Mathematical modelling: A wonderful tool if Judiciously used

The excerpts of the lecture delivered by Prof. S.P. Mehrotra on the occassion of CSIR Diamond Jubilee Celebration

Computer Aided Design and Synthesis of Flotation Circuits

The design and synthesis of flotation circuits is conven-tionally based on rules of thumb derived from industrial practice. The heuristic approach is dependent on past experience and engineering judgement of experts. With the advent of relatively inexpensive computing power and easy availability of powerful optimization techniques, it is now possible to synthesize optimal multicomponent, multi-stage flotation separation base on rigorous quantitative analysis of alternate possibilities. For optimum synthesis of flotation circuits both cir-cuit. configuration as well as operating parameters are optimized simultaneously. Existing literature on circuit synthesis and optimization is broadly divided into two groups. While the literature pertaining to group one incor-porates the flotation models directly in the optimization models, those belonging to the second group use flotation models to characterize the constraints on component flows from a flotation bank only. The mass balance equation comprising the optimization models in the latter cate-gory are independent of flotation models. Recent advances in the field are reviewed in this paper

Mathematical Modelling of Contrinuous Casting of Steel Strips by Single Roll Process

Schematic representation of the Single Roll Continuous Casting of Steel Strips is shown in Figure 1. The liquid metal at a particular temperature Tl it held in the res-ervoir where the liquid metal level is always kept cons-tant. The metal continuously enters the annular space between the rotating chilled drut and the nozzle block through a graphite (refractory) nozzle. As soon as the molten metal comes in contact with the drum a skin of solid metal is formed which continues to grow as long as the liquid is in contact with this solidifies skin. Water at an input temperature TC extracts heat from the copper drum between the angles h and P2 . The drum rotates at an angular velocity W is anticlockwise directio

Iron Ore Resources and Beneficiation Practices

Iron and Steel Industry provides foundation for indust-rial development of a country. The per capita consumption of steel is considered as one of the important parameters of a nation's prosperity. Iron ore is the basic raw mater-ial for iron and steel making. The world reserves of iron ore are estimated to around 370 bill on tonnes. The prin-cipal minerals of iron are the oxides(hematite and magne-tite), hydroxide (limonite and goethite) and carbonate (siderite). In nature the commercial deposits are mostly of bed type, although deposits of magnetic, contact meta-somatic and of a replacement nature also exist. In many cases, ground water circulation and weathering have resul-ted in concentration of the ore from primary sources. The major iron ore producing countries in the world are the Australia, Brazil, Canada, China, India, USA, Russia, Kazakhstan, South Africa, Ukraine and Sweden. Pre Cambrian banded iron formations containing 30% or more of iron are the predominant sources of iron

Studies on Particle Suspension in Air-agitated Pachuca tanks

The paper presents the findings of an investigation involving extensive experiments on three laboratory scale Pachuca tanks to examine the effect of design and oper-ating parameters, as well as scale up on particle suspension. Some important results, crucial to the design and scale up have emerged. Full center column (FCC) Pachucas with a draft tube to tank diameter ratio (Dd/Dt) on the order of 0.1 are found to be energetically more efficient in suspending particles than Free-Air.Lift (FAL) and Stub Column (SC) Pachuca tanks. It has been established that the energy required for generating suspension from settled particles is more than that is required for maintaining the particles already in suspension. The magn-itude of hysterisis in FCC Pachuca tanks is of the order of 20%. Effect of novel split air injection technique on critical velocity for particle suspension has been rigorously investigated. Split air injection, with 30% air injected into the annulus from top and 70% air injected from the bottom into the draft tube lowers the critical air velocity for particle suspension by about 37% with respect to bottom blown Pachuca tanks. Mechanisms for particle suspension in bottom blow Pachucas as well as those with split air injection are proposed

