Technical Market Support

Behaviour of Coal Injected into Molten Baths

Technical Market Support » Metallurgical Coal

Published: May 00Project Number: C5061

Get ReportAuthor: David Langberg, Xun Liu, AK Kyllo | GK Williams CRC, CSIRO Minerals

During the past 30 years there has been a major trend in the metallurgical industry towards the use of high intensity bath smelting reactors for large-scale production of metals. Coal is commonly used as a fuel and/or reductant in these reactors.

GK Williams Cooperative Research Centre for Extractive Metallurgy undertook this project to improve understanding of the behaviour of coal and the importance of coal properties in the coal injection process and subsequent bath smelting reactions.

The sponsors were ACARP, Ausmelt, Pasminco, WMC and Rio Tinto. The project commenced on 1 July 1995.

The project aims were to predict and interpret the performance of slag bath reactors using coal as the reductant and to determine the relative importance of coal properties to the performance of slag bath reactors. A combination of experimental work and mathematical modelling of molten bath reactors was used to meet the project aims.

A generic PC-based model for slag bath reactors was developed which can be tuned to particular reactors using plant trial data. The slag fuming version of the model was tuned to the operation of the Pasminco, Port. Pirie, No.1 slag fumer.

Experimental investigations were carried out on coal devolatilisation at bath smelting temperatures, the interfacial reaction rates between fumer slags and gases derived from the submerged combustion of coal with slags, and the reduction rates of slags by coal chars and other carbons.

The key experimental findings are:

Impact of slag viscosity: The particle velocity required for capture of injected coal increases with increasing slag viscosity and decreases with increasing particle size and density. It can be predicted using a dimensionless plot based on a dynamic force balance model developed in the project.

Volatiles yield: The actual volatiles yield for short heating times is determined by the devolatilisation rate and may be significantly less than the proximate volatiles.

Mass transfer limitation: The gases in zinc slag fumer plumes during normal operation are oxidising relative to the slag bath. The interfacial oxidation reaction is likely to replace gas phase mass transfer as the rate limiting step for oxidation of the bath by the plume bubble (for bubble sizes less than about 0.01 m).

Liquid phase mass transfer: The reduction rate of FeO by solid carbonaceous reductants in iron making slags containing less than 20% FeO is controlled by liquid phase mass transfer between 1300 -1375?C.

Ferric oxide reduction: The ferric oxide reduction rate of a typical non-ferrous (high iron content) smelting slag by coal added to the bath is directly proportional to the char yield of the coal measured by heating to 1400?C but is apparently independent of the proximate properties of the coal.

Carbon content: The fixed carbon content of the coal is the most important factor affecting reduction efficiency.

Reduction efficiencies: High fixed carbon coals are predicted to give the highest reduction efficiencies. For these coals, a high entrainment rate is also desirable.

Entrainment: High entrainment will increase efficiency and reduce the excess heating effect that occurs due to the higher available heat from the coal. However, this does not take into account the lower reactivity of the high carbon coals which may increase the amount of coal bypassing the furnace.

Lower fixed carbon content: For coals with a lower fixed carbon content, the PC-based modelling predicts an optimum entrainment rate which is related to the heating value of the coal.

Moisture and ash: Reduction efficiency is improved by the reduction of both the moisture and ash contents of the coal. This is primarily due to the corresponding increase in the fixed carbon content that this represents.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C27052Site Trial And Demonstration Of Integrated Forward And Reverse Osmosis For Mine Water Reuse

The forward osmosis (FO) process, also known as direct osmosis, is a...

C28022Development Of A Simple Rotary Steerable System For Underground Inseam Drilling

The purpose of this project was to complete the design and testing o...

C21002Measurement And Reporting Of Fugitive Emissions From Underground Coal Mines

The National Greenhouse and Energy Reporting Act 2007 (Act), the ...


Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C28034Mining Equipment Human Factors Design For Workforce Diversity

The objectives of the project were to:

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27025Quantifying The Step-Change Benefit Of Reflux Flotation Cell Circuits

The objective of this project was to quantify the value proposition ...

C24047Characterisation Of Pressure (Hyperbaric) Filter Performance

Hyperbaric disc filter technology has been used to dewater fine coal...

C28058Phase Two Development Of A Low Cost Online Measurement Of Particle Size And Density For Diagnostics Across The Fine Coal Circuit (Particle Profiler)

This project is based around the development of a prototype system (...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C26039Nanoporosity In Cokes: Their Origin, Control And Influence On CO2 Reactivity

This project using the outcomes of previous project C24060, examine...

C28063A Comprehensive Technical Review Of High-Efficiency Low-Emission (HELE) Pulverised Coal Combustion Technologies For Power Generation

Research and development has been undertaken worldwide to realise co...

C28064Carbon Structure Transformation During Coking Of Australian Coking Coals: Better Understanding The Coke Formation

Carbon structures of coke that are formed during the plastic layer a...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

C26004CFD Modelling Of Reverse Thermal Oxidisers For VAM Abatement - CFD Modelling Of Fixed-Bed RTO Devices

The project is part of a larger multi‐phase program of study a...

C27058Technological Assessment Of A Recycle Reactor For VAM Abatement

Underground coal mining emits high volumes of methane, diluted in ve...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community


National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook