need for a rapid and reliable tap-hole repair technique that can be readily implemented in conjunction with all types of linings. The UCAR®V Repair supplied by GrafTech is a durable solution capable of repairing all types of lining designs and has been extensively utilized in the ferroalloy industry. More than 20 UCAR®V Repairs have been successfully performed in South Africa alone. This paper describes the system in general and reviews recent repairs and their unique challenges.

Jan 1, 2014

By J. Finch, F. Rosenblum, McGill University

The self-heating of sulphides can be a major hazard in mining operations and concentrate handling, particularly during transportation and associated storage. Self-heating results from the oxidation of sulphide minerals and can vary from being insignificant to potentially hazardous to life and infrastructure. It is essential that there be a reliable test methodology that can categorize a given sulphide material as to its self-heating potential. By their nature, sulphide ores and concentrates are complex and variable mineral combinations making it difficult to predict their self-heating behavior a-priori based on mineralogy or with a simple "snapshot" test. Furthermore, self-heating behavior will depend on the state of oxidation of the sulphides as well as time, temperature and humidity. A review of available testing apparatuses and protocols that can be used to assess self-heating potential is presented. Each of these methodologies was examined in relation to its ability to predict the latent self-heating hazard of a sulphide material. Several of the methods were compared to illustrate their strengths and weakness. The results indicated that a number of the test protocols may produce false negative indications of self-heating potential, constituting an obvious concern to the industry.

Jan 1, 2014

By P. Zarate, M. Peart, T. Bhambhani, D. R. Nagaraj

More than 50% of all the molybdenum produced in the world is a by-product of copper production. A bulk Cu-Mo concentrate is first produced, which is subsequently separated into Cu and Mo concentrates. The Cu-Mo separation circuits rely on the use of inorganic Cu sulfide depressants such as NaSH, Na2S, and Nokes, which are hazardous, and sometimes require very large dosages for effective depression. Synthetic polymeric depressants are safer and more efficient, and are now being used on the plant-scale. Data presented in this paper demonstrates that these polymeric depressants can replace 50-90% of all the NaSH in Cu-Mo separation at a fraction of the NaSH dosage. In this paper we provide an overview of the mechanistic and practical aspects of the Cu-Mo separation with inorganic depressants and polymeric depressants. Important practical aspects include depression dynamics (related to conditioning time and rate of depression), optimum pH for effective separation, the role of pH modifiers such as lime and NaOH, and the effect of flotation gas on the efficacy of the separation. Using nitrogen as flotation gas, the NaSH consumption can be reduced by up to 95% by using a small amount of polymeric depressant. The experiments with conditioning time demonstrate that there is a significant rate component to the depression mechanism with NaSH, which is absent for the polymeric depressant system. This has important implications in the effective use and application of the depressant. It is also demonstrated that the pH modifier type (NaOH or Ca(OH)2) has no significant effect on separation efficiency and Mo recovery (i.e. Ca2+ ions do not depress MoS2 in the Cu-Mo separation).

Jan 1, 2014

Quantitative seismology is an important tool for investigating mineinduced seismicity and the quantification of the seismic rock mass response. The spatio-temporal interpretation of seismic data within an ever-changing three-dimensional mining environment provides some challenges to the interpretation of the rock mass response. A grid-based approach for the interpretation of spatial variation of the rock mass response provides some benefits compared with approaches based on spatial filters. This paper discusses a grid-based interpretation of seismic data. The basic methods employed in the evaluation of the parameter values through space are discussed and examples of applications to different mine sites given.

Jan 1, 2014

By Jae-Chun Lee, Sadia Ilyas

We investigate the technical feasibility of bioleaching of metals from low grade sulphidic ore. Experiments were conducted with an adapted consortium of Sulfobacillus thermosulfidooxidans and Thermoplasm acidophilum in batch bioreactors (1.5 L), small columns (10 kg ore load, 8 % S0 sludge) and large columns (80 kg ore load, 12 % S0 sludge). Approximately 83 % Ni, 85 % Cu, 55 % Fe and 81 % Zn was leached out in batch mode while 93 % Ni, 89 % Zn, 81 % Cu and 65 % Fe was leached out in column reactors. Bioleaching potential improved by acid pre-leaching, adaptation of microbial consortium and periodic bleeding of effluents.

Jan 1, 2014

By Reinol Compañero, Ivy Gonzales, Herman Mendoza, Brian Buenaventura

"The extraction of gold in the Philippines has been a significant challenge for the past decades. Around 70-75% of gold mined in the country can be accounted from the small-scale mining industry which primarily use the traditional cyanidation and amalgamation; processes which have been advocated due to its adverse affects to health and environment. To address this challenge, an alternative clean and sustainable technology was developed for the small-scale miners to recover gold and other metal/mineral values efficiently from Philippine ores. An initial survey was conducted and followed through with extensive mineralogical investigations ascertain the best method applicable. It was determined that Philippine gold occur in ore as (1) very fine particles in the microns range, (2) free-milling, which is in abundance, and (3) locked particles with sulfides --- it was concluded that enhanced gravity concentration and flotation are viable alternatives. A comprehensive test regime was followed to check the response of the ores obtained from different small-scale mining districts across the country. It was shown conclusively that the gold ores respond positively, with recoveries using gravity concentration and flotation of at least 95% and 88%, respectively; exceeding the nominal recoveries using cyanidation or amalgamation. A specific process flow was designed for each type of ore with customized parameters. It was determined that while capital expenditure of implementing these alternative processes is higher than what is currently being used, the operational aspects show that it is much more economical to apply enhanced gravity and flotation. It should be noted that the process developed addresses the critical issue of environmental costs which should be more than enough to justify the shift from the current to the novel and sustainable technologies."

Jan 1, 2014

By J. C. Moreno, G. Rios, M. Palacios

The Huelva smelter was commissioned in 1970 coinciding with the shutdown of the old smelter in the Rio Tinto mine site. That new smelter consisted of two Momoda blast furnaces with a capacity of 500 dmtpd of concentrate. Nevertheless, soon after their start-up, it was clear that an increase in the smelting capacity was needed. After an analysis of the existing alternatives at that time, the flash smelting technology was chosen. The new Outokumpu Flash Smelting Furnace (FSF) came into operation on 18 September1975, with an initial capacity of 900 dmtpd of concentrate, using four Venturi-type burners and preheated atmospheric air. Since that date the Huelva Smelter team, together with Outokumpu (now called Outotec), have continuously improved our FSF design, process conditions and operational practices, leading to a present capacity of 3,500 dmtpd of concentrate. Since 1975, five smelting campaigns have been completed, the last ending in November 2013 with the rebuilding of the original FSF hearth. This paper describes the history of these improvements and the lessons learned.

Jan 1, 2014

By Andre Krzysik

"Fluidized bed technology has been used in the industry for almost 100 years. To fully understand the process hundreds if not thousands of researchers were and are involved in finding the way to predict the behavior of the solids when subjected to the flow of media through them and the conditions of the solids in the fluidized state. The difficulties in predicting the behavior of solids in the fluidized state stem from the complexity and abnormality of the parameters related to the solid particles. Theoretical calculations can in some degree account for some of them. Particle size distribution, their shape, density, moisture content and physical and chemical reaction that may exist in the fluidized bed reactor play an extremely important role and influence the behavior of the fluidized bed. This paper focuses on the practical examples of the fluid bed equipment and the use of different conditions to process various products.IntroductionEach process application has its own unique requirements and the designers of the equipment must take into consideration specific process requirements, specific properties of the material to be processed (both physical and chemical), and physical and chemical reactions/changes that are taking place in the reactor (heat and mass exchange, chemical reactions, isomorphic change etc.). Each individual piece of equipment must also satisfy specific requirements/ preferences of the client that will operate and maintain the equipment. Those often represent greater challenges than the process on its own, and are equally important to the satisfactory operation of the plant. That includes aspects like location of the equipment, environmental effects, and expected life of the equipment, process control, access, maintenance, and many others.Over the period of time a great deal of research, both theoretical and practical have been carried out and the results of that work are available for equipment designers. For the simple applications that information is usually sufficient and the selection of a suitable solution is relatively simple. In many instances, the available information is not sufficient, and often specialized test work needs to be conducted to obtain additional data. In many cases a pilot installation is built in which the required process is tested. Only then the commercial equipment is designed. The following deal with specific installations that were designed to satisfy specific requirements. In some instances, additional problems were discovered during the commissioning of the equipment that required on site modification. The continuous monitoring of the equipment that was supplied to the various clients allowed us to further develop and improve our designs."

