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By Apoorva Bajaj

Iron ore mines of Steel Authority of India Limited (SAIL) have to comply with strict chemical composition norms laid down for iron ore lumps supplied to its steel plants. This requires a careful planning of the overall ore excavation operation. In general terms, the problem can be stated as: Given the chemical composition of ore for all excavation sites, excavation capacity of each shovel, distance of each excavation site from the crushing plant and the number of dumpers available for transport of the ore, find out the percentage of ore to be excavated from each excavation site such that the production rate is maximized and the chemical composition norm is satisfied to the best possible extent. This paper presents an approach to solve this problem using Branch and Bound method. The specification for r.o.m. quality has been modified by incorporating a new parameter, ?Al2O3 / SiO2? ratio, which has a significant effect on the performance of iron blast furnace.

Oct 1, 2009

By Shintaro Takamiya, Kazunari Yoshida

"Recently, small sized micro-needles for medical are required more frequently by patients. The biggest reason is that it presents great burden on the patients, due to the size of the needle injection. People need to use a very small needle to lower the pain, but the downfall is that it makes them more expensive due to their complicated manufacturing method. Therefore, we need to fabricate a needle by wire-drawing to decrease its price. Tube-drawing is beneficial for its production value; however, in conventional tube-drawing it is difficult of control the wall thickness of the tube and makes it 1mmor lower in diameter. That is why, we propose fluid-mandrel drawing for new tube drawing. This method allows fabrication of a fine tube by using the pressure of the fluid in the tube. In this research, the goal is the fabrication of a fine tube by fluid-mandrel drawing and its evaluation. Finally, the fabrication of a fine tube by fluid-mandrel drawing was conducted and in result a tube with a diameter of 0.2mm, high strength and thin wall and fine inner surface was drawn, which can be used as a lesser pain micro-needle.INTRODUCTIONThe main manufacturing method of the current medical needles is roll forming. With this method, it is difficult to make a tube with a diameter lower than 1mm. Deep drawing has been proposed and used as method to further reduce the diameter, but this method is costly and the injection needle obtained by this method is several times more expensive.Therefore, we need to obtain a fine medical needle by drawing process that can be mass-produced and inexpensively manufactured. However, with the conventional drawing process, it is not possible to obtain a syringe needle with a reduced diameter easily, that is why, a fluid-mandrel drawing has been proposed which can reduce the diameter without damaging the inner surface. The methodology of the method is, a fluid is filled in the sealed tube and the pressure inside the tube during drawing is responsible for the good inner surface and wall thickness. It is also expected that the fluid can be easily discarded and that the tube can be manufactured on a long scale."

Jan 1, 2017

By R. Mulligan

"The Cordilleran tin belt extends from the Seward Peninsula in westernmost Alaska to Mexico. Throughout the Canadian section, tin occurrences are mainly confined to a belt along the northeastern fringe of the Western Cordilleran sub-region; the boundary of this sub-region with the Eastern Cordilleran sub-region is most simply defined as the practical eastern limit of granitic and metamorphic rocks. The stratified rocks underlying this restricted belt are mainly late Precambrian and early Paleozoic miogeosynclinal sedimentary rocks, which are more or less metamorphosed but otherwise are generally equivalent to the less severely deformed rocks underlying the Eastern Cordilleran sub-region. They contrast with Late Paleozoic - Mesozoic eugeosynclinal volcanic-sedimentary assemblages farther west, but the granitic intrusions throughout are mainly of Late Mesozoic age. Thus, narrowly defined, the tin belt largely coincides with a lead-zinc-silver metallogenic province, whereas copper deposits characterize the eugeosynclinal regions to the west. In addition to the tin occurrences, which include the Sullivan lead-zinc-silver mine, Canada's only significant producer, the belt contains all the beryllium, most of the tungsten and many Iithophile-type molybdenum occurrences. Several types of occurrences of each metal are represented. Lithium occurrences in the Canadian Cordillera are notably rare, and these few are insignificant."

