Energy Consumption and Greenhouse Gas Emissions During Ferromolybdenum Production

Anders Tilliander,P\xe4r G. J\xf6nsson,Peter B. Samuelsson,Rutger Gyllenram,Wenjing Wei

doi:10.1007/s40831-019-00260-8

Abstract

Molybdenum is mainly used as an alloy material in the iron and steel industry and typically in the form of ferromolybdenum (FeMo). The current study aims to evaluate the energy consumption and greenhouse gas emissions (GHG) of four ferromolybdenum production cases using inventory inputs from a process model based on mass and energy conservations. The total energy required for producing 1 tonne of FeMo can vary between 29.1 GJ/t FeMo and 188.6 GJ/t FeMo. Furthermore, the corresponding GHG emissions differ from 3.16 tCO2-eq/t FeMo to 14.79 tCO2-eq/t FeMo. The main variances are from the mining and beneficiation stages. The differences in these stages come from the beneficiation degree (ore grade) and the mine type (i.e., co-product from copper mining). Furthermore, the mine type has a larger impact on the total energy consumption and GHG emissions than the beneficiation degree. More specifically, FeMo produced as co-product from copper mining has a lower environmental impact measured as the energy consumption and GHG emission among all the four cases. The inventory, consumed energy or associated GHG emission is independent on the initial ore grade and mine type in the downstream production stages such as roasting and smelting. Also, transport has the least impact on the energy consumption and GHG emission among all production stages.

Highlights

Molybdenum is widely used as an alloy material in the iron and steel industry, and in particular in the stainless steel industry, in the form of ferromolybdenum (FeMo)
Life cycle inventory (LCI) [4] is one of the execution steps in the life cycle assessment (LCA) to account for the energy and resource flow within a defined boundary
International Molybdenum Association (IMOA)’s LCI study regards each production stage as a ‘black box’ with input and output datasets from several production sites, which cover 30% of the world’s total molybdenum production

Summary

Introduction

Molybdenum is widely used as an alloy material in the iron and steel industry, and in particular in the stainless steel industry, in the form of ferromolybdenum (FeMo). Alloying with molybdenum contributes to a better corrosion resistance of iron and steel products. Cradle-to-gate life cycle assessment (LCA) [3] is a systematic tool developed for assessing the environmental aspects associated with a product from resource extraction to the factory gate. Life cycle inventory (LCI) [4] is one of the execution steps in the LCA to account for the energy and resource flow within a defined boundary. The International Molybdenum Association (IMOA) completed a life cycle inventory [1] for three molybdenum-containing metallurgical products (roasted molybdenite concentrates, ferromolybdenum, and technical molybdic oxide briquette). The consequent resource usage and environmental impacts results are reported as an industrial average level. For downstream customers like stainless steel manufacturers, lack of the plant-specific data on the molybdenum product results in

Results

Discussion

Conclusion