Abstract: Inflatable envelope systems for use with slurry products in back filling and other operations involving subterranean works. An envelope is inflated to partially crush deformable means disposed between the envelope and the wall of an excavation chamber so as to conform to the wall profile and oppose the flow of solidifiable material between the envelope and the wall.

Abstract: This invention pertains to inflatable envelope apparatus or pressurized container structures and associated methods to be used together with slurry products of concentrated or metallurgical plants in backfilling and other operations involving subterranean works. The pressurized container structures are envelopes which can be fabricated of various materials and shapes, or other light weight pressurized containers, the shape or volume of which is sustained by internal gas pressure. The technique for extracting a metal bearing substance comprises several steps, the principal ones being the placing within a subterranean chamber a pressurized envelope structure, pouring into the chamber adjacent the envelope structure slurry products emanating from a concentrator or flotation plant which lie in contact with but external to the pressurized envelope.