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By Gregory Harbort, Sarah K. DeBono, Alan J. Monaghan, Emmanual V. Manlapig

"The Jameson Cell is a type of flotation machine in which air and pulp are brought together in a vertical tube called a downcomer. Within the downcomer the air and pulp are dispersed into a dense foam of fine bubbles, which creates a favourable environment for bubble-particle collision and subsequent collection of hydrophobic particles. The intense collection zone within the downcomer can be considered similar to the zone between the rotor and stator in mechanical flotation cells.Research into the bubble-particle collision and fluid dynamics of mechanical cells rotor-stator zone has been limited by the difficulty of achieving accurate measurements in production sized machines. With the Jameson Cell the downcomer is largely external and separated from the flotation tank, allowing ready access to the primary contacting zone for measurement and analysis.An investigation has been undertaken into the operating characteristics of the downcomer relating to bubble-particle collision. An effective mapping of the downcomer has been made through measurements of void fraction and bubble size taken across cross sections of the downcomer. Analysis of these measurements has provided an interpretation of the variations in the air and fluid dynamics, bubble size and distribution throughout the downcomer chamber.Existing models of bubble-particle collision efficiency are reviewed in respect to the collected information and refinements conducted. The area of maximum bubble-particle collision efficiency is defined. Findings are related to operation within the rotor-stator zone of mechanical flotation cells."

Jan 1, 2003

By Rodrigo Carvalho, Marcelo Tavares

"The accurate prediction of the outcomes in SAG grinding has been a great challenge to researchers and process operators. The use of Discrete Element Methods for modelling charge motion in tumbling mills allowed extraction of not only visual data, such as the position of the charge, but also the energy transfer in terms of the energy dissipated in the collisions. One of the advantages of DEM technique is its scalability to different mill sizes and some operational conditions such as speed and mill filling. Recently the Authors proposed the coupling between DEM outputs and modified Population Balance Models that with proper dedicated ore characterization tests allows the prediction of the outcomes of an energy transfer example. This modelling framework is called the Multi-scale Mechanistic Modelling. This paper shows the application of the Multi-scale Mechanistic Model to a set of pilot plant tests ran at different operational conditions. The prediction of the grinding outcomes and even the stabilization of the charge was achieved by the use of the Multi-scale Mechanistic Modelling framework. This approach has a great potential to become a powerful tool to design and optimize AG and SAG mills."

Jan 1, 2014

Opportunities to monitor and control primary grinding mill performance are strongly sought after in the mineral processing industry. Currently, limited on-line information about mill charge motion and content is available to mill operations for control purposes, leading to periods of lower throughput, instability, variable product size and accelerated mill liner and lifter wear. In response to this need, CSIRO has developed an on-line surface vibration monitor for primary grinding mills which produces data that has been shown to provide new information about the mill charge in terms of toe and shoulder position, as well as potentially key features such as the overall charge level, the distribution between rock and balls in the mill, and the impact of the charge on the mill liners and lifters. This paper outlines the key features of the on-line monitor system, particularly those relating to data transmission, data analysis, and the design of the monitor and its independent power supply. It describes the coupling of single vibration sensor data from the CSIRO on-line monitor to the actual operating conditions of a SAG mill and how the vibration response and hence mill operating conditions vary as a function of time, including during mill equipment failures such as a broken discharge grate. Opportunities for improved mill control based on the data from the on-line monitor are also discussed, as well as the implications in terms of mill processing and maintenance performance. Recently a CSIRO monitor was also installed on a ROM ball mill and analysis of the vibration sensor data from this installation is currently underway. Preliminary findings from this installation will be presented along with comparisons of generic information, such as toe position (measurement precision and operation variability) and vibration signal (intensity, sensitivity and operation variability), between this type of primary grinding mill and AG/SAG mills.

Sep 1, 2012

By D. W. Fuerstenau

Understanding how cationic surfactants affect the interfacial behavior of quartz is important in mineral processing and environmental engineering. This paper presents the results of a study of the effect of the molecular structure of cationic surfactants on the interfacial behavior of finely ground natural quartz. Most of the experimental work involved the determination of zeta potentials and the stability of quartz suspensions. Some measurements of induction times and the flotation response of coarser particles are also included. How these surfactants affect interfacial behavior is discussed in terms of adsorption mechanisms. The molecular structure (number of hydrocarbon chains, type of ionic head group, number of ionic head groups on the molecule) of these reagents was found to significantly affect their surface activity.

Jan 1, 2014

By D. G. Hulbert

"Mineral processes are complex operations that have been modelled, controlled and simulated by diverse technologies. A review is given of some models of mineral processes in the literature. A new variation of a dynamic process model of flotation is presented. Process models, describing real and relevant physical variables, give a good understanding and good qualitative simulations, but can sometimes require prohibitively difficult and extensive parameter estimations. Process control is usually best done on operational plants by the fitting of system models, which can home in on the plant?s observability, controllability and optimisation. System models can be of a form amenable for use in appropriate techniques for controller design and implementation. The control of milling circuits is discussed in some detail. While simulators use models to predict dynamic or steady-state information, part of their strength lies in their ease of use and their ability to test different types of specifications. Some results are given for a flotation circuit simulator that can be made to solve virtually any permutation of specifications.INTRODUCTIONThe development and application of appropriate technology can lead to better operation of mineral processing plants in industry, so that substantial benefits can be obtained from improved throughputs, efficiencies and product qualities. This paper addresses some of the principles and methods used in the quest for the development and exploitation of such technology. Although the design of processes is often the motivation for modelling and simulation, this paper also targets the use of modelling and simulation for the control and optimum operation of mineral processes. The two processes given the most attention here are flotation and milling.Technologies used in mineral processing range from simple to very complex. Simple technical principles, such as mass and component balances, can yield some simple and effective strategies for modelling and control. However, minerals in particulate form have such complex physical and chemical properties that there appears no end to the complexity that emerges, as more and more factors are taken into consideration in the pursuit of better results and understanding. The situation is aggravated by the complexity of mineral processing plants, which have spatially variable conditions within process units, and complicated interactions between these units."

Jan 1, 2003

By Sung. Hyejin, Kyoungkeun Yoo, Oh-hyeok Kown

The sediments near coasts and ports in Korea have been found to be contaminated with heavy metals and organic matters. So far the sediments have been dumped to landfill sites or ocean. However, the number of available landfill sites is decreasing and ocean disposal of wastes was strictly prohibited. Although physical separation processes have been found to be useful for the remediation of contaminated soil with heavy metals, because the sediments consist of fine particles, it is difficult to remove heavy metal component by physical separation processes. Furthermore, the sediments contain organic matter, so there is a concern about strong stink during the sediment treatment. The present study is aimed to develop the treatment process for removing heavy metals and organic matter from the contaminated sediments. The heavy metals and organic matter were oxidized and dissolved by electro-generated chlorine, and the chlorine used is regenerated and circulated in the leaching process. This system has economic and environmental advantages to reduce the wastewater and the oxidant consumption. The leaching results show that the metal removal efficiency increased to more than 99%, and more than 50% of organic matter was decomposed.

Jan 1, 2014

By Leon Lorenzen, Trevor J. Britz, Pierre J. Van Zyl, Ellis R. Els

Enhanced granulation of UASB granules was tested on pilot scale with two different test reactors (about 5 litres capacity each). Sludge from a local sewage works was used, with peach cannery effluent as carbon source. Cyclic motion of the reactor contents, and a daily replenishment of feed material create the necessary stress conditions for enhanced growth. Sizable granules, bigger than 0.5 mm, were produced within 20 days. Of the two reactors tested, the reactor equipped with a horizontal agitation shaft proved more effective.

Jan 1, 2003

By H. J. Liang

In this study, zeta potential and contact angle measurements of pyrite before and after interacting with Thiobacillus ferrooxidans are carried out to investigate the changes in its surface properties. The results show that, after pyrite interacting with Thiobacillus ferrooxidans and its metabolite, the surface electricity of pyrite changes obviously, resulting in a notable shifting of isoelectric point to lower pH value, but the contact angle varies little. Bacterial protein plays the most important role in the interaction. This work is helpful to disclose the mechanisms of Thiobacillus ferrooxidans de-pressing pyrite flotability.

