Design and Application of Underground Mine Paste Backfill Technology

Abstract

This paper reviews the design and application of paste backfill in underground hard rock mines used as ground support for pillars and walls, to help prevent caving and roof falls, and to enhance pillar recovery for improved productivity. Arching after stope filling reduces vertical stress and increases horizontal stress distribution within the fill mass. It is therefore important to determine horizontal stress on stope sidewalls using various predictive models in the design of paste backfill. Required uniaxial compressive strength (UCS) for paste backfill depends on the intended function, such as vertical roof support, development opening within the backfill, pillar recovery, ground or pillar support, and working platform. UCS design models for these functions are given. Laboratory and backfill plant scale designs for paste backfill mix design and optimization are presented, with emphasis on initial tailings density control to prevent under-proportioning of binder content. Once prepared, paste backfill is transported (or pumped) and placed underground by pipeline reticulation. The governing elements of paste backfill transport are rheological factors such as shear yield stress, viscosity, and slump height (consistency). Different models (analytical, semi-empirical, and empirical) are given to predict the rheological factors of paste backfill (shear yield stress and viscosity). Following backfill placement underground, selfweight consolidation settlement, internal pressure build-up, the arching effect, shrinkage, stope volume, and wall convergence against backfill affect mechanical integrity.

Strength Characteristics and Failure Mechanism of Cemented Super-Fine Unclassified Tailings Backfill

“…Underground mine backfill technology, one of the most important mining methods in the world [1], has developed rapidly since 1960s [2][3][4][5] due to the fact that it can control ground collapse, reduce ore dilution, reduce risk of barricade failure and enable mine operations to lessen the quantity of wastes [6][7][8][9]. Currently, cemented past backfill (CPB), which is made of mill tailings generated by the mineral processing plant, a binding agent such as ordinary Portland cement (OPC), water and other additives, is the most frequently used filling material due to its economic, environmental and technical benefits [10][11][12][13][14][15].…”

Strata behavior at fully-mechanized coal mining and solid backfilling face

“…Domestic and foreign scholars have done a lot of research and practice on it. Varieties of backfill mining methods such as solid backfill, pneumatic backfill, cemented paste backfill and high-water material backfill have been put forward (Tapsiev et al 2009; Belem and Benzaazoua 2008; Seryakov et al 2008; Donovan and Karfakis 2004; Rankine and Sivakugan 2007). One of the most extraordinary among them applied in China is the fully-mechanized backfill mining (FMBM) (Ju et al 2009; Zhang and Miao 2006).…”

A modified solution to assess the required strength of exposed backfill in mine stopes

“…A critical issue in backfill design is the determination of the minimum required strength for the primary stope backfill, which is now often made of a cemented paste (Belem and Benzaazoua 2008). The pioneering work of Mitchell et al (1982) has provided a practical solution for the problem of backfilled stopes with an exposed (unsupported) face.…”