Neves Corvo Mine is a drift and fill operation that achieves tight filling using hydraulic backfill. This paper examines the backfill process from production on surface, through to placing it in stopes with quality control and monitoring of the final product. The constituents of the fill are described, as well as the characteristics required to provide general stability of the rock mass and a working platform. In addition, studies to improve the quality of the hydraulic backfill are described.
La Mine de Neves Corvo est une exploitation "drift and fill" ou le remblayage jusque au jusqu'au toit est obtenu par remblayage hydraulic. Cette etude porte sur le processus de remblayage depuis production en surface jusqu'a la mise en place dans les chambres avec un suivi de contrôle de qualite et verification du Produit final. Les composants du remlayage sont decrits, aussi que les caracteristiques necessairs à l'obtention d'une stabilite generale de la masse rocheuse et de la plateforme de travail. En outre des etudes pour amelliorer la qualite du remblayge hydraulique sont decrit dans cet article.
Die Stollen im Bergwerk Neves Corvo werden im sogenannten "Vorantreib- Anfuell-Verfahren" vorangetrieben, durch das eine kompakte Auffuelling mittels hydraulischen Anschuettung (Rueckfuellung) erreicht wird. Der vorliegende Text befasst sich mit dem Anschuettverfahren, vom Oberflachenabbau ueber Stollenvorantrieb bis hin zur Qualitatskontrolle und Üborwachung des Endprodukts. Es werden die einzelnen Elemente de Auffuellung beschrieben, sowie die geforderten Merkmale, um eine allgemeine Festigkeit der Gesteinsmasse und der Arbeitsbuehne zu gewahrleisten. In zusatzlichen Untersuchungen werden Massnahmen beschrieben, um die Qualitat der hydraulischen Anfuellung zu verbessern.
The Neves Corvo mine is located in southern Portugal on the western end of the Iberian Pyrite Belt. Neves Corvo is mining a polymetallic sulphide deposit with an annual production of 1.7 million tonnes of copper and tin ore. Production commenced in December 1988 from two of the five are bodies, Graça and Corvo. Both orebodies are shallow dipping, structurally complex, and contain a number of are types of varying grade, hence the drift and fill method of mining was chosen to ensure maximum recovery, minimum dilution, and high selectivity, figures 1 & 2. To date the Lower Graça zone has mined eight levels representing a total vertical height of 45m. In this zone the ore body has an average strike length of 200m and a width of 100m. The backfill placed in the drifts has both a primary and secondary role. The primary role is to provide regional stability by filling the void between the hanging and footwalls and provide a working platform for the levels above. To effectively serve this role the backfill must be capable of draining freely and have sufficient strength for trafficability. The secondary role is to prevent falls from the back and reduce loosening in the levels above, while minimizing dilution from sloughing of the fill. To effectively serve this role it must be tight against the back, have a high early strength and maintain self standing vertical walls for the height of the drift. An efficient response to the above needs is directly related to the uniaxial, and triaxial strength characteristics of the mixture.
The hydraulic backfill consists of 25% water (by mass), 3–5% tailings, 3–5% cement, with sand making up the remainder. This sand is fluvial and very silicious, fine (0–2mm), and uniformly graded. The cement is portland type II with fly ash. The tailings are cycloned and the underflow used in the fill.