Jan 1, 1971

By J P. Bolduc, P. E. Pelletier

Preceded by brief general considerations such as the development of the mining industry in. the Province of Quebec, the choice of plant location, the types of problems studied etc., the paper gives a complete description of this new research and treatment center for metallic, non-metallic and asbestos ores. Facilities for carrying out operations in the three sections of the plant -the sampling section, the ore treatment section and the asbestos section -are fully discussed as well as laboratory facilities for (a) the preliminary testing of ores prior to pilot plant treatment and (b) the grading and testing of asbestos fibre. AT THE beginning of the century, the annual value of the mineral production of the Province of Quebec stood at the $2,500,000 level. Twenty-five years later, it was just under $24,000,000. In 1950, half a century later, it was slightly in excess of $200,000,000. But in 1959, in the span of only nine years, it

Jan 1, 1962

By R. W. Thompkins

In order to evaluate the impact of air quality control on mine design, a few examples are given of cases in wh.ich ventilation has affected the economics of the total design problem. Principles for the drainage of gas contaminants are shown, and the contamination control problems created by differential pressures in complicated booster fan installations are discussed. The paper also deals with the use of advanced mathematics for solving some of the ventilation problems likely to be encountered.

Jan 1, 1967

By Lewis Finch

Oil and .gas reservoirs exist under pressure within the pore spaces of rock structures or traps. Wells are drilled to produce these reservoirs. Under primary operation, the natural energy of expanding fluids in and adjacent to the reservoir forces or drives oil and gas to the wells. There are three basic sources of energy: dissolved gas, water, and gas cap. Typical recovery by primary methods is only 10 to 25 per cent of the oil in place for the dissolved gas drive but is generally higher for the others. Secondary recovery involves the injection of water or gas to supplement natural energy, thereby increasing recovery over that obtainable by primary operation alone. In many cases ultimate recovery with secondary methods is 1.2 to 2.0 times the expected primary recovery. The type programme adaptable in a field depends on its 'primary performance and on certain reservoir characteristics. In the United States, application of secondary recovery methods is becoming increasingly important. About 22 per cent of United States oil production now comes from fields in which injection projects are operating. In 1953, nearly 1.4 million barrels of oil daily came from such fields, more than double the amount in the early 40's. Ultimate primary recovery from known pools is estimated at roughly 73 billion barrels. Secondary recovery projects already in operation will increase this to almost 80 billion, an increase of almost 10 per cent. Unitized secondary recovery projects have been very successful. From unitized projects alone, industry reserves of oil in the United States have been increased by 3 1/2 billion barrels. In Canada, secondary recovery has not been so wide spread mainly because D-3 reef reservoirs which have held the major reserves are under water drive. However, appreciable amounts of water are being injected in the Redwater D-3, Leduc D-2 and Joarcum Viking reservoirs, and gas in the Golden Spike D-3. In both countries, possible achievements in increased recovery through secondary recovery methods now in use and by new ones which may be developed through research and field trial are a challenge to the scientist and the industry.

Jan 1, 1956

By T. Möller

Grinding mills are the heart of the mineral processing plant, and are production-critical machines which are required to achieve high availability. Liner wear life and a liner design that promotes ease of installation are important variables to achieve a high level of mill availability. Increased mill size results in more mill internal surface to protect, and more liner components to install and remove. This drives designers toward an increase in liner size to minimize the number of components to be installed by the liner handler. The liner attachment method can also have a large impact on mill availability as well as safety during installation. This paper outlines the experience from the development, installation and follow-up of liners installed in two 38' x 45' AG Mills at Boliden Aitik in Sweden. A new Poly-Met shell liner concept has been developed to minimize the number of liner components. The new Poly-Met shell liner components are made much larger than conventional Poly-Met or steel liners. This reduces the number of components to be installed/removed by the liner handler and helps to minimize installation time and consequently down- time. A new attachment system has also been developed to eliminate the need for the installation crew to be in the ?drop-zone? of the shell liners while installing the liner bolts. One interesting aspect of this project was the requirement to predict liner life for these new large format AG mills. The existing 22' diameter mills at Aitik provided a base-line reference for this purpose, and DEM studies were used in the project development stage to predict the wear life of shell liners for the new 38' diameter AG mills. The results from this study are included.

Jan 1, 2012

By H. Lazreg

This paper presents an evaluation of surface resistivity techniques as a tool for delineating salt-water intrusion in Shippegan, N.B. The study consisted of resistivity profiling, resistivity soundings and a limited number of induced polarization soundings in selected areas in the Province of New Brunwick. The results from resistivity profiling indicate that when seawater intrusion occurs in a sandstone formation the resistivity contrast is sufficiently large to allow a precise delineation of the intrusion. A formula is then derived to convert resistivity values to chloride concentration in the "cone of intrusion". The results from resistivity soundings showed that shaly formations may have resistivities as low as seawater-contaminated sandstone. An indeterminacy has resulted from this resistivity overlap. A limited number of IP soundings were performed in an effort to resolve it. The results showed that IP can be of appreciable help in resistivity interpretation.

