Integrated Steel Plant Research Articles

A STUDY OF MANAGING LIQUIDITY

Since privatisation, to ensure swift economic development it was deemed essential that a sound steel production program on a formidable basis must be formulated. Accordingly, the private sector has set up many more integrated steel plants and enhanced the existing plants to increase current production capacity. To some extent the priority given by the country failed to flourish due to poor capacity, under-utilisation and poor consumption. Working capital is accountable for poor capacity, under-utilisation and poor consumption. The competence of the working capital in terms of short-term liquidity is of foremost significance in the case where we examine performs and guiding principle presently overcoming in an industry with a view to finding out whether they are reasonable or require enhancement. The effectiveness of working capital is of crucial importance if short-term liquidity position as well as short-term solvency position is very acceptable and at the same time, if judgement is made with its standard or benchmark. The overall efficiency is vital from the viewpoint of short-term liquidity and at the same time proper plane of profitability is required for the business enterprises. Consequently, the affiliation between short-term liquidity and profitability is one of the most imperative areas necessitating management analysis. Keeping this in view, a study of liquidity management of the selected private sector steel companies is undertaken in the present work.

Prioritization of maintenance tasks on industrial equipment for reliability

PurposeThis paper aims to prioritize preventive maintenance actions on process equipment by evaluating the risk associated with failure modes using predictive maintenance data instead of maintenance history alone.Design/methodology/approachIn process plants, maintenance task identification is based on the failure mode and effect analysis (FMEA). To eliminate or mitigate risk caused by failure modes, maintenance tasks need to be prioritized. Risk priority number (RPN) can be used to rank the risk. RPN is estimated invariably using maintenance history. However, maintenance history has deficiencies, like limited data, inconsistency etc. To overcome these deficiencies, the proposed approach uses the predictive maintenance data clubbed with expert domain knowledge. Unlike the traditional single step approach, RPN is estimated in two steps, i.e. Step 1 estimates the “Possibility of failure mode detection” and Step 2 estimates RPN using output of step 1. Fuzzy sets and approximate reasoning are used to handle the uncertainty/imprecision in data and subjectivity/vagueness of expert domain knowledge. Fuzzy inference system is developed using MATLAB® 6.5.FindingsThe proposed approach is applied to a large gearbox in an integrated steel plant. The gearbox is covered under a predictive maintenance program. RPN for each of the failure modes is estimated with the proposed approach and compared with the maintenance task schedule. The illustrative case study results show that the proposed approach helps in detection of failure modes more scientifically and prevents “Over maintenance” to ensure reliability.Originality/valueThis approach gives an opportunity to integrate the predictive maintenance data and subjective/qualitative domain expertise to evaluate the possibility of failure mode detection (POD) quantitatively, which is otherwise purely estimated using subjective judgments. The approach is generic and can be applied to a variety of process equipment to ensure reliability through prioritized maintenance scheduling.

Failure Analysis of Radiant Tube Burners in Continuous Annealing Line (CAL) of an Integrated Steel Plant

Failure analysis of radiant tube burners (ACI HK 40 with composition ~25 wt.% Cr, ~20 wt.% Ni) removed from a continuous annealing line (CAL) of a cold rolling mill (CRM) of an integrated steel plant was performed using optical microscopy (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and microhardness measurements. Studies revealed that the failures were mainly attributed to combined influences of creep and carburization-assisted localized oxidative attack. A suitable heat-resisting cast austenitic stainless steel was identified as a candidate alloy to replace the previously used ACI HK 40 alloy.

Steelmaking plants: towards lower energy consumption and lower CO2production using more electricity

Production processes of integrated steel plants, mostly based on coal as an energy source, produce about 2 tons of CO2 per ton of steel. As specific CO2 production has to be decreased by 20% in the mid-term (2020), immediate action is required to further decrease the specific energy consumption. The integrated plant is not energy self-sufficient as extra electricity must be bought from outside, but on the other hand, produces an excess of process gas that has to be used within the plant. Optimisation of the use of the internally produced gases is a key issue as either they are burned at the power plant with a conversion yield to electricity of about 40% and often much lower, or might be valued in the plant internal heat exchangers with a much higher efficiency such as ~90% in the hot stoves or ~65% or more in the present reheating furnaces. This paper shows that using the high-value coke oven gas as a chemical reactant (for DRI production) leads to significant extra metal production. From a global viewpoint, this extra metal production is almost carbon-free, as it requires only electricity for its manufacture.

