Thermodynamic aspects of chemical Reactions, as applied to the smelting & Refining of lead

With a reference to the formulae employed in chemical thermodynamics , available data on thermodynamics of chemical reactions involved in the extraction and refining of lead are brought together. Equilibrium constants of the reactions have been calculated from the standard free energy data to explain the desideratum of optimum working conditions required during roasting, smelting and refining of lead . Graphs showing the changes with temperature of standard free energies of formation of oxides, sulphides, chlorides , fluorides , sulphates,carbonates and silicates have been incorporated for ready reference

Temper-Brittleness: Part II- Alloy Steels

In the case of alloy steels the modus operandi of minor elements and of phases such as nitrides.carbides, etc., in causing temper-brittleness has been experimented upon, discussed and speculated over probably more than any other alloy steels subject.The most interesting problem in this field is the suppression of temper-brittleness in nickel-chromium steels by means of molybdenum. The underlying phenomena still remain largely unresolved and no clear picture has been developed by what other elements act in the same way as molybdenum.From the discussion it emerges that temper-brittleness must be considered in terms of brittle transition temper-atures. The effects of aluminium and molybdenum, in lowering the ductile to brittle frac-ture range in alloy steels, have been outlined.It has been shown that the susceptibility ratio depends on grain size and an etchant based on solution of picric acid in ether can furnish metallograpliic evidence of temper-rittleness. Hypotheses put forward to explain temper-brittleness are stated and suggestions made for further research

Substitution of Alloying Elements by Grain Size Control of Alloy Steels

Fine-grained steels have many advantages such as are usually obtained through additions of alloying elements; among these are: wider heating ranges and higher grain-coarsening temperatures, relative freedom from low tempe-rature embrittlement, higher toughness at a given strength, less trouble from warping and distortion, greater uniformity in response to heat treatment, and simplification of heat-treating cycles by elimination of treatments such as post-carburizing, refining, etc. It has been brought out in this paper that for many appli-cations grain-refined carbon steels can replace coarse-grained low-alloy steels, excluding, of course, cases where hardenability is critical. The uses of grain-refined steels in automotive applications have been outlined. Grain size control of low-alloy heat-treated steels is part of normal specifications in the U.S.A., but general acceptance of such specifications has been lacking in the U.K. and Europe. In India the U.S.A. grain-size specifi-cation pattern is followed slavishly by some firms, but the other firms follow the U.K. practice. A plea is put forward to rationalize this practice and evolve a uniform attitude to grain size control inthe industry

Iron production in low-shaft furnace plants with Indian raw materials

CONVENTIONAL iron production in a blast-furnace is based on lumpy or agglomerated burden or their optimum comb- ination employing strong and abrasion-resistant metallur- gical-coke. Smelting of iron in a low-shaft furnace can, however, be undertaken with non-metallurgical coke and lignite coke. The use of one component self-fluxing briquetted burden or lumpy charge of sized iron ore fines and fuel, has been investigated in the Low-Shaft Furnace Pilot Plant of the National Metallurgical Laboratory. India has more or less uniformly dispersed deposits of good iron ore in the country. Coal reserves of India on a conservative estimate are 'figured at 20 000 million tonnes of which only 1 500 million tonnes are coking coal suitable for conversion into strong metallurgical coal. Deposits of metallurgical coal lie over a small geogra-phical area on the Bengal-Bihar border in India. As such, iron smelting plants in different parts of India utilizing regional iron ores and non-metallurgical fuels present attractive possibilities thereby eliminating expensive and over-congested rail transport of foundry grades of pig iron which is subsidized by the State to maintain uniform selling prices thereof in all parts of the country

