ACARP ACARP ACARP ACARP
Coal Preparation

Options For the Addition and Control of Non-Magnetic Material in the Correct Medium

Coal Preparation » Gravity Separation

Published: June 20Project Number: C24050

Get ReportAuthor: Michael O’Brien | CSIRO

The non-magnetic concentration in the correct medium is important, particularly at correct medium densities below RD 1.4 where the Dense Medium Cyclone (DMC) differential - which is the difference between the density of the underflow medium and the overflow medium - may be too high. This can produce instability in the cyclone operation, and the loss of valuable coal.

The addition of non-magnetics to the correct medium, increases the volume concentration of fine particles, allowing particle inter-particle interactions and hindered settling which stabilises the medium, and decreases the differential. Nominally a differential of between 0.2 and 0.4 (Crowden et al. 2013) should be maintained, although this is not a hard figure, as some cyclones operate outside of this range without issues. Generally if the differential is above 0.4, excessive separation of medium can take place in the cyclone, and the cyclone  can become unstable. Below 0.2, viscosity issues in the correct medium can prevent good separation, particularly of the finer particles which will result in loss of coal to the reject, and/or reject material in the product.

This project examined methods that can be used to maintain the concentration of non-magnetics in the correct medium at a level that promotes medium stability, approximately 20% by weight in the correct medium solids, (O'Brien et al. 2014). The most prospective method found  was to control the addition of the non-magnetic material from the thickener underflow using a control valve with inputs from the nucleonic density gauge anda magnetite monitor which provides the concentration of magnetite in the correct medium and allows the calculation of the percent non-magnetics in the medium.  The cyclone differential which is available online from electrical impedance spectrometers in the drain sections of the product and reject screens  is also monitored and used as an input to the control system  

A system was installed at a coal preparation plant and operated over a 12 hour period with regular controled  on and off periods. Despite the influence of feed changes and bleed valve changes which will effect the non-magnetic concentration in the correct medium the system performed as expected with the amount of non-magnetics material increasing when the system was on and decreasing when the system was off.  

It is recommended that this type of system be employed where low densities of separation are common and medium instability is an issue. By controlling the bleed valve from this system highly viscous mediums with differentials below 0.2 could also be controlled to maintain a “healthy” differential without loss of coal.

Underground

Health and safety, productivity and environment initiatives.

Underground

Open Cut

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

Recently Completed Projects

C19024Establishing Ecologically Sustainable Mine Water Release Criteria In Seasonally Flowing Streams

Extreme rainfall conditions in the Fitzroy Catchment over an approxi...

C25030Coal Mine Open Pit Final Void Closure And Relinquishment - Addressing Uncertainty In Coal Mine Environmental Planning

This report addresses uncertainties faced by coal mine operators whe...

C27046Estimation Of True Deformation Vector From Slope Radar Monitoring

Slope deformation radar monitors are now widely used in open cut coa...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27004Improving Coal Flotation With Oscillatory Air Supply

This report provides detailed information on coal flotation with os...

C25018Improving Solids Recovery And Moisture Reduction In Ultrafine Coal Dewatering

This report provides detailed information on fine coal dewatering in...

C27028Lab Froth Flotation Testing Guide With Coal Quality

Correct outcomes from laboratory froth flotation testing in coal bor...

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

NERDDC

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

NERDDC