Study of spatiotemporal variation of atmospheric mercury and its human exposure around an integrated steel plant, India

Abstract. Mercury release by coal combustion has been significantly increased in India. Mercury content in coal has been analyzed to 0.272 ppm by Central Pollution Control Board. Toxicological effects of elemental Hg (Hg0) exposure include respiratory and renal failures, cardiac arrest, and cerebral oedema, while subclinical exposure may induce kidney, behavioral, and cognitive dysfunctions. The present work is focused on dispersion pattern and inter-phase exchange phenomena of ambient mercury between air-particulate matter evaluations of alongwith dominance of various major routes of human exposure-dose response using regression analysis around an integrated steel plant in central India. Source-downwind type stratified random sampling plan using longitudinal study design has been adopted for ambient monitoring of total mercury, while representative sampling plant has been adopted for persona exposure-dose response study In space-time framework. Control sites and subjects have been chosen from uncontaminated area (100 km away from any industrial activities). 06 ambient air monitoring stations and 17 subjects from workers, non-workers but local residents' categories and from controlled sites have been chosen for the study. Samples of mercury biomarkers (blood, breast milk and urine) have also been collected from same subjects in each month during sampling period. The sampling period was March 2005 to February 2006 . Samples of 30% acidified KMnO4 for air-Hg absorption, PM10, RPM and biological samples were analyzed for total mercury by ICP-AES using standard methods. Local soils and ground water were also monitored for total mercury content during the sampling period. Results have shown that mercury concentration is very high compared to prescribed limits in all receptors. Results of exchange phenomenon have shown the higher transfer of mercury from air to particulate during combustion in steel plant environment due to presence of huge amount of iron particles, in contrast to results obtained in other industrial locations earlier. Plant workers have shown 1.5 to 2.5 times higher personal RPM-Hg levels compared to Category 2 and 20–30 times higher than Category 3. All biomarkers have shown higher Hg presence compared to prescribed standards. Regression analysis between exposure routes and bio-receptors has been investigated. Dominance status of selected routes of bio-accumulation has been varied from category to category.

Energy Balance Analysis and Energy Saving Opportunities for Erdemir Slab Furnace #3

Eregli Iron and Steel Works Co. (Erdemir) is the largest integrated steel plant in Turkey. In this study, the potential for improving the specific energy use of slab furnace #3 of this plant was analyzed. An energy input and output model was established in order to determine the lost energy in the process. According to the study, energy efficiency of slab furnace #3 was calculated as 64.26%. Even though it seems to be a reasonable efficiency value for a slab furnace, it was noticed that further energy conservation can still be achieved by increasing the temperature of hot charging to the slab furnace and recovering the flue gas sensible heat remaining after the recuperator.

Specific Energy Consumption Analysis of Turkish Integrated Steel Plants and Sustainable Energy Management in Erdemir

Specific energy consumption analysis of the integrated steel plants in Turkey was performed in this study by using the data of 2003–2005. Specific energy consumptions of three integrated steel plants were determined as follows: 30.3 GJ/TCS for Karabuk Iron & Steel Works Co.; 29.8 GJ/TCS for Iskenderun Iron & Steel Works Co.; and 21.5 GJ/TCS for Eregli Iron & Steel Works Co. The results of the specific energy consumption analysis indicated that Eregli Iron & Steel Works Co. (Erdemir) has the lowest specific energy consumption for steelmaking process in Turkey. The energy structure and management processes providing sustainability in Erdemir integrated steel plant was presented in detail.