Jan 1, 1972

By Ramin ArameshAsl

Urumieh-Dokhtar is the well-known vast metallogenic belt extended from NW to SE of Iran and basically is referenced in copper mineralization studies in Iran. Hashtjin 1:100000 sheet (NW Iran) is located on this belt and rock units are consisted of Oligocene intrusive, volcanic rocks and Eocene Sedimentary rocks. Concerning the significance of identifying the alterations and faults zones in copper exploration, the aim of this study is identifying the copper mineralization by multi-spectral analysis of ASTER (Advanced Space borne, Thermal Emission and Reflection Radiometer) satellite images in the limitation SD-SWIR (Spectral Domain of Short Wave Infrared). Several analytical methods are implemented in this study such as SAM (Spectral Angle Mapper), MF (Matched Filtering) and PCA (Principal Components Analysis). These methods have been utilized for recognizing the Argillic, Propylitic and Sericitic alteration zones and all of them are relying on the remote sensing methods as well as geological studies of new targets for copper mineralization identification in the area.

Aug 1, 2013

By Kish. L.

"The results of a chemical and mineralogical study of eighteen opaque-oxide occurrences are discussed and the detailed chemical, metallurgical and mining feasibility study of a vanadium-rich magnetite deposit is summarized. A plot of the mol-percentages in the system FeO- Fe2O 3-TiO2 indicates that the deposits fall into two distinct groups: some contain hematite with ilmenite, and some others have magnetite with ilmenite (titaniferous magnetites). The plot also suggests that the two types of deposits were crystallized from liquids of different compositions. Each group has its distinct structural features. Vanadium is present in all of the studied specimens, however concentrations of economic importance have so far been found only in the titaniferous magnetite deposits. The vanadium content of the oxide concentrations of the Dore Lake Complex is the largest among the studied occurrences. Analyses of the concentrates of the drill-core sections show a compositional variation across the orebody; a continuous increase in the tenor of Ti02 and a decrease in the vanadium content upward in the layered sequence is found. Concentration tests on several tons of samples indicate that about 80 per cent of the vanadium is recovered in the magnetite concentrate."

Jan 1, 1972

By D. Atkinson

"Porphyry molybdenum-tungsten mineralization on the east flank of Hudson Bay Mountain crops out over 5 km2 and is intersected to depths of 2 km. Features such as a hornblende-biotite aureole, mineralogical zoning and dike, vein and fracture geometries within lithologies of the Middle to Lower Jurassic Hazelton Group and Cretaceous Skeena Group reflect an intrusive complex, the Upper Cretaceous to Early Tertiary Hudson Bay Mountain stock which has been intersected by drill holes. The stock is believed to be the mineralizing agent. A southeast-dipping granodiorite sill has been outlined by drilling within the Hazelton Group. Molybdenite and scheelite veins cut all rock types; however, the granodiorite sill hosts a higher density of fine-grained, banded, quartz-molybdenite and pegmatitic quartz-molybdenite veins reflecting a competency contrast between the intrusive sill and other country rock. Due to the relative abundance of these veins, grade is higher within areas of the sill. Above the 15000£ cross-cut 20.6 million tonnes grading 0.401% MoS2 and 0.041% W03 have been defined. During exploration of the deposit sampling procedures had to be adjusted because of the nugget effect attributed to drill intersections of banded and pegmatitic veins.IntroductionMolybdenite was discovered in outcrop at the foot of Kathlyn Glacier on Hudson Bay Mountain and first reported by the Geological Survey of Canada in 1944. The deposit has several names: Hudson Bay Mountain or Glacier Gulch, both after its location, and Yorke-Hardy after the original staker.The deposit is on the east flank of Hudson Bay Mountain, 9 km northwest of Smithers, west-central British Columbia, within NTS area 93L/14 (54° 49' North, 127° 18' West, Fig. 1). Hudson Bay Mountain, on the southern edge of the Bulkley Valley, is a dominant topographical feature reaching 2590 m elevation. Mineralization is partly overlain by the Kathyln Glacier which is visible from Highway 16. Access to the 3100 m of underground development is from a portal at 1066 m elevation on the east slope of Hudson Bay Mountain."

