Feasibility Study of Reducing the Level of Environmental Risks Caused by the Wastes Produced in MIDREX Steel Direct Reduction Plants

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Abstract

In recent year, developments have been associated with increased population, different economic developments, improvement in human life and technology has led to a new phase of destruction of nature and environment, especially in the field of waste. Obligating industries to implement waste management program and to plan to dispose the waste correctly, is necessary to achieve sustainable development. Present study aimed to determine the risk of waste management of direct reduction plant, in Sirjan Jahan Foulad Complex and to provide the strategies to reduce the level of risk. So, in present study, firstly, waste compound was identified and then, the management of each waste was identified, risk assessment was performed using general approach and corrective measures were defined in order to reduce the risk of wastes. According to the results, Pellet fines, oxide sludge, sponge iron cluster, sponge iron fines, catalyst, etc. were identified and after performing risk assessment, it was found that the risk of wastes was mostly acceptable with the need for corrective measures and following strategies were suggested to reduce the risks: source separation, recycling, training all the personnel, formation of solid waste management committee, development of waste management guidelines and management practices such as reducing the wastes, systematic control of materials, reducing the size of devices and improving them.

Introduction

Industrial processes turn raw materials and resources into products in unchanged way and during these processes, some types of wastes are created as energy and matters. If these wastes aren’t managed properly and discharged into the environment, they may become pollutants [1]. In recent years, environment and waste, as important issues, have been of particular interest of people in the world. Establishment of waste collection and disposal management system is of major issues in controlling the production, saving and consuming materials and also trash collection and disposal process. The efficiency of this system should be consistent with health, economy and environmental engineering also, be planned in accordance with other general conditions in society [8]. The term “industrial waste” refers to all the wastes produced during industrial operations of production. These wastes are usually classified into two groups of ordinary wastes and hazardous wastes. Now, industrial activities are the main source of hazardous waste in the world. According to the United Nations Environment Program, hazardous wastes (solid, liquid or sludge) are referred as the wastes except for radioactive wastes which cause potential and actual risks to human health and the environment due to their chemical properties, toxicity, explosivity, corrosivity or other characteristics. So, diverse characteristics of hazardous wastes make the problem of waste management complex. Now, the main elements of comprehensive waste management are production, storage, collection and transportation, processing, disinfecting, disposal and after care of it. Background of industrial waste management returns to approval of Resource Conservation and Recovery Act (RCRA) in the United States of America [3]. Limited resources and the need to protect the environment has led that industrial waste management has been considered as one of the important environmental solutions. Now, industrial activities are the main source of hazardous waste in the world [2]. In [6], the results showed that the wastes produced in direct reduction plant, are recyclable and special industrial wastes (soft sponge iron, construction dirt and debris and different types of sludge waste) and domestic sources (ordinary waste, waste produced by the streets, pathways and trash cans, pruning the plants). According to the results, superior strategies were prioritized to manage the waste and then, based on it, management practices, including source separation, collection and transportation, sorting and storing, disposal, sale, recycling, education and awareness about the waste management have been proposed. In recent years due to the increasing need for Iran to steel sections, the project of Sirjan Jahan Foulad Complex, located in Gol Gohaer, mining and industrial area, was started with the aim of producing one million tons of sponge iron through MIDREX direct reduction method. MIDREX direct reduction method is one of the methods used to produce sponge iron, as the main feed of steel-making section. Since this method has been localized in Iran, it is increasingly used in most steel development projects. According to the studies conducted, the major wastes produced in this units are oxide sludge, pellet fines and sponge iron cluster. Pellet fines and oxide sludge are produced by handling materials to oven and also, oxide sludge is produced by dredging clarifiers, servicing to gas scrubber in production process and dust collectors in material handling system in the direct reduction unit. They have the largest share of industrial waste in the plant. Catalysts used in reformer can be referred as another waste produced in the plant. It consists of nickel and magnesium which are considered as hazardous waste. So, present study aimed to identify waste compound – to identify how to manage each of waste – to conduct risk assessments through General Approach and to define corrective measures to reduce the risk of wastes.

Conclusion and suggestions

There are three risk levels of “unacceptable”, “acceptable with the need for corrective measures” and “acceptable”. After performing related analyses, it was concluded that the risk level of waste management in Sirjan Jahan Foulad Complex, was mostly acceptable with the need for corrective measures.

In most cases, the risk can be reduced by substituting low-risk materials. This results in reduced wastes. Changing formulation of product is of difficult methods used to reduce the wastes. By separating toxic, hazardous and recyclable materials from the waste materials, the size of waste is reduced in addition to its increased recyclability.

Correcting devices deployed in production line or replacing them with modified them can be a good strategy for reducing waste production.

Systematic management and control of raw materials, intermediate and final products can be effective in reducing and controlling the wastes.

References

  1. Abbaspoor, M., 1992, Environmental Engineering, Volume I, Tehran, Islamic Azad University.
  2. Alqaydi S., 2006, Industrial solid waste disposal in Dubai, UAE: A study in economic geography Cities. 23:140–148.
  3. Basim, Y., Jafarzadeh, N., 2009, The environmental pollution control in direct reduction projects at construction and exploitation stages (Direct Reduction Project, Iran National Steel Industrial Group), the third professional conference on Environmental Engineering, Tehran, Tehran University, Faculty of environment
  4. LaGrega M, Buckingham PL, Evans J C., 2001, Hazardous waste management. 2rd New York: Mc-Graw Hill publication.
  5. Mokhtarani N., 2007, Hazardous Waste Management. 1nd ed. Tehran: Sharif University Pub [Persian].
  6. Monjezi, S. et al., 2012, Waste management in Iran steel industries and provision of appropriate management strategies, Case study: MIDREX direct reduction plants, the sixth national conference and the first International Conference on Waste Management, Mashhad, Iran’s Municipalities and village administrators.
  7. Mrayyan B, Hamdi M R., 2006, Management approaches to integrated solid waste in industrialized zones in Jordan: A case of Zarqa City. Journal of Waste Management. 26:195- 205.
  8. Omrani, Q., 2004, Solid waste, Islamic Azad University Press, Volume 1 and 2, Tehran

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