Rock Preconditioning Application in Virgin Caving Condition in a Panel Caving Mine, CODELCO Chile El Teniente Division

Morales, Ricardo; Henriquez, Jaime; Molina, Rigoberto; Araneda, Octavio; Valdivia, Eduardo

doi:10.36487/acg_repo/711_8

Cited by 9 publications

(7 citation statements)

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“…Preconditioning by hydraulic fracturing in other operations such as Inca Central West of El Salvador Mine and Diablo Regimiento of El Teniente Mine (CODELCO) have been well described by Chacon et al (2002), Chacon et al (2004), Araneda et al (2007), Araneda and Sougarret (2008) and Molina et al (2008).…”

Section: A Brief Review Of Preconditioning Techniquesmentioning

confidence: 94%

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Evaluation of intensive preconditioning in block and panel caving – part II, quantifying the effect on seismicity and draw rates

2017

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A combination of preconditioning by hydraulic fracturing and confined blasting referred to as intensive preconditioning was implemented at a major panel caving operation. The aim is to alter rock mass behaviour in a manner that could improve caving mechanics and extraction performance. A benchmark study involving data collected from operations in Chile, South Africa and Australia was carried out to investigate the hypothesis that operational data such as induced seismicity and draw rates could provide a quantitative measure of the impact of different preconditioning techniques. Analysis using Gutenberg and Richter (G-R) curves indicated that a massive and competent rock mass without preconditioning presents an induced-mining seismicity behaviour that is less favourable than a rock mass with intensive preconditioning, in other words, seismic events were shown to be more regular, numerous and their magnitudes higher than in the case where intensive preconditioning was applied. From draw rate data, analysis showed that the application of intensive preconditioning could improve draw rates by 15-28%, with relative differences of up to 38%. It is also important to note that this improvement in performance is achieved in a confined condition and at depths relatively greater than most block and panel caving operations.

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Section: A Brief Review Of Preconditioning Techniquesmentioning

confidence: 94%

“…between February and March 2005). Production started in September 2005 and the breakthrough was reported in July 2006 (Araneda et al, 2007). According to the information provided, the mining-induced seismicity as well as the production rates during the breakthrough process are presented in Figure 9.…”

Section: Seismic Behaviour At Cave 2 Panel Caving Area Chilementioning

confidence: 99%

Evaluation of intensive preconditioning in block and panel caving – part II, quantifying the effect on seismicity and draw rates

2017

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“…A drawbell is a funnel for broken rock that allows the extraction of the rock, connecting the undercut level, where the rock mass starts breaking, with the production level of block caving mines allowing the rock to flow within drawpoints (Bustos 2022). In a post-undercutting method (Rojas et al 2000; Brown 2007), the final drawbell geometry is created from the undercut and production levels in two stages. The first part of the shape is called drawbell excavation within this paper (Figure 1).…”

Section: Geometry Descriptionmentioning

confidence: 99%

Geotechnical analysis of blasting sequence and resulting shapes of drawbells in block cave mines

2023

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Drawbells allow disassembled ore to be extracted from the production levels in block cave mines. As part of the construction process, blast damage must be minimised, enabling the remaining rock mass surrounding the drawbell to sustain the induced stress during the different stages of a block-caving operation for a successful mine plan extraction and ore recovery.This paper proposes two approaches for the geotechnical evaluation of drawbell blast performance. Initially, the expected dynamic burden is calculated along the length of the blasthole and used to assess surveyed blast holes. Secondly, the design compliance is evaluated using the Radial Distance of Over/Underbreak concept, which compares designed and scanned shapes relative to height and radial orientation.The results have identified confined blast zones at the top and around the corners of drawbells. Excessive confinement may cause damage to the pillars and negatively impact the stability of the production level.

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“…Following this first industry experience in Northparkes in 1997, several other cave mines have applied pre-conditioning over time to introduce innovations to the caving process by combining hydraulic fracturing with confined blasting (Catalan et al 2017) or combining undercut variant and hydraulic fracturing (Pardo & Rojas 2016). These efforts have focused on applying pre-conditioning and positive outcomes in terms of a better seismic response (Morales et al 2007), cave propagation (Catalan et al 2017) or fragmentation (Brzovic & Gonzalez 2019). Even though these results have been successful, the fundamental concepts and models were taken from the experience of oil and gas, but further opportunities for improvement under different geotechnical conditions and deeper cave mining need to be investigated, and new applications identified (Rimmelin et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Modelling of fracture initiation near a cave back and its implications for hydraulic fracturing concurrent to cave mining

Rimmelin¹

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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Rock mass pre-conditioning has been applied in the mining industry since it was first trialled at Northparkes in 1997, to continue its wide application in large cave mines such as Cadia East and El Teniente mines. The most known application is based on hydraulic fracturing techniques transferred from the experience of the oil and gas industry to create additional fractures in the rock mass prior to initiating undercutting. In the mining industry, the aim is to reduce the rock mass quality to obtain an improved cave performance and other benefits such as better seismic response and reduced fragmentation. In addition to pre-conditioning, there are other experiences of hydraulic fracturing concurrent to an existing cave back. In this context, documented experiences from Northparkes, Grasberg and Cadia East mines were carried out by applying hydraulic fracturing to induce caving after a stalled or slowed cave propagation. Applications concurrent to cave mining do not follow the same rules as applied prior to undercutting (pre-conditioning) for fracture initiation and propagation. Furthermore, these have not been clearly explained in terms of the supporting fundamental physics.The present work proposes an elastic closed form solution to estimate fracture initiation demand when the hydraulic fracturing is interacting concurrent to a cave back. This analytical model was able to explain the reduced demand of breakdown pressure due to the modified stress field near a cave back (near field stress). In addition to this result, there are preliminary implications for cave engineering applications to support cases of cave induction but also new potential applications for directional caving as conceptualised in the present work. This development is part of a current ongoing research that will also consider aspects related to fracture propagation.

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Rock Preconditioning Application in Virgin Caving Condition in a Panel Caving Mine, CODELCO Chile El Teniente Division

Cited by 9 publications

References 0 publications

Evaluation of intensive preconditioning in block and panel caving – part II, quantifying the effect on seismicity and draw rates

Evaluation of intensive preconditioning in block and panel caving – part II, quantifying the effect on seismicity and draw rates

Geotechnical analysis of blasting sequence and resulting shapes of drawbells in block cave mines

Modelling of fracture initiation near a cave back and its implications for hydraulic fracturing concurrent to cave mining

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