Jan 1, 1995

By B. Das

"Computers have been used extensively in the mineral industry in exploration, reserves calculation, mining technology, mineral processing, etc. With respect to coal mining, there are also various applications for evaluating rock slope stability of open pits, design of open pits, underground operations, mine ventilation, ground control, data processing and management information, operations control and certain technological applications. Mine ventilation appears to be the field in underground coal mining touched on most; on the other hand, underground coal mining methods evaluation is represented only sparingly.It is therefore essential to review the status of the computer in underground coal mining methods evaluation in order to define its scope for further application. The paper discusses the roles of the mining engineer, programmer, computer operator and analyst as well as that of the computer. The important parameters will be identified and discussed along with their application for different underground coal mining methods, with their individual unit processes. Mainly, longwall face operations have been covered. Although many models have been of academic interest, they can be considered as important steps in a transition stage which will be followed by more practical applications for computers for underground coal mining method evaluations in the future. This calls for a coordinated effort from all concerned."

Jan 1, 1981

By Y. Mudryk, D. Paudyal, K. A. Gschneidner, V. K. Pecharsky, M. Khan

"Rare earth intermetallic compounds are utilized commercially as magnetic and battery materials, electron gun electrodes, etc. Several of these intermetallics will be briefly discussed. There are many other rare earth intermetallic compounds which are not utilized industrially but have unusual properties which are of fundamental interest and may have future technological applications. Several of these materials are discussed as well.INTRODUCTIONTens of thousands of rare earth intermetallic compounds exist, but physical properties (primarily their magnetic behaviors), other than their crystal structures have been measured for only a small percentage of these materials. Among these are the commercially important compounds: Nd2Fe14B, and the SmCo5 – Sm2Co17 family – well known high strength permanent magnets; (Tb0.3Dy0.7)Fe2, Terfenol-D, a giant magnetostrictive material; LaNi5Hx a critical component of the rechargeable Ni metal hydride batteries; and LaB6 an electron emitter. There are, however, many other intermetallic compounds which are not utilized industrially, but none-the-less, exhibit interesting, and sometimes, exotic physical properties which are of fundamental interest and may have some future technological significance. These include: the giant magnetocaloric effect compounds Gd5Si2Ge2 and La(Fe13-xSix)Hy; the RCu and RAg families of ductile intermetallics; the mixed intra-lanthanide (R,R')Al2 compounds in which magnetic transitions disappear and reappear as one R is substituted for by R'; and GdNi which exhibits large dilations along two crystallographic directions and a larger contraction in the third direction at the Curie temperature resulting in zero volume change as GdNi orders magnetically via a second order phase transition.COMMERCIALLY IMPORTANT INTERMETALLICSNdFeB Permanent MagnetsThe Nd2Fe14B permanent magnets were discovered in 1984 independently in the USA and Japan. It is a ferromagnet and with proper heat treatment and processing Nd2Fe14B is the strongest near room temperature permanent magnetic material known today. This intermetallic compound is utilized as a permanent magnet in many applications, such as electric motors (e.g. the modern automobile contains up to 35 electric motors), spindles for computer hard disc drives, microphones and speaker magnets for cell phones and other audio equipment, direct drive wind turbines, actuators, and Magnetic Resonance Imaging (MRI) units. There are two kinds of NdFeB permanent magnets – bonded and sintered. The bonded magnets have a lower magnetic strength than the sintered magnet. The highest strength magnets are obtained by small substitutions of Dy (up to a maximum of 10%) for Nd, because Dy can significantly increase the coercivity and thus the energy product (a measure of the magnetic strength or hardness). The bonded magnets account for about 12% of the NdFeB market (~82 metric kt per year, containing ~20 kt/a of Nd). The NdFeB permanent magnet market is growing at a rate of about 15% per year. (Burzo & Kirchmayr, 1989; Kobayashi & Hirosawa, 2001; Coey, 2011)."

Jan 1, 2012

By M. Behrouz

Thermal power plants convert thermal energy due to nuclear reactions or the combustion of coal, gas, heavy oil, or some other hydrocarbon to electrical energy. They consist of a variety of equipment, such as boilers, turbines, generators, cooling towers, and auxiliary equipment. Any factor that affects the equipment efficiency affects the overall efficiency. Analysis of the cooling tower and raw water using the Langlier Saturation and Ryznar Stability Indices showed that the cooling water at Sarchesmeh was slightly scaling with respect to silica. Cold lime softening was found to be a cost-effective method to produce cooling water with adequate properties to reduce the cooling water make up from 85 to 70 m3/h and blow down rate from 35 to 20 m3/h.

