دانلود رایگان ترجمه مقاله روش های نوآورانه برای پردازش بهینه سرباره های متالورژیکی (سال ۲۰۱۴)

روش های نوآورانه برای پردازش بهینه از سرباره های متالورژیکی

Innovative approaches for an optimized processing of metallurgical slags

Abstract

Metallurgical slags are produced in large quantities all around the world as a result of smelting, refining or  alloying  processes  applied  to  metals,  ores  and  recycling  material.  The  slag  phase  serves  different purposes  in  metallurgical  processes.  It  prevents  heat  losses  and  protects  the  metal  phases  from contaminations and absorbs gangue and extracted impurities. Due to achievable metallurgical efficiencies certain  amounts  of  valuable  metal  contents  always  remain  in  the  residual  slag.  Recycling  of  these metallurgical  slags has  several positive effects, such  as  optimized ecological  and economical compliance of the producing industry. If recycled metal contents can be reintroduced into existing processes, required inputs of raw material can be lowered. High metal prices enable the economic recovery of metal contents in  metallurgical  slags  by  applying  different  non­metallurgical  processing  methods.  Conventional processing  of  metallurgical  slags  utilizes  processes  such  as  hand  picking,  selective  comminution, screening and magnetic separation. Those state of the art processing techniques have limitations in terms of achievable metal recoveries and required energy demand. The approach for an optimized processing of metallurgical slags targets enhanced metal recoveries in combination with lower specific treatment costs. Processes  such  as  coarse  and  ultrafine  density  separation,  as  well  as  sensor­based  sorting  as  a  preconcentration stage are used to enable an efficient recovery of metal contents in slags. By applying these methods a completely dry working process is possible. This paper reviews the commonly used methods and  describes  approaches  for innovative  processing  of  metallurgical  slags  to  enhance metal  recoveries. Focus of this paper is laid on sensor­based sorting as well as on processes for dry density separation.

۱ Introduction

In a situation of steadily increasing demand for raw materials, the issue of how to use our resources most efficiently is a contentious economic and environmental political issue today. A combination of sustainable exploitation and use of primary resources in combination with an optimized handling and processing of secondary resources, such as metallurgical slags is the key for a better handling of existing resources.

Metallurgical slags are by­products from metal extraction, refining and alloying processes and are produced in significant amounts. The slag phase is used to encapsulate impurities and additives added during casting and alloying processes for further purification of metals. Besides impurities, slags usually contain significant amounts of metal contents (Van Oss, 2002). A suitable recycling and reintroduction of such metal contents and non­metallic slag residues is highly desirable but, yet, not always applied. Besides recycling of metallurgical slags in existing processes, the recycling of old dump sites is important. If not properly recycled and reintroduced into the raw materials cycle as new products, an important resource is lost. Numerous technologies exist which differ in terms of costs and efficiency. Applied state of the art technologies for recovering metal contents from slags include, for example, selective comminution, wet and dry density separation, magnetic separation, dense media separation or combinations of the proposed techniques. However, metal recoveries, especially for fine, intergrown metal contents as well as energy and resource efficiencies are low for many applied processes. In many cases, the fine fraction is not even treated and discarded as waste material (Wotruba, Weitkaemper, 2013).

This paper reviews current application fields for metallurgical slags. Applied technologies for recycling and recovering of metal contents and non­metallic compounds, with emphasis on mechanical processing technologies are described, and new approaches for a more economical, environmentally and therefore sustainable treatment with focus on stainless steel slags on a dry basis are introduced.