Estimating Weak Rock Strength
Factors Controlling the Strength of Weak Rock Masses: For the purposes of this paper a weak rock mass is defined as any rock mass in which the effective shear strength parameters are less than: effective cohesion, c’ = 25 psi (0.2 Mpa) effective friction angle, ∅’ = 30° using the Mohr Coulomb failure criticism. This would […]
Protection against Rockfall by Steel Wire Rope Safety Net Systems
Wire Rope Net Rockfall Barriers A rockfall protection system with the appropriate strength characteristics and height can be designed. Wire rope net rockfall protection barriers of varying designs have been engineered with the proven ability to withstand impact kinetic energies ranging from 81 kJ (30 ft-tons) for the simplest of designs, to a maximum of […]
Ore Grade Control
Initial ore grade control was based on blast hole samples collected in two stages by an “automatic” sample collection device (sometimes called a rocket sampler). A sample was collected for the top 3 m (10 ft) in a holes and then the bag was changed so that a sample was collected for the lower 3 […]
Mining Truck Dispatching Method
The main purpose of truck dispatching systems is to increase equipment productivity. Since productivity is measured in tonnage or volume over time, productivity increases are made by decreasing truck and shovel cycle time. This decrease can be translated into more production with the existing operating equipment or constant production with a smaller equipment fleet. Concurrent […]
Tailings Backfill
This report presents a study of three typical tailings samples as potential cemented backfill in underground mines. The testing series was unique in that the pulp densities of the samples were all above 75 pct solids. Test results included dry density; slump; percent settling after 28 days of curing; tensile strength after 28, 120, and […]
Water-Jet Rock Drilling
Abstract The U.S. Bureau of Mines has patented and transferred to industry an abrasive-enhanced water-jet rock drill. This drill incorporates three novel components: a collimator, jet deflectors for cutting clearance, and an unpressurized swivel, which rotates at 1,000 rpm while passing 20 gpm of an abrasive slurry flowing at 1,000 ft/s. Drilling occurs through the […]
Ore Cutoff Grade Optimisation
We will discuss the fundamental elements of cutoff grade optimization and demonstrate how cutoff grade optimization may improve NPV of a given operation under different scenarios. The first case study is a description of cutoff grade optimization for a gold deposit to be mined in a single push-back with a small mill capacity. The second […]
Water Jet Assisted Rock Cutting
High-volume, low-pressure water jets have been employed for erosion of loosely consolidated rocks for centuries. This excavation method finds application in specialized circumstances even today. The use of high-pressure, low-volume water jets for rock cutting is more recent and was made possible by the development of high-pressure water pumps. Despite the benefits often claimed for […]
Ultimate Pit Limit Design
In open pit mine planning, the design of the most profitable ultimate pit limit is a prerequisite to developing a feasible mining sequence. Presently, the design of an ultimate pit is achieved through a computer program in most of the mining companies. 3-D block model is commonly applied to represent geologic and economic information of […]
Placer Gold Prospecting Equipment
The outfit to be taken on a prospecting trip depends upon the mode of transportation, the work contemplated, and the funds available. Enough equipment should be taken, but unnecessary articles make extra work. When a more or less permanent camp is established, added equipment for personal comfort and efficiency can be obtained. Usually a cabin […]