Jan 1, 2007

By C Jincheng, L. Liang, L. Wenjun

"Considering overgrinding in a grinding process, the grinding characteristics of comminuted hematite products using a HPGR and a conventional CC were comparatively studied. The major properties including particle size, grinding kinetics and grinding technical efficiency (Et) were investigated. Individual size distributions (ISDs) of -2.0mm in a HPGR product showed a more significant “double-peak” characteristic than a CC product. As a result, HPGR products were finer and had a wider full-size distribution because of the greater proportion of fines. The parameters m and zi in m-th order grinding kinetics were analyzed by the partial-derivative method and the critical time tc(tc = exp (1/ zi)) was obtained. zi mainly affected the breakage rate when t < tc; otherwise, m mainly affected the breakage rate. In these tests, tc was considerably higher than the grinding times, and HPGR products yielded a higher zi-value than the CC product for the same sieve size. This indicated that HPGR products had a higher breakage rate and needed a shorter grinding time for a certain grinding fineness. Et was calculated by simulating the size distributions of batch grinding products. HPGR products gave a lower Et at a decreasing rate than the CC products for -2.0 mm feed and -0.5mm feed, and then showed a slightly higher Et for -2.0+0.5 mm feed. This indicated that overginding in HPGR full-size products was more serious under the condition of coarse grinding, whereas the efficiency was higher and overgrinding weakened significantly in HPGR coarse products because of screening-out fines. Based on the above research, a new process of “ultra-crushing in HPGR – classified grinding” was advanced, reducing ores tonnage into first stage ball mill significantly, improving grinding efficient and weakening overgrinding in the whole grinding process.INTRODUCTIONIn mineral processing, comminution accounts for a substantial portion (approximately 60~70%) of the energy consumed in plants. As an ultra-fine crushing equipment,the application of the HPGR for industrial comminution has been paid close attention because of its low specific energy, low steel consumption, high capacity and high ratio of reduction, among others (Schonert, 1998; Norgate & Weller, 1994; Fuerstenau & Kapur, 1995). HPGRs comprise two counter-rotating rolls that draw feed material into the roll gap. One roll is fixed to the mainframe, while the other movable roll is mounted on slides and positioned by hydraulic rams. The specific pressing force (SPF) (i.e., total force divided by projected roller area) is typically in the range of 3~9 N/mm2 depending on the application, while pressures of up to 1000 N/mm2 have been measured within the operating gap (Maxton , Morley, & Bearman , 2003)."

Jan 1, 2016

By G. G. Richards, D. J. Rioux, R. L. Stephens

Teck Cominco Metals Ltd. operates an integrated zinc-lead complex at Trail, British Columbia, Canada. The year 2007 marks ten years of operation of KIVCETTM flash smelting technology for the treatment of zinc plant residues and lead concentrates. Since start-up in 1997, the furnace throughput has been increased to exceed its design rate and other metallurgical performance targets while continuing to meet its environmental objectives. This was achieved through resolution of key mechanical issues, improved understanding to stabilize the reaction shaft operation and control furnace accretions, significantly reduced boiler corrosion by molten chloride salts through the extensive application of weld overlay, a suite of projects to improve furnace integrity, and some debottlenecking of the surrounding unit operations in the lead smelter. The combination of increased feed rate and improved on-line time allowed the KIVCETTM furnace to set a new quarterly feed throughput record of 129,300 tonnes in the first quarter of 2008.

Jan 1, 2008

By Mory Ghomshei

As fossil fuels become depleted over the next century, it is imperative that Canada and other countries examine ways to transition to other sources of energy, particularly renewable resources. A critical obstacle to developing Canada?s renewable energy resources is the scarcity of infrastructure to wheel the generated electricity to a viable market. For each megawatt of renewable electrical power, a maximum of 1 km of connecting power line is typically feasible. This means that hydropower, geothermal, and wind power projects with capacities up to 100 MW must be located within a maximum of 100 km of a main power line in order to be economically viable. With a total length of about 1200 km, the proposed Northern Gateway oil pipeline project creates an excellent opportunity to become a corridor that can seed renewable energy projects in Northern British Columbia and Alberta. Utility companies must build new infrastructure to provide the electricity for constructing and operating the proposed pipeline. The pipeline and linked power line infrastructure therefore, should be designed and built with consideration to create an energy highway to the significant renewable energy resources, such as hydro, wind, and geothermal, in the vicinity of the proposed pipeline. Some of the important renewable energy resources in northern British Columbia can be developed in connection with the proposed pipeline. It is estimated that close to 2,500 MW of commercially viable wind, geothermal and run-of-river power resources are present in the proximity of the proposed pipeline corridor. While oil flows westward from the Alberta bitumen fields, the generated green power can flow eastward to help the Canadian oil sand industry to offset as much as 10 Megatons of carbon emissions per year. The generated carbon credits are equivalent to 75% of the emissions associated with extraction of the 525,000 barrels per day of oil from oil sands, intended to be carried by the pipeline.