Jan 1, 2014

By M. Amani, A. Akbarinasab, M. Bazmandeh

The fourth iron ore production plant at Golgohar mining and industrial company consists a ball mill and wet medium intensity magnetic separators (3500 Guss). The ball mill product applies directly into MIMS and the MIMS concentrate directly transfers to the low intensity magnet separators (LIMS). The thickener is used for dewatering of MIMS and LIMS tailings. By sampling from streams of ball mill and separators, it was defined that the grade and iron recovery were 60% and 80% respectively while they would be 66% and 90% respectively based on the designing documentation. The average of P80 in the ball mill was 342 micron in a month that is coarser than optimized value. This problem was related to unsuitable operation of grinding. For optimization of grinding efficiency, the amount of charge volume was investigated as a variable. The measurements illustrated 32% charge volume. For increasing grinding efficiency, the charge volume was increased 1% and 1.6% in two stages. The results showed ball mill power draw average reached from 3650 kw to 4120 kw and the average P80 reached to 329 micron. All of parameters calculated about 35 day before and after change. Average of Ball mill feed iron ore grade before and after change was 49.24% and 50.32% respectively. This change caused an increase in efficiency of MIMS, where the enrichment ratio and concentrate grade increased 2% and 1.9% respectively. For increasing the iron grade of the MIMS concentrate; the orifice of the tail flow exit pipe changed from 4 inch to 6 inch and the concentrate grade increased 2%.

Jan 1, 2014

By Yong Liu, Peng Qian, Shu-Feng Ye, Shao-Jun Chu, Pei-Wei Han

"Chromite with a low mass ratio of Cr to Fe (Cr/Fe ratio) was treated by the carbochlorination method using solid chlorinating agent (MgCl2 and CaCl2) and carbon in the present paper. The results showed that iron could be selective removed mainly in the form of FeCl2. The removal of iron was indirectly, which consisted of the decomposition of solid chlorinating agent to release Cl2/HCl and the carbochlorination of FeO•Cr2O3 by Cl2/HCl and C. The Cr/Fe ratio increased as increasing temperature from 700 ? to 900 ? in air atmosphere, while the tendency was opposite in N2 atmosphere. The removal efficiency of iron by CaCl2 was better than that by MgCl2. At last, a new pelletizing process was proposed to treat fine chromite with a low Cr/Fe ratio based on carbochlorination method, which could produce the high quality roasted chromite pellets with higher Cr/Fe ratio and compressive strength. INTRODUCTION Chromite is mainly used for the production of ferrochromium. A high Cr/Fe ratio (>2) of chromite is usually required to meet the technical specification of ferrochromium.(Gasik, 2013) Attentions have been attracted to the economic and efficient methods for the recovery of chromium from lower-grade ores as the higher-grade ores become depleted. However, the Cr/Fe ratio is difficult to improve through the conventional beneficiation methods (such as gravity concentration, flotation) due to the spinel composition, although beneficiation methods could increase the metal content of chromite ores by removing gangues.(Nafziger, 1982) The main industrial mineral of chromite is (Fe,Mg)O•(Cr,Al,Fe)2O3, which belongs to spinel magnetite.(Liu, 2013) Iron should be selectively removed through the structural dissociation of spinel to increase Cr/Fe ratio.(Nafziger, 1982)"

Jan 1, 2018

By W. P. Roux

With depletion of higher grade iron ore reserves, and the need to process finer, lower grade material; there is a need to better understand the recovery efficiency of jigging process. The use of Positron Emission Particle Tracking (PEPT) was examined as a technique, to study the motion of particles inside a laboratory batch jig. PEPT is a noninvasive method that can provide three dimensional kinetic data of a particle during jigging. Particles with different densities and sizes were traced under the same jigging parameters, to obtain a data set that can be used for the development and verification of jigging models. From the results, detailed information on the stratification rate of a particle was obtained, with adequate resolution to see particle movement through an individual pulse. Detailed data of this nature is critical for the validation of CFD and DEM models. Keywords: positron emission particle tracking, jigging, jig models

