The National Metallurgical Laboratory in the development of Mineral Beneficiation and Extractive Metallurgical Techniques

In the context of India's mineral resources, the author discusses researches on mineral beneficiation and deve-lopments in extractive metallurgical techniques, and outlines the role of the National Metallurgical Labo-ratory in this respect. General particulars are furnished of the work done on beneficiation of manganese, chromite, graphite, pyrites, etc., and of the extractive metall-urgical themes under development at the Laboratory, in-cluding pilot plant investigations on electrolytic mang-anese and manganese dioxide. A review of the Laboratory's programme of work during the second Plan, which includes the setting up of pilot plant projects on thermal bene-ficiation of low-grade manganese and chromite ores and the treatment of low-grade manganese, chrome and other ores by ore-dressing methods, is also given

Recent Trends in Iron and Steel Technology

During the last decade, world annual ingot steel produ-ction has increased by about 150 million tons as shown in Fig. 1. Nine-tenths of the total pig iron produced forms an intermediate product for conversion into steel. Such post-war expansion has been actuated by the rapid growth of light and heavy engineering industries, increased demands of consumer goods and the universal desire to obtain higher standards of living. One twentieth of the earth's crust consists of iron which should assure the supplies of this important metal as inexhaustible. This could be so if the production and processing techniques are under continuous transformation in relation to the nature of available resources

Some aspects of Pilot Plant Research and Development in Iron and Steel Industry

Students of ferrous metallurgy appear unanimous in their opinion that major revolutions are taking place in the technology of iron and steel production whilst the essence of basic reactions and fundamentals invol- ved remains unchanged. Apart from the physical enlar- gement of smelting units proper and scaling up of anci-llary equipment, some of the major advances currently under application relate to raw-materials processing & prepared burdens such as, sizing, classification,conce-ntrating, agglomeration, sintering etc. which have to-day become bywords to increased productivity and reduced operational costs. Similarly important techni- cal developments are taking place in iron blast furnace operations, stool-making technology, continuous casting technique and in related fields. Those industrial devel-opments are the products. of laboratory scale researches followed by comprehensive investigations on pilot plant scale trials. The importance of such pilot plant trials has been recognised the world over . In this short paper, some of these pilot plant scale investigations will be highlighted including some current technical develop- ments in the technology of iron and steel production in different steel producing countries of the world

Micro-Metallurgy of Alloy Steels

Whilst extensive literature exists on the effects on the properties of steels of alloying elements present in relatively large amounts , data are scanty and disp-ersed on the role of minute additions which exercise relatively far larger physical and metallurgical effects. The elements involved may be added in traces or present in residual amounts. It has been endeavoured to highlight the highly beneficial effects of minute additions in many respects, such as those of rare earths to cast plain carbon and boron- treated steels, to wrought steels, to highalloy stainless steels , etc. The subject is of recent development , but is of great importance in view of the immense resources in India of the rare earths group of minerals

Effects of Austenitic Grain Size & Other Factors on the Brittle Failure of Mild Steel

The manifestation of rittle fracture in mild steel fabricated structures has been known for sometime but came into the lime-light following the failure during the last war, of all-welded American-built ships very often into two halves. In this short paper the importance of the subject has been stressed in relation to Indian conditions. Various factors which contribute to brittle fracture of mild steel have been reviewed and those which reduce the propensity towards brittle failure, like the austenitic grain size of steel and manganese carbon ratio, have been discussed at some length. The effects of stress raisers and constraint provided by the surrounding metal in developing triaxial, volumetric tensional stresses leading to brittle failure of mild steel have been out-lined

Indian Manganese Ores and their Thermal Beneficiation for Ferromanganese

A review is made of Indian manganese-ore resources and their characteristics discussed in the context of the question of their utilisation for ferromanganese manu-facture with selected fuel, low in phosphorus, in an iron blast furnace or in a Soderberg electric furnace. The projected plans for ferromanganese production in the background of the steel expansions envisaged in the second Plan are outlined. Attempts made abroad in respect of pyro-metallurgical processes for thermal beneficiation of low-grade manganese ores' are also discussed—and ini-tial work done at National Metallurgical Laboratory in this field is noted and details of a pilot-plant scheme drawn up for thermal beneficiation of low-grade ores, including the design of the rotary furnace to be employed, we furnished. Mention is also made of the project on low-shaft-furnace smelting of iron ores with non-coking coals being set up at Jamshedpur through the joint efforts of National Metallurgical Laboratory and the Tale Iron and Steel Co. Ltd. Possibities of comIncting experimental synching on Demag-Humboldt principle are also referred to

Tailor-Made Alloy Constructional Steels

In this paper, a general account is presented of methods of substituting brains for excess steel in constructional applications in which steels are consumed in large tonn-ages. Attention is particularly drawn to the hardenability approach. The specific effects of common alloying elements in steels individually and in combination are outlined. The enhancement of hardenability by small amounts of boron is touched upon and it is emphasized that a little of two or three elements employed in conjunction in ' triple steels ' has often a more potent beneficial effect than the same total alloy content in steel of any one of the three alloying elements. The structural factors in harden-ability which are often ignored, are discussed and conside-ration given to the question of finding the best techni-ques for securing uniform hardenability in the product of an ingot. The subject-matter has been discussed against the background of indigenous alloying elements and the most effective uses to which they could be put for present and future Indian requirements

Indian Manganese Ore Industry & Scope for its Development

In this short paper are reviewed the reserves of Indian manganese ores and their quality. Emphasis has been laid on different possibilities of their exploitation for the manufacture of ferro-alloys in this country and export of the latter in preference to that of raw unprocessed manganese ores. Mineral upgrading by ore-dressing methods of low-grade manganese ores has been referred to, followed by the possibilities of their thermal beneficiation for the production of ferro-manganese. In this connection the efforts of countries deficient in manganese mineral to tap all possible sources of manganese,such as recovery from steel slags, manganiferous iron ores, etc., have been discussed

Service Failures of Engineering Metal Components

Machines of conventional design often suffer serious service failures. Various contributory factors thereto have been examined in this short paper such as unsuitable choice of materials,faulty melting and processing history, faulty heat-treatment, poor machining and surface finish, careless handling and last but not the least the damaging effects of stress-raisers , notches etc., in relation to fatigue failure of metals. The paper is illustrated with brief accounts of some typical service failures investigated in the two year's old National Metallurgical Laborator

Temper-brittleness: Part I - Unalloyed Steels

It was until recently accepted that unalloyed steels were not susceptible to temper-brittleness and that alloying elements introduced temper brittleness. A directly oppo-site view has been set forth in this paper , namely that unalloyed steels are not only susceptible to temper-brittleness but also temper-embrittle much more rapidly th.rn alloyed steels based on the observations of brittle transition temperature ranges. Temperbrittleness and strain-age-emhrittlement are discussed in relation to minor or residual chemical constituents like nitrogen, oxygen , etc. The role of stabilizing elements like alum-inium , titanium, vanadium and of nitrogen in minimizing and often wholly suppressing temper - brittleness and strain- ageing is discussed at some length. The subject of blue-brittleness has also been touched upon. The observed phenomena are considered in terms of dislocations and certain gaps in the theory are pointed out