Scenarios of Waste and Resource Management: for Cities in India and Elsewhere

Rising prosperity around the globe – welcome and overdue in many respects – has certain undesirable consequences. It leads to an increase in the demand for raw materials, putting pressure on our limited natural resources. At the same time, due to dominant linear economic models of make-use-throw, increasing prosperity also leads to generation of waste. Rising quantities of waste are a global challenge. The challenge manifests itself most visibly in large cities around the world but is more acutely felt in developing countries. Dealing effectively with rapidly increasing amounts of waste is a complex management challenge. Environmental, business, political and social considerations play a role. This report suggests a framework for working through these complexities by focusing on two critical and interconnected questions. First, is waste conceived of as a burden to be got rid of or a resource for generating income and employment? Second, is the waste/resource managed by actively engaging the urban informal sector or tolerating the informal sector merely on the margin? The latter is a burning issue for cities with many poor people. The report identifies four future scenarios of this complex waste/resource management landscape using tools from Foresight methods and political economy analysis. We also identify the dynamics within and across the four scenarios. Although the four scenarios developed in the report represent stylised constructs, they were developed in a participatory workshop and represent stakeholders’ views about their current problems and future ambitions. At the same time, they represent political choices that would influence the development of a particular approach of waste/resource management in a city. Our results have implications for enhancing understanding of the policy choices that can be made today to influence waste/resource management in the future. The methods and results also offer insights into future research on waste/resource management.UK Department for International Developmen

Low Shaft Furnace Smelting of Pig Iron in India

AS IRON and steel enter in all other industries in some form or other, the industrialisation of a country depends on the production of iron and steel. Production of pig iron, which is ultimately converted into steel, depends on the availability of raw materials like iron-ore, and coking coal of suitable grades. The conventio- nal method depends on the reduction of lumpy iron-ore or sintered iron-ore with abrasion resistant coke in prese-nce of limestone in a blast furnace. The increase is the height of the furnace to increase the capacity and ther- mal efficiency necessitates the use of good strong coke which call only be obtained by carbonisation of coking coal. As the modern blast furnace consumes 1,500-2,000 lb of coke per ton. of pig iron, considerable attention is paid to minimise the coke-rate and thereby reduce the cost of iron production.For this purpose the temperature of the blast furnace gas should be as low as possible to reduce the sensible heat carried away by the gas and the, ratio of CO : CO2 in the top gas should be as near as possible to the equilibrium value. Both these factors have contributed towards the increase in the height of the furnace. Requisite raw materials for blast smelting are becoming scarce, as in some countries coking coals are not available and the ores are soft and obtained as fines

A Comparative Study of Non-Ferrous Coatings on Steel

Considerable tonnages of zinc and tin are imported annually to meet the demands of galvanizing and tinning industries. Keeping in view the availability of raw materials in India, the possibilities of using aluminized steel are discussed. A comparison of the micro-structures obtained in different hot-dip processes for protection of steel surfaces and of the resistance of the coated products to corrosion is given. Points in favour of aluminium-coated steel have been brought out

Hot Dip Aluminising of Steel Wire- Laboratory Scale Investigations and Pilot Plant Studies

Protective quality of aluminium due to its adherent surface oxide film is well known. In hot-dip aluminising the use is made of this protective nature of aluminium by coating the steel base by dipping it in molten aluminium bath there-by getting an outer aluminium layer & an iron-aluminium layer at the interface. The interfacial alloy layer though possessing good atmospheric corrosion and resistance to oxidation at high temperature is brittle in nature and such must be kept to a minimum of thickness where the end use of aluminised product is for deep drawing, forming etc. Hot-dip aluminium coating on steel base comprising the outer aluminium layer and an alloy layer in the interface should possess both atmospheric & high temperature corrosion resistance

L-D Oxygen Converter (1)

EVER since steel has become the primary index of a nation's basic industrial prospect, tireless efforts are being made by the metallurgists all over the world in recent Years to produce more and more steel by comparatively easier and cheaper methods. Whereas fundamental research workers are advancing slowly and steadily to study critically the Various thermodynam- ical reactions involved in the refining of pig iron to steel, the process metallurgists are advancing at a very rapid speed to alter and increase the kinetics of steelmaking reactions and hence to increase the throughput per unit time

Preparation of Aluminium-Silicon Alloys by Aluminothermic Reduction

Alloys of aluminium-silicon have today attained considerable commercial importance in their wide use for multifarious applications and as much as 80 per cent of the world's production of light alloy castings have been estimated to belong to the family of these alloys. Based on thermodynamical data , the reduction of silica by aluminium is feasible . It was observed that substantial reduction of quartz depends upon a number of factors, the chief of which are; particle size of quartz, amount of cryolite in the charge, temperature of the reactants and holding time.Physical properties of the alloys made by this method have been compared with the physical properties of corresponding alloys produced by direct alloying of the two metals. This comparison yielded identical results in the two cases. It has finally been stressed that this method can be usefully exploited for commercial applications in countries dependent on silicon imports and rich in bauxite and quartz such as India