Sep 1, 2012

By A. Gueciouer, A. Akkouche, K. Chalah, A. Benmounah

"Drilling solid waste is a typical industrial solid waste, and it is a major pollutant source to ecological environment. Generally, waste management dewatering systems separate solids and fine particles from the liquid phase of drilling fluid, thereby leaving a clarified aqueous solution and allow the cleaning of waste fluids. Typically, dewatering waste management systems clean drilling fluid through coagulation, flocculation and/or mechanical separation. Chemicals used in dewatering are based on the coagulation-flocculation process, which it facilitate the removal of suspended solids and colloidal particles. The factors which can promote the coagulation-flocculation are velocity gradient, contact time, and PH. The objective of this work is to optimize a formulation adequate for dewatering based on the coagulation-flocculation process used coagulant (Aluminum sulphate), anionic flocculants (Partially Hydrolyzed Polyacrylamide) and anionic polyelectrolytes (in solid form with linear chain with very high molecular weight). The results obtained show the good efficiency of the coagulant and flocculants. INTRODUCTION Rig site dewatering of drilling fluids with recycling of processed water can help an operator to comply with environmental rules by reducing volumes of waste and reducing long term liabilities. It can also reduce disposal costs and provide a cleaner drill site overall. Most of the environmental concerns during the 1980s involved hazardous materials and toxic wastes. Drilling fluids, many of which are chemically benign, have escaped many of the difficult-to-comply-with rules and regulations. During the 1990s, however, operators may be required to submit a written plan for liquid waste reduction for even nonhazardous materials. Many states and local agencies may institute total bans on oil field wastes. Drilling rigs typically produce about 1 bbl of liquid waste for every 1 ft of hole drilled. Thus, a typical drilling operation can produce a large quantity of waste [1]. To improve the dewaterability of sludge, different pretreatment processes have been widely studied and developed including thermal, chemical, magnetic, mechanical, acoustic, electric, electro-acoustic and their hybrid treatment processes [2]. Rig site dewatering (figure 1) is the process of injecting coagulants or flocculating chemicals into the mud entering a large clarifying centrifuge. Coagulation occurs when the solid and allowing it to be attracted to other solids by van der waals forces. Flocculation is the binding of individual solid particles into aggregates of multiple particles. It is physical, rather than electrical, and occurs when one segment of a flocculating polymer chain absorbs simultaneously onto more than one particle [3]."

Jan 1, 2018

By Y. M. Zhu

Lead in environment often causes a serious health hazard. The removal of Pb2+ from aqueous phase is a beneficial project. In this paper, deposited Saccharomyces cerevisiae (S.c.) was chosen as adsorbent, Pb2+ ions as adsorbate, and the process of biosorption was studied. The dynamics of the adsorption was investigated. The adsorption mechanism of Pb2+ by S.c. cells was also investigated by detecting microstructure, zeta potential under different pH value, FT-IR spectra of the S.c. particles before and after biosorption. It was shown that the biosorption of Pb2+ by deposited S. c. is a rapid process, and the adsorbing equilibrium is reached within 10 minutes. The Zero point of zeta potential of S.c. cells is pH=3.3. When 2.0<pH<3.3, there exists biosorption (biosorption rate 76%~88%), which means static bio-sorption been not the only kind of biosorption. FT-IR spectrum analysis showed that groups on bacteria surface were mainly characteristic groups of protein and amylase; oxo-groups and nitric-groups on S.c. cell surface could chelate with heavy metal ions. Chemical adsorption might exist in the process.

Jan 1, 2014

By Zhou Yucai, Zhou Jing, Zhu Yimim

"In this article, research on the beneficiation process for a carbon containing copper-molybdenum deposit in Henan province has been carried out. The elemental composition, mineral composition and relative content, characteristics of embedded and symbiotic relationship, the forms of the copper-molybdenum particlesand their disseminated features, and particle size distribution have been worked out. Flotation behavior of copper-molybdenum mixed flotation and separate flotation in the systems of different collectors and depressants, and the influence of different flowsheets on the copper-molybdenum separation have been investigated by actual ore flotation tests, The separation problem of copper-molybdenum for a carbon-containing copper molybdenum ore has been solved.INTRODUCTION In this paper, technological mineralogy, small experiment of flotation recovery of copper Molybdenum ore, and expansion experiment of mineral recovery of copper Molybdenum ore are introduced. (1) The results of process mineralogyshow that the content of copper is 0.42%, molybdenum is 0.021% in the raw ore, they mainly exist in the form of sulfide, with low oxidation rate. (2) The results of flotation tests show that the combination of butyl xanthate and isopropyl ethylthionocarbamate reagents is effective collector of copper-molybdenum mixed flotation for carbon copper molybdenum, (3) When the grinding fineness is -0.074 mm taking 71%, and regrinding fineness is -0.038 mm taking 85%, the flowsheet of first copper-molybdenum mixed flotation and then regrinding rough concentrate and last separation flotation of copper and molybdenum was adopted, which realized the effective separation of copper and molybdenum for carbon-containing copper molybdenum ore. Good flotation indexes were gained with copper concentrate containing 20.96% copper and copper recovery 90.06%, and molybdenum concentrate containing 46.78% molybdenum with molybdenum recovery 72.68%. (4) The seven days average concentration index of scale-up the continuous dressing experiment is as follows, the copper content in copper concentrate is 20.16% and the recovery is 89.61%; the molybdenum content in molybdenum concentrate is 24.58% and the recovery rate is 74.09%."