Aug 1, 2013

By J. M. Ortiz, J. P. Bertini

"In mineral resource and ore reserve estimation, several sources of information are generally available, such as diamond drillholes, reversed-circulation drillholes, and blastholes, and originate from one or more sampling campaigns and are analyzed by one or more laboratories. In such a situation, the grade measurements may not have the same precision and one should distinguish between hard and imprecise data.This work aims at studying the impact of data imprecision in resource/reserve evaluation through two case studies on simulated deposits: a porphyry copper deposit conditioned to real exploration and production data, and a gold deposit simulated without any conditioning data. Several geostatistical techniques are used to estimate the grades of selective mining units from exploration samples, including kriging, cokriging, lognormal and indicator kriging. Two types of imprecision are examined— measurements with multiplicative errors and measurements defined as intervals. The results are compared to the simulated grades of the selective mining units from a statistical and economic viewpoint.The study concludes that imprecise measurements should never be discarded because they help to improve the estimates, and that simple methods such as kriging are as efficient as more sophisticated ones for resource/reserve assessment. Finally, a few indications on how to diagnose and model the data imprecision are given."

Jan 1, 2005

By K. Prajapati, P. Hes

Transmission of vibration to the operator from percussive vibrating tools is increasingly of concern in industrial and mining applications. Prolonged exposure to high levels of vibration transmitted via the hand causes disorders known as hand-arm vibration syndrome (HAVS). The vascular component of HAVS is called vibration white finger (VWF) and has a debilitating effect on the hand. Vibration at frequencies below 1250 Hz, a tight hand-grip force and cold environments are reported to increase the likelihood of developing VWF. A vibration damping handle design with patents pending that addresses some of the causes of VWF has been developed and retrofits onto jackleg pneumatic rock drills. The handle is decoupled from the drill while maintaining jackleg twist-grip controls on the hand-grip using a combination of sealed self adjusting hydraulic pistons and compliant materials in series, and a new air control valve. The ergonomics of the hand-grip was also modified by the addition of a polyurethane sleeve with a diameter of 50 mm. The new hand-grip reduces direct cold metal contact and minimizes grip force. Measurement of vibration as the quantity acceleration was made in accordance with international standard ISO 5349. Overall vibration damping in all axes of 50% to 63% was attained at frequencies below 1250 Hz. The dimensions of the damping handle are comparable and its weight is only 100 g heavier than a standard handle.

Jan 1, 2001

By P. Ramirez

"To achieve an optimal metallurgical performance in the flotation process the bubble diameter should be between 0.5 and 2.5 mm. To control bubble size, frothers are added, reducing bubble size and conferring bubble stability against coalescence. However, the bubble generation mechanism determines predominantly the bubble size distribution produced. In mechanical flotation cells, bubbles are produced by the shear stress generated by a rotating blade on a gas stream. This mechanism produces a log normal bubble size distribution. In contrast, in column flotation, jetting gas injectors are commonly used in Chile and the bubble size distribution is bimodal with small and large bubbles. Bubbles larger than 2.5 mm mean a loss in surface area, while bubbles smaller than 0.5 mm move with the pulp stream and therefore collide less frequently with particles. In this paper, a new device based on a jetting sparger and a deflector disc (impinging jetting) is evaluated as an alternative sparger for column flotation.The new device was tested in a rectangular acrylic cell 1 m × 0.5 m × 3 m. High-speed cinematography was used to compare bubble generation with jetting and impinging jetting at different gas velocity in the nozzle (5–50 m/s). From the image analysis, it was observed that the deflector induces a shear stress, in analogy to a rotating blade but in this case the shear results from a high velocity gas hitting a static surface. The device was evaluated in a 0.5 m diameter 3 m high column. The McGill bubble viewer technique was used to compare the bubble size generated by jetting and impinging jetting. It was found that the Sauter mean bubble diameter reduced from 7.4 mm to 2.8 mm, when the jetting sparger was modified with the deflector. In the case of the impinging jetting sparger, 70% of the bubbles were in the effective range for flotation, while for the jetting sparger, only 10% were in the effective range."

Jan 1, 2016