ACARP ACARP ACARP ACARP
Coal Preparation

Optimising the Performance of Tailings Dewatering in a Solid Bowl Centrifuges

Coal Preparation » Dewatering

Published: April 18Project Number: C25010

Get ReportAuthor: Rohan Stanger, Andrew Stanger, Quang Anh Tran, Wei Xie, Michael Stockenhuber, Eric Kennedy, John Lucas, Terry Wall | University of Newcastle

This tailings dewatering study was undertaken to provide a link between the fundamental tailings properties and observable bulk characteristics produced by a solid bowl centrifuge. Samples were taken from both a commercial and pilot scale unit operated at separate mine sites. This afforded the opportunity to analyse comparative samples from an existing belt press filter and investigate the impact of flocculent addition.

The commercial scale SBC unit was sampled across two campaigns and showed that cake moisture was relatively insensitive to changes in load and only marginally sensitive to flocculent dosing. The lowest achievable cake moisture was 32% at low polymer dosing and rose to 38% at high dosing rate. The solids content in the centrate effluent was observed to change significantly with flocculent from 12% (low dosing) down to 0.8% (high dosing).

The pilot SBC unit samples were suppled from a different mine site and encompassed 7 different seams, of which 4 samples produced cake moistures under 45% (considered “good”) and 3 samples produced cake moistures in the range 45-60% (considered as “poor” dewatering). These samples were then selectively analysed to determine if any fundamental characteristics could be used as predictors for dewatering behaviour. The XRD results showed that all pilot feed samples were rich in SiO2 and kaolinite, but could not identify significantly different mineralogy between tailings of “good” and “poor” dewatering properties. It was observed that the 3 tailings samples with cake moistures had lower NaCl:clay ratios and this suggested that the presence of dissolved salts may impact on the settling/bed compaction within the SBC unit.

The greatest observable discrimination between tailings samples of good and poor cake moistures was the difference in particle size distribution between feed and cake. Lower moisture cakes (<45%) contained a lower amount of ultrafine particles below 10μm than the feed- indicating that these particles had been flocculated to larger size. Higher moisture cakes (>45%) contained significantly more ultrafine materials (relative to the feed). This was considered due to the degradation of particles undergoing high shearing conditions. Results from the SEM-EDS confirmed the presence of a number particle types but specifically observed agglomerated particles consisting of smaller (<5μm) alumina-silicate particles. These particles were considered to be the most likely to breakdown in high shearing conditions to produce ultrafine clay particles. The elemental composition of these agglomerated particles indicated that they contained a number of trace compounds (Na, Cl, K, Fe, S, Mg) suggesting a complex mineralogy.

A laboratory method was developed to capture dewatering characteristics during accelerated gravity. The intention was to provide a controlled procedure to compare settling rates and bed compaction, ultimately providing a cake moisture indicative of the pilot unit. The method was able to replicate cake moistures within ±3% for tailings with good dewatering potential, but could not replicate the higher cake moistures from the 45-60% results. This was considered to be due to the lack of high shearing conditions that cause the degradation in particle size. Further work is needed in replicating this aspect of the solid bowl centrifuge.

Comparative samples from the pilot SBC unit and the existing Belt Press Filter indicated that similar cake moistures and effluent solids content could be obtained from tailings with “good” dewatering

potential. However, the SBC unit produced drier cakes (8-12% lower moisture) from 2 difficult tailings feed samples. This indicated that the SBC unit may be better suited for problematic feeds over a Belt Press Filter unit. Other comparative samples involved the use of a different flocculent (high molecular weight polymer) and the addition of a coagulant. Both the high MW polymer and the coagulent produced marginally drier cakes (3% lower moisture).

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