Jan 1, 2018

By H. Hamza, M. R. MacIver, M. Pawlik, L. Malin

"Size and shape are important properties of aggregates formed in engineering processes and natural systems. Measurement of aggregate size or shape is a challenge when the solids concentration is beyond the gel point, ?? > ??g, when the aggregates are in contact and it is difficult to distinguish or segment individual particles in the network. This paper describes the use of a micro-computed tomography (micro-CT) method for the calculation of the aggregate volume fraction, ??, and a characteristic aggregate length, ??a, based on a 3D chord length measurement algorithm. These parameters can be used to quantify changes in aggregate and pore size during a compressive yield stress test to help understand the impact of flocculation and network structure on dewatering. INTRODUCTION In a thickener, flocculation is often used as a pre-treatment step and the final solids content of the underflow depends on the network strength and permeability of the bed formed by settled aggregates (Usher, Spehar, and Scales 2009). This paper describes the measurement and analysis of micro-computed tomography (micro-CT) of flocculated mineral sediments to obtain a characteristic length, ??a, of the aggregate and pore phases during a staged compressive yield stress experiment. This parameter may be used as an indicator of changes in aggregate and pore size to quantify material behaviour in solid-liquid separation processes that depend on self-weight compression or applied pressure. This analysis was carried out to help understand the effect of flocculation on aggregate structure and the thickening process as part of a broader research on the improved solid liquid separation of tailings produced in the oil sands industry.Aggregate properties The solids phase of an aggregated or flocculated suspension will eventually settle – if left undisturbed – under the influence of gravity. As settling of a flocculated suspension continues, the solids volume concentration, ??, may increase to the gel point or gelation threshold (Landman and White 1994), ??g, above which the aggregates form a network of touching particles, or space-filling structure (Kranenburg 1994). In the sediment bed, the aggregates are surrounded by fluid and occupy a partial volume fraction, ??, according to"

Jan 1, 2018

By M. Pischtschan, S. Belz, M. Perrucci

In High Pressure Grinding Rolls (HPGR), the material grinding takes place between the fixed and floating rollers. In this regard, the rollers start to wear over a period of time, which is impacted by for e.g.: ore characteristics, operating pressure, feed material size and non-uniform feed presentation across the roller width. HPGR operational experiences have shown that the rollers do not wear at the same rate. This differential wear rate over time leads to differences in the tangential speeds of the rollers, causing an uneven gap between the fixed and floating rollers in relation to the material. This unwanted but extremely common situation results in a less effective grinding process due to the fact that the slip between rollers is not optimal. As the rollers wear profile increases, the roller with smaller diameter starts to wear further, deteriorating the comminution efficiency up to a point where operators have to stop the HPGR to replace the rollers. Since the wear rate of the rollers is not equal, the replacement of the same cannot be properly planned so that their life-time are fully utilized. In this paper, a dynamic load share control with the use of ABB’s variable speed drive system is proposed, which provides the possibility to the HPGR operator to impact the roller wear in such a way that it equalizes the wear rate to a certain extent and extends the roller life time. Called RollXtend™, this solution includes a load share factor which can be parameterized based on the wear measurement performed manually during maintenance procedure. Additionally, this paper describes an automated load sharing concept based on a non-invasive wear measurement method. The partial results of the technology trial in a copper/gold mine are presented, which aimed at detecting stud damage and estimating the real rollers profile throughout their life time. The final objective of the pilot project was reduce the amount of planned and unplanned downtimes of the HPGR by increasing the rollers life time and avoiding catastrophic stud damages.