Jan 1, 2014

By Wei Wang

The SMCO copper plant is located in DR Congo, and was designed by China NERIN Engineering Co., Ltd. The process is a typical hydrometallurgical plant with Leach-SX-EW, with the project treating the oxide minerals with agitation leaching, followed with three stage of solvent extraction and two stages of stripping, and using permanent SS cathodes to produce LME grade copper. Because of the special characteristic of the ore, what contains 2 different type of oxides (one high carbonate oxide and the other low carbonate), there are several new technical measures that have been developed and adopted for the plant. For example, different grinding, leaching, and filtering are used to treat different oxides. This paper, presents the project process, engineering design, construction and commissioning. The paper also describes some of the problems encountered during plant commissioning, such as the agitation leaching tank issues, and corrosion in the settler-mixer. This paper discusses some NERIN solutions to these problems, and explains the use of the CN filter, which is used to filter PLS to treat high level suspend solids, instead of the traditional sand filter. Finally, this paper also proposes steps / measures for further improvement for future plant operation.

Jan 1, 2014

By Jin Duan, Qi Zheng, Bo Yan, Li-cheng Ma, Xiao-kui Che

"The aim of this study was to develop an approach for the selectively removal of Zn(II) from heavy metal-bearing-wastewaters produced by gold chemical industry using magnetic chitosan based adsorbents. Chitosan beads were prepared by cross-linked modification of Fe3O4-chitosan bead using epichlorohydrin as the cross-linker. Both Zn(II) inprinted magnetic chitosan hydrogel bead (Zn-MCHB) and unprinted magnetic chitosan hydrogel bead (MCHB) were prepared and batch adsorption experiments were used to evaluate their adsorption capacities and selectivities. Single adsorption of Cu2+, Pb2+, Zn2+ and Ni2+ showed that both MCHB and Zn-MCHB adsorbs all the four metals and had an affinity in the order of Cu2+ > Pb2+ > Zn2+ > Ni2+. The binary adsorption revealed that the two adsorbents preferentially adsorb Cu2+/Pb2+ from Zn2+-Cu2+/ Zn2+-Pb2+ binary systems. However, MCHB does not show any selectivity in Zn2+-Ni2+ system. In contrast, Zn- MCHB preferentially adsorbs Zn2+ from Zn2+-Ni2+ binary system. Furthermore, the adsorption selectivity is predictable from stability constants of the metals with the amino group of chitosan. The information revealed in this work can be used for further applications in the treatment of wastewater containing a range of heavy metals from the gold chemical industry."

Jan 1, 2014

"TREVIICOS CorporationINTRODUCTIONThe Walter F. George lock and dam was constructed on the Chattahoochee River between 1955 and 1963 with the double function of improving navigation and generating power. Its 82 ft. by 450 ft. (25m x 137m) lock can accommodate large barge traffic and its four generating units with a plant capacity of 150 MW have an average energy output of 453,000 MWH. The dam consists of a 1,496 ft. (456m) long concrete structure housing the spillway, a non overflow portion, the power units and two earthen wing dams extending to the Georgia and Alabama sides, respectively 5,810 feet and 6,130 feet long (1770m and 1868m). As soon as the reservoir was impounded it became apparent that excessive seepage was occurring. From 1962 to 1985 a series of remedial works was performed using several techniques, but the problems continued under the dam, jeopardizing its generating potential and possibly undermining its stability.Finally, the decision was made to construct a deep cutoff primarily under the concrete portion of the dam to remedy the problem. PROCUREMENTOn July 5th, 2001 best and final offers were solicited by the Corps of Engineers (COE) for the construction of a deep cut-off to be built in front of the concrete portion of the dam from the bottom of the lake and tied into it. The cut-off had to cross an existing lock structure and an underwater retaining wall, as well as the remnants of a steel coffer cell left in place from the initial construction.The specifications required that the wall be built with a minimum thickness of 24” (600mm) and that it extended from the bottom of the lake to elevation -5 (1.52m) into the Providence formation, an impervious layer.While the land portions of the wall were on average 208 feet (63.4m) deep, the marine portion started from up to 90 feet (27m) of water and continued through different rock formations for another 100 feet (30m).Contractors were invited to propose their own method of constructing the cut-off and offers would be evaluated using several criteria, including technical, economical, organizational and experience.Three proposals were received and on August 14, 2001 an award was made to the Joint Venture (JV) of Treviicos and Rodio."

Jan 1, 2014

By Rusty Winn

"R.E. Janes Gravel Co. is an aggregates producer is located along a paleo-channel of the Ogallala formation (locally known as the Slaton Channel) approximately 48.3 km (30 miles) southeast of Lubbock, TX. In an attempt to beneficiate the 25.4-mm (1-in.) concrete aggregate product, a log washer was installed in the processing line to liberate and remove fines (clay) from the finished product. The introduction of this extra cleaning step increased fines in the finished product, exacerbating the original problem. Several other processing options were investigated before a geological analysis was undertaken to try and define the lithology of the formation and formation characteristics in an attempt to alleviate this problem.Initial assessmentsThe mined resources are mid-Miocene to early Pliocene (16-4 mya) in age and is the eastern exposure of the Ogallala formation of the Southern High Plains escarpment. The Ogallala formation consists of coarse-grained alluvial sediments in paleovalley channel ways from the Rocky Mountains with fine Aeolian and paleosol deposition on the uplands across the High Plains region of the United States. Locally, these Rocky Mountain sediments from New Mexico were transported and deposited in a paleochannel that is approximately 0.805 km (0.5 miles) wide and 15.25 to 18.3 m (50 to 60 ft) in depth. As this channel cut across the Southern High Plains it eroded local rock sources of Late Cretaceous limestones and Triassic sandstones and mudstones incorporating them into the younger Ogallala depositional sequence.Depositional historyThe channel currently being mined is a nontypical Ogallala deposit. The Ogallala in the panhandle of Texas is divided into two units, the Couch and the Bridwell. The Couch is the older of the two and exhibits alluvial sedimentation of thicker and larger gravel (up to 76.2 mm or 3 in.) deposits fining upward to Aeolian sedimentation and thick friable caliche deposits. The Bridwell overlies the Couch and is characterized by alluvial sedimentation, a distinctive red tint and smaller gravel components (typically no larger than 25.4 mm or 1 in.) fining upward to Aeolian sedimentation and thick, well-indurated caliche cap. The Slaton Channel divides these two units and shares lithologic components of both, yet is lithologically distinct due to its Cretaceous Age limestone gravels that can be < 3.66 m (12 ft) in size. Caliche/calcrete is a calcareous (CaCO3) deposit that forms in the B horizon of soils as a rain water leachate of CaCO3 from the upper A horizon."

Jan 1, 2014

By J. B. Yianatos

A practical an interactive model to describe the operation of a flotation bank of mechanical cells was developed based on the hydrodynamic and metallurgical characterization of large industrial flotation cells. Thus, the mineral grade and recovery, as well as the stream properties along the flotation bank can be described in terms of the operating variables. The model was built considering the flotation bank as a distributed system, so the solution for the water and solids mass balances, per size classes, for each single cell, are sequentially solved. Also, each cell was described by two distinct zones, the collection zone characterized by the flotation rate constant and the froth zone characterized by the froth recovery. The mineral feed was described in terms of the mineral species and particle size classes, using a rectangular flotation rate constant distribution. Also, the effect of changing the actual operating variables (air flowrate, pulp level, pulp density, pulp flowrate, etc.) on the mineral collection process, in the collection (pulp) zone, was considered downstream along the bank. The froth recovery of floatable mineral has been estimated by measuring the mass flowrate of particles entering the froth by true flotation together with the concentrate mass flowrate (ton/h). The mass flowrate of collected particles at the pulp/froth interface level was calculated from direct measurement of bubble load (ton/m3) and gas flowrate (m3/h). Flotation recovery is mainly related to the froth depth and air flowrate. All parameters considered in the model have been adjusted from direct measurements in plant site. Also, the effects of other operating variables such as reagents dosage, top of froth grade, or froth discharge velocity are presently under study. This procedure has been tested using data from industrial rougher operations consisting of flotation banks with 5 cells to 9 cells in series, and different cell sizes, such as 45m3, 130m3, 160m3 and 250m3. Thus, it has been shown that the model approach is a powerful tool for flotation cells diagnosis, operation and development of new control strategies, as well as, to evaluate the effect that de-sign and operating variables have upon the collection and froth zones performance in large flotation cells.

Jan 1, 2014

By Felipe Costa Hashimoto Bertin, Jorge Alberto Soares Tenório, Rodrigo de Souza Dalti Pereira, Denise Crocce Romano Espinosa

"The increasing amount of portable devices and their fast obsolescence generates an increasing quantity of discarded batteries. The recycling process of discarded batteries allows the recovery of metals for further use and avoids the contamination of soil and water. Even though there are several researches on the topic, few papers focus on mixed batteries. The purpose of this work is to characterize a mass of collected mixed batteries and study the hydrometallurgical process of recycling. The specific leaching parameters studied were pH, temperature and reduction potential. The specific goal was testing the selectivity of pH for leaching each metal. The results show that the optimal leaching occurs in acid solutions with negative pH at IM of sulfuric acid and at room temperature (25°C).IntroductionThe increasing portability of electronic devices in the past century along with their fast obsolescence produce tons of discarded materials yearly that could be recycled generating new materials for the industry. For example, metals such as cobalt and nickel, that are worth respectively US$ 30.00 and US$ 16.10 per kilogram[l,2] are disposed in urban trash yearly, which means that millions of dollars are thrown away instead of being recovered and reused[3].Besides the obvious fact that the society is throwing money away, most of these metals are toxic for the environment and all mammals, so when badly stored after use they can be found contaminating ground water which will contaminate the entire lifecycle. Some of these metals can cause cancer, serious lung problems and have bioaccumulative properties [4] resulting in lower productions of natural products and maybe death for consumers.So in compliance to new regulations such as the National Solid Residue Politic (PNRS) and the CONAMA-Resolution N°401 from November of 2008[5]- (that follows similar restrictions and regulations as the European directives) all those urban and electronic wastes need to be correctly disposed and treated before being thrown away on local dump sites.In Brazil the national rate of garbage recovery is around 70%, which only 5% is properly recycled, accordingly to the research of the UFSC, also electronic waste grows at 5% per year [6]The present study was motivated by the fact that recycling processes for batteries are not spread through the country and by the fact that most papers do not try to recycle a mixed mass of batteries, but a specific mixture which does not represent the composition of traditional household wastes."