Innovation, imitation and dependence: iron and steel technology in India, 1970-1990

The paper examines the adoption of the innovations of the 'centre' by the Indian integrated steel industry (in the 'periphery') and lack of autonomous technological development, despite the potential, during 1970-1990. Imported technology was not subjected to any significant local adaptation and modification; further, there were hardly any autonomous technological innovations. Local ferrous metallurgical R&D, steel plant design and engineering, and the associated capital goods industry were weak and undeveloped, with tenuous linkages among themselves, and with the integrated steel plants.

Conceptual design and simulation analysis of thermal behaviors of TGR blast furnace and oxygen blast furnace

Extensive use of carbon based fuel is the main inducement for global warming and more extreme weather. Reducing carbon dioxide emission and enhancing energy use is a common subject in steel industry. In the integrated steel plant, decreasing carbon dioxide emission must consider energy balance in the whole iron and steel works, and secondary energy must be actively utilized. As promising blast-furnaces, top gas recovery blast furnace (TGR-BF) and oxygen blast furnace have been investigated. In this paper, conceptual TGR blast furnace and oxygen blast furnace are proposed. Base on the idea of blast furnace gas de-CO2 circulating as reducing agent and the idea of pure oxygen blast decreasing the thermal reserve zone temperature, process modeling is conducted with ASPEN Plus. It is shown that the developed model reasonably describes the energy balance and mass balance feature of the furnace, and provides basic thermodynamic condition for furnaces. The effects of changes in different operation conditions are studied by sensitivity analysis and reference data from simulation.

On the integrated charge planning with flexible jobs in primary steelmaking processes

The integrated charge planning (ICP) problem based on flexible jobs in an integrated steel plant is extremely difficult and valuable. The purpose of this paper is to improve the efficiency and feasibility of planning by minimising the number of charges, minimising the total production costs and maximising the total throughput, considering the hard constraints and soft constraints. A multi-objective mathematical programming model for the problem is formulated, and it is shown that the problem is NP-hard. Two new meta-heuristics are designed, one is guided variable neighbourhood search (GVNS) combined with harmony search, and the other is GVNS combined with simulated annealing. Compared with enumeration algorithm, tabu search, variable neighbourhood search (VNS), harmony search, extend next fit decreasing (ENFD) and skewed VNS (SVNS), variable neighbourhood descent (VND), the numerical results by actual production data have shown that the proposed model and GVNHS are feasible and effective for ICP.

Design and implementation of an automated secondary cooling system for the continuous casting of billets

This paper describes a heat transfer model based automatic secondary cooling system for a billet caster. The model aims to minimize the variation in surface temperature and excessive reheating of the billet strands. It is also used to avoid the low ductility trough of the solidifying steel, which aggravates the tendency of steel to crack. The system has been designed and implemented in an integrated steel plant. A Programmable Logic Controller (PLC) based automation system has been developed to control the water flow in the secondary cooling zones of the strand. The results obtained through field trials have shown complete elimination of internal and off-corner cracks for the fifty billet samples that were monitored.

Desulphurization and Simultaneous Treatment of Wastewater from Blast Furnace by Pulsed Corona Discharge

Laboratory tests were conducted for removal of SO2 from simulated flue gas and simultaneous treatment of wastewater from blast furnace by pulsed corona discharge. Tests were conducted for the flue gas flow from 12 to 18 Nm3/h, the simulated gas temperature from 80 to 120°C, the inlet flux of wastewater from 33 to 57 L/h, applied voltage from 0 to 27 kV, and SO2 initial concentration was about 1,430 mg/m3. Results showed that wastewater from blast furnace has an excellent ability of desulphurization (about 90%) and pulsed corona discharge can enhance the desulphurization efficiency. Meanwhile, it was observed that the SO2 removal ratio decreased along with increased cycle index, while it increased as the flux of flue gas was reduced, and increased when the flux of wastewater from blast furnace was increased. In addition, results demonstrated that the content of sulfate radical produced in wastewater increase with an increment of applied pulsed voltage, cycle index, or the flux of flue gas. Furthermore, the results indicated that the higher the inlet content of cyanide the better removal effect of it, and the removal rate can reach 99.9% with a residence time of 2.1 s in the pulsed corona zone during the desulphurization process when the inlet content was higher, whereas there was almost no removal effect when the inlet content was lower. This research may attain the objective of waste control, and can provide a new way to remove SO2 from flue gas and simultaneously degrade wastewater from blast furnace for integrated steel plants.