Jan 1, 2018

By C. Gomez, J. Finch, R. Dalhke, J. Torrealba-Vargas

The velocity of gas passing through a flotation cell can be estimated by collecting bubbles by natural buoyancy in a closed tube and measuring the rate of pressure increase. The governing equation is derived and verified. Single- and two-tube gas velocity sensors are described. The latter design permits a correction for bulk density and level change during signal collection.

Jan 1, 2003

By Yu. Gurevich, M. Teremova, I. Prokopev, A. Razvjaznaya, N. Algebraistova

"The objective of this work is the scientific justification and development of efficient and environmentally-friendly method of bulk concentrate preparation for selection with application of microbiological practices. This research suggests to apply Pseudomonas Japonica bacterial culture to the bulk concentrate before the selection circuit in order to clear the surface of sulphides from the xanthate skin. It is also suggested to apply bacterial consortium Ochrobactrum ?nthropi and Pseudomonas aeruginosa JCM 5962 for desorption of diesel residual concentrations. High-efficient and environmentally friendly method of copper-molybdene and lead-zinc bulk concentrate selection was developed based on theoretical and experimental research work with application of microbiological practices. In comparison with conventional methods (steaming, sodium sulphide washing) the above suggested bio-technological method of bulk concentrate preparation before selection cycle will allow to reduce material and power expenditures, and it is also environmentally friendly. INTRODUCTION High-efficient selection of sulphide bulk concentrate is gained exclusively after collecting agent is removed from mineral surface. Therefore, the problem of bulk concentrate preparing before the selection cycle is acute, since the further technological parameters of the subsequent separation depends on the effectiveness of pulp preparation. Existing traditional ways of bulk concentrate preparation. such as washing or steaming, are characterized by high energy and material costs in industrial conditions [1,2]. The microbiological treatment before separation of the bulk concentrate into different kind of concentrates appear one of perspective processes for treatment of bulk concentrates [3,4]. At the present time, the world practice of processing mineral raw materials demonstrates the wide application of technologies using microorganisms: bacterial leaching and oxidation, purification of industrial wastewater. This is due to the fact that biotechnological methods are environmentally safe, low-cost, and suitable for refining complex ores and raw materials of industrial origin."

Jan 1, 2018

By H. Mengbing, A. Potokin, A. Usov

"Revealed and analyzed in the study are the ways of significant perfection of specific characteristics of the equipment, such as use of high-frequency voltage transformation to create a charger; use of pulse transformers, with core made of materials with high magnetic permeability, in pulse generating circuits; as well as use of special ways to produce voltage pulses with a short front. The experiments have proved the possibility to adapt these technological solutions for electric-pulse installations, and suggested on this base is a strategy of further development and application of electric-pulse technologies. The different applications joint work schemes of voltage sources with two levels voltage and energy in electric pulse technologies are investigated. The possibility of increasing energy efficiency of destruction is shown."

Jan 1, 2014

By A. Y. Senchenko, Y. V. Kulikov

"The most common technique for selection of grinding equipment is the Bond method implying determination of a ball mill work index (BWi). The method is perfect for greenfield projects where a ball mill must be sized to grind an ore to 80% passing 75-100 µm. Finer grinding will require application of specific correction factors to a standard equation since initially the method was not designated for sizing of fine (minus 75 µm) grinding mills. Significant issues are related to selection of grinding equipment for treatment of originally fine materials when the standard procedure is not applicable. In 1984, Levin published his special technique titled as “A proposed test for the determination of the grindability of fine materials”, where he offered to use the standard Bond ball mill for determination of a specific grinding energy. However, this method did not meet with wide recognition. In 2017, Institute TOMS under guidance of JKMRC’s specialists performed a testwork aimed at verification of a new universal technique for determination of grindability of initially fine materials. An object was to test three aged tailings samples for the subsequent modelling of comminution circuit and evaluation of potential throughput of the existing ball mills with final grind size of ?80 passing 53 µm. In parallel with development of the universal approach, TOMS’ specialists carried out tests according to the Levin method in order to compare the data resulted from two methods. The results from lab ball mill testing on three products following the alternative test methods are presented in this paper along with the testing methodology and results analysis. Specific energy was calculated for regrinding of the materials to the required size. Difference of the examined methods and assessment of their applicability for sizing of full-scale equipment are explored."

Jan 1, 2018