Jan 1, 2014

By J. Faitli

The Lake Balaton is the biggest and for many reasons the most important lake in Hungary. To preserve its healthy nature it is necessary to remove the accumulated mud time to time, similarly to the many living waters, lakes and rivers everywhere. Typical existing technologies (mechanical, hydraulic) require large depositional areas, where the removed slurry and mud is dewatered through very long time. One problem is the non existence of an economical mud thickening technology. Another major problem is that current methods remove the sand fraction with the mud as well. Many times sand has to be complemented from outer sources to endanger the natural balance of the living water. By the financial support of the NKFP 3A/068/2004 Hungarian Research Project our consortium has been looking for the solution to the above mentioned problems. The original ideas of the project were: 1. Sand should be separated and returned to the water by hydrocyclon; 2. New mud thickener should be developed based on the principle that vibrating rods can force settling and packing of mud particles. The work was started by fundamental research with different samples from Lake Balaton and River Bodrog. An automated settling column (45L) has been built for the investigation of the effect of vibrating rods on the settling behavior of suspensions. An optical sensor has been developed by with the settling curve (height of settling slurry as function of time) can be automatically measured. Different vibrating methods and parameters have been tested by the application of a linear motor and mechanical eccentric drive. On the basis of the fundamental research a new thickener, called the rod ? lamella thickener has been developed and an industrial size (50m3/h) mud removing technology has been built. Main parts of the technology are the traditional dredging barge and the thickening technology. The thickening and sand separation technology is tugged by the dredging ship. Its main elements are the homogenization tank, slurry pump, hydrocyclon and the rod ? lamella thickener. In this unit lamellas carry out pre-thickening, then vibrating rods further increase the concentration. The thickened mud is transported out by a screw - of which revolution number is precisely controlled - against a spring supported valve. Paper reports about the design, building, water probe and on-site tests of this mud removing technology. Two new patents had been presented, one is about the rod ? lamella thickener and the other is about the mud removing technology with sand separation.

Jan 1, 2014

By E. Gock

Based on the scientific investigations on mechanochemical synthesis of metal sulphides from metals or metal compounds and sulphur or sulphur compounds, the article describes the industrial production of nanoscale metal sulphides. Special operational conditions such as inert atmosphere, size and type of the grinding balls, grinding time and specific energy input are taken into consideration. A system configuration for the manufacturing of sulphides at a capacity of 100 kg/h is presented.

Jan 1, 2014

By H. Ding

Calcium carbonate/Titanium dioxide composite, characterized by coating TiO2 on the surface of CaCO3 particles, is an important substitute for titanium dioxide. This paper studies preparation method of CaCO3/TiO2 ,composites based on mechano-chemical effects, measures its properties as a pigment, analyzes the binding form and interface reaction mechanism between CaCO3 and TiO2. Through single finely grinding of CaCO3, co-grinding of CaCO3 together with TiO2, and mecha-no-chemical effects produced in the course of grinding, CaCO3/TiO2 composites can be prepared successfully. Results indicate that grinding fineness of CaCO3, co-grinding time of CaCO3 and TiO2, the weight ratio of grinding media to mineral feeding, and the amount of TiO2 have much influence on the properties of CaCO3/TiO2 composites. CaCO3/TiO2 composites have the properties same as titanium dioxide pigment, oil adsorption and ultraviolet adsorption same as TiO2, and 90% of hiding power as that of TiO2. Wet grinding of CaCO3 causes the production of mechano-chemical effect and hydroxyl group, through which CaCO3 and TiO2 can be bonded together. Repulsion occurs between the particles of CaCO3 and the particles of TiO2, respectively, they are both in good dispersion. But attraction occurs between CaCO3 and TiO2. TiO2 particles are distributed evenly on the surface of CaCO3. Therefore, coating of TiO2 on the surface of CaCO3 particles and chemical bond between them make CaCO3/TiO2 compo-sites have pigment properties of Titanium.

Jan 1, 2014