Frontiers in Mechanochemistry and Mechanical Alloying

The book Frontiers in Mechanochemistry and Mechanical Alloying [ISBN : 97881-87053-69-8] (Rakesh Kumar, Srinivasan Srikanth and Surya Pratap Mehrotra (Eds.))is a compilation of papers presented in the VI International Conference on Mechanochemistry and Mechanical Alloying (INCOME) held at CSIR-National Metallurgical Laboratory (CSIR-NML), Jamshedpur (India) during December 1-4,2008 under the aegis of International Mechanochemistry Association (IMA). Fifty three papers (334 pp) included in this book are written by experts from all over the world

Mathematical Modeling of Particle Stratification in Jigs

Recognizing mathematical modeling as a powerful tool for systematic process analysis and control, this paper attempts to critically'review the theories and mathem-atical models which have been advanced to explain and simulate the behaviour ofjigg ing process. The existing literature on mathematical modeling and quantitative analysis of jigging has been divided into six subheads : (i) classical theory, (ii) potential theory, (iii) dispersion models, (iv) energy dissipation theory, (v) stochastic analysis and (vi) empirical models. A new modeling approach based on Newtonian mechanics is used to describe the stratification behavior of particles in jig. In this approach,the motion of solid material is treated using the discrete element method (DEM) while the corre-sponding motion of the liquid is determined by marker and cell (MAC) technique. For illustration purpose, a jig bed consisting of 100 particles of two different densities is simulated. Preliminary results show that the model predicts the stratification of particles reasonably well

Effect of electroplating industrial waste on “available phosphorus” of soil in relation to other physicochemical properties

Unorganized land disposal of industrial wastes contaminates land and ground water. The Wazirpur Industrial area of Delhi, a metropolitan city, generates highly acidic (pH 2 - 3.8) and toxic waste, and disposal remains a perpetual problem. This waste contains a high quantity of macronutrients as well as heavy metals because major industries are involved in metals finishing. Wastes of these industries were mixed with municipal waste at roads. Hence a study was undertaken to verify the suitability of land disposal of this toxic waste. The waste was first treated with three doses of lime (0, 0.5 and 1%) and then mixed with two types of soils from two different locations in three different proportions viz. 10, 20 and 30%, maintaining soil moisture level at 50% of water holding capacity. These samples were incubated for 120 days. All three waste amendments resulted in an increase in available phosphorus (AP) in both waste- amended soils as compared to the control soils. It is statistically significant at p = 0.05 level. During the 120 days of incubation highest value (36.41 ± 0.01 ppm for site 1 soil and 30.40 ± 0.03 ppm for site 2 soil) of available phosphorus had been found at 20th day of incubation for both the soils. Lime treatment at the rate of 0.5% gave in 10 and 20% treatments significantly positive result as compared to 0 and 1% treatment. Only in 30% waste amendment 1% lime treatment gave better amount of available phosphorus (27.77 ± 0.01 ppm and 24.84 ± 0.03 ppm for site 1 and site 2 soils respectively). The finding of the study evident that 0.5% lime treated 10% industrial waste can be used as manure for soil. The result is of further interest from a plant nutrition standpoint since the amount of potentially mobile-P measured in this study could be related to the amount of available phosphorous required for crop growth.Key words: Industrial waste, land disposal, incubation study, available phosphorus

Thin Layer Chromatography of Pesticides and Their Residues

Recent progress in the analysis of organo-phosphorus, organo-chlorine, carbamate, urea, uracil pesticides and their residues by thin layer chromatorgraphic methods employing chemical and enzymatic methods is reviewed

Mechanical activation of solids in processing of minerals and wastes

Recently, there has been an increasing interest in mechanical/mechanochemical activation of solids for developing new materials and metallurgical processes. In this paper, a brief overview of our research in this area is presented. Select applications of mechanical activation are discussed with emphasis on characterisation of activated materials, and the prospects and possibilities of developing improved/novel processes. The main applications covered include the Bayer process of alumina production, and blended cement manufacturing