Project Reference: Optimising Cemented Paste Fill using MasterRoc MF 505C

Location: Western Australia
Market sector: Underground Construction
Products used: MasterRoc MF 505C a concentrated polymer admixture used to improve cementitious mining backfill mixes

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The Background

Darlot Gold Mine, operated by Gold Fields Australia, is situated 120 kilometres north of Leonora and 58 kilometres east of Leinster in the Yandal Greenstone Belt (Western Australia). Darlot underground complex utilises paste fill to provide static support for all voids in Lode 1. The required paste strength and cement content vary depending on the planned exposure. Curing time is also dependent on the mix used. Historical curing times for undercut and side exposures are approximately 20 days Current practice has paste development for mixes with cement content ≥2.5% undertaken at 4 days after finishing paste fill.

The Challenge

Darlot required a faster mining cycle to mine the new ore body efficiently. Master Builders Solutions was engaged to assist with the improvement of the paste fill mix utilising chemical admixtures. Paste development and exposure from stoping commenced early to avoid cement content being reduced. Based on laboratory and site-based trial results, MasterRoc 505C was added to all Stage one (plug) pours in Lode 1 as the first pour with chemical addition began in April 2017.

Our Solution

Laboratory and large-scale (site-based) trials were undertaken using MasterRoc MF 505C with aim of increasing the quality of paste fill, in order that paste development, side exposure and undercut curing times could be reduced and Lode 1 extraction rate increased. The greatest strength gain was observed within the 14 – 28 day undercut curing window, with 400ml per wet tonne chemical addition. Based on trial results to date, the addition of MasterRoc MF 505C to paste fill mix will allow a two-day reduction in undercut curing time compared to LOM plan.

Project Facts at a Glance

1 – 7 Days early entry when mining against the paste with MasterRoc MF 505C

Ability to transport paste longer distances with the addition of the MasterRoc MF 505C

Cement reduction of 1% can be obtained if paste exposure is not time-constrained.

Strength increase of 16% with the inclusion of the MasterRoc MF 505C

Product Facts at a Glance

MasterRoc MF 505C admixture aids in the production of backfill mixes by reducing water content for a given consistency and increasing compressive and flexural strength
Greater economy in a mix designed for a given strength, slump and air content
Cost savings and increased durability

Customers Benefit

From test results, the addition of MasterRoc MF 505C to paste mix allowed for a 2% reduction in water; the optimal dose rate being 400ml per wet tonne. Increased flowability of the mix was demonstrated through slump results with the addition of MasterRoc MF 505C. A reduction in the number of lumps within the paste occurred with the inclusion of the MasterRoc MF 505C. Due to this, time savings were achieved for undercut exposures.

​​​​​Project Reference: Optimising Cemented Paste Fill using MasterRoc MF 505C​