Spatial and temporal variation of mercury load in surface water and sediments around an integrated steel plant in India

Coal burning in the steel industry is the chief source of mercury presence in surrounding environment. About 20 water-storage ponds and three natural water streams are located in adjoining areas of an integrated steel plant in Bhilai, India. Hundreds of hospital admissions with chronic ailments due to hazardous emissions from the steel industry are frequently reported. Many of these ailments are related to reported mercury-poisoning diseases. Measurements of mercury levels in various environmental matrices around this industrial area was started early in the 1990s. From 1990–1995, few environmental samples were analyzed for mercury content but from 1995 onwards, comprehensive assessment of mercury load along with other toxic metals in various environmental matrices were begun. This work synthesizes and compares data of mercury in the surface water from three major field programs, in 1997, 2002, and 2006. The focus is on both spatial and temporal variation. In the present survey (2006), mercury levels are significantly higher compared to subsequent surveys and have shown 10–18 times higher values compared to 2001 and 1997 surveys. The differences in Hg levels between downwind and other sites in three survey programs are found to be in order: 1997 > 2001 > 2006. Regression between water and sediment mercury levels has shown variation in correlation values and higher in winter season.

Virtual indurator: A tool for simulation of induration of wet iron ore pellets on a moving grate

Pelletization of iron ore fines is an important step in an integrated steel plant. It essentially involves balling of fine powders on a rotating disk or drum to produce wet pellets and induration on a moving grate to produce fired pellets. The development of a user-friendly simulation tool, virtual indurator, for induration is presented here. The simulator is based on a phenomenological model of induration. The mean diameter and moisture content of wet pellets, composition and temperature of inlet gas, firing hood temperature profile, pellet bed and hearth layer heights, and furnace design parameters such as grate length are used as model inputs. The model predicts bed and gas temperature and composition profiles, burn-through point temperature and its location, etc. This simulator can be utilized for improving furnace productivity, for optimizing fuel costs and as an operator training simulator.

Granulometric optimisation of raw materials for ISF continuous segregation system in Usiminas' sintering plants

This paper describes the improvement in the operational results obtained in the sintering unit of Usiminas' Steel Works, located at Ipatinga, one of the integrated steel plants in Brazil, after incorporation of intensified sifting feeder in the sintering circuit. Beneficial results came about after extensive investigations involving alterations to particle sizes of the feed material comprising of different types of iron ore, limestone, solid fuels and other additives such as serpentinite. The present work describes the methodology developed for sampling, including variations in the particle sizes of the feed mix, and their effect on the operational results of the sinter plant in respect of productivity and quality of sinter produced. The beneficial effect of serpentinite additions has been confirmed.

Comparative study on different steel slags as neutralising agent in bioleaching

A comparative study on bioleaching of a pyrite concentrate using five different steel slags as neutralising agent has been performed with reference to a commercial grade slaked lime. The acid produced during oxidation of pyrite was neutralised by regular additions of neutralising agent to maintain a pH of 1.5. Bioleaching was conducted as batch in 1-L reactors with a mixed mesophilic culture at a temperature of 35 °C. The different steel slags used were Argon Oxygen Decarbonisation (AOD) slag, Basic Oxygen Furnace (BOF) slag, Electric Arc Furnace (EAF) slag, Composition Adjustment by Sealed Argon Bubbling–Oxygen Blowing (CAS–OB) slag and Ladle slag, representing slags produced in both integrated steel plants and scrap based steel plants. The aim of the study was to investigate the possibility to replace normally used lime or limestone with steel slags, considering their neutralising capacity and eventual toxic effects on the bacterial activity. The bioleaching efficiency was found to be equally good or better, when steel slags were used for neutralisation instead of slaked lime and the extent of pyrite oxidation of pyrite was in the range 75–80%. Some of the slags used contained potentially toxic elements for the bacteria, like fluoride, chromium and vanadium, but no negative effect of these elements could be observed on the bacterial activity. However, slags originating from stainless steel production are less environmentally friendly due to the presence of chromium. The neutralising potential of the slags was high, as determined by the amount needed for neutralisation during bioleaching. The range of additions of neutralising agents required to control the pH at 1.5 for all the experiments ranged from 16–27 g, while 22 g was needed in the experiment with slaked lime. Hence, it was concluded that considerable savings in operational costs could be obtained by replacement of lime or limestone with steel slag, without negative impact on bioleaching efficiency. Recycling of steel slags would render an eco-friendly process and provide a means for sustainable use of natural resources.

Operating experiences with Corex and blast furnace at JSW Steel Ltd

JSW Steel Ltd is an integrated steel plant of 3·8 mtpa capacity, with two Corex and two blast furnace (BF) units for producing hot metal. It has started its integrated steel plant operation with Corex ironmaking technology and then synergised with the conventional BF ironmaking during plant expansion. Both these ironmaking furnaces are unique in nature, and have different operation philosophies. The performances of these units depend on the raw material charged, operational philosophies, maintenance, etc., and have their own advantages and disadvantages. This paper brings out the comparison between these ironmaking processes through the usage of raw material inputs, plant operation, maintenance, quality of hot metal and byproducts. This paper also highlights the benefits due to synergistic combination of Corex and BF in an integrated steel plant.

Economies of scale in global iron-making

In this paper, we investigate the presence of economies of scale in the global iron-making industry for integrated steel plants, iron making being the first stage in the steel-making process. Iron making depends on basic commodities, such as iron ore, coke and various forms of energy, required in the operation of the blast furnace, which can be classified as essential inputs and used in fixed proportions to produce iron. A generalized Leontief cost function is estimated using panel data for 69 integrated plants, such a specification being appropriate for technologies with essential inputs that are used in fixed proportions in production. A significant scale effect is observed due to the existence of fixed costs and a linear dependence of the cost function on production. Under a simple linear cost function, a rough estimate of the breakeven scale of plant, where costs equal revenue, is 4.5 Mt per year. Competitiveness, as measured by the ratio of plant average cost per tonne to best practice cost per tonne, can be shown to be positively related to the scale of production as well as the cost of essential inputs. Therefore, low-cost producers are also often producers with low raw material costs and production levels below the estimated breakeven scale of operation. Labor costs, although significant, are comparatively less important as a driver towards low costs.

¿Proyecto faraónico o chivo expiatorio? La IV Planta Siderúrgica Integral de Sagunto (1966-1977)

The aim of this article is to analyse the reasons for the creation of the Fourth Integrated Steel Plant in Sagunto. Using primary sources, we demonstrate that it was a rational decision that imitated the experience of other developed countries. This decision was based on a market study that failed in its steel consumption forecast. But such error was not due to the imperial dreams of Franco's regime, but to the unforeseeable character of the 1970's economic crisis and its effects on the steel industry.

Scunthorpe Steelworks 1973–2006: a history of continuous development Part 2 – Process and product developments

The first part of this review gave a strategic overview of the local and world events that helped shape Scunthorpe Steelworks since 1973. The key issues were getting to grips with operating new plant, drastic cost cutting in a dire economic environment, yet simultaneously having to develop new products as traditional markets declined and new opportunities were generated. The present paper describes the initial post-commissioning of the plant in 1973 and how, because of the poor general financial state of the UK steel industry, capital funding for big projects was limited, so developments to reduce costs, improve quality and increase output were dominated by incremental spending rather than spending on major capital schemes.Significant changes to capital plant, process routes, product range and quality have occurred. The Works remains one of the premier integrated steel plants in Corus and, as a major £130m investment programme is completed, it is set for a significant role in future company strategy.