Mining Rule of Thumb

The primary usage of Rules of Thumb should be in the development of conceptual designs and feasibility studies or, when a quick decision is required in the solution of an operating problem. Although an approximated answer, derived from a Rule of Thumb may solve an immediate problem, Rules of Thumb are not a substitute for the application of sound engineering and design methodologies. Although we firmly believe that the presented Rules of Thumb provide great continuing value to our industry, McIntosh Engineering does not guarantee their validity, nor do we (or the referenced individual sources) accept responsibility for application of the Rules of Thumb by others. Where possible, direct quotes have been provided from individual references; however, it is possible that referenced sources may not have directly stated the Rule of Thumb for which they are assigned credit. Although we have endeavored to accurately quote all individual references contained in the Rules of Thumb compilation, we apologize in advance for any misquotes that may be attributed to individual sources. We will provide updates to the Rules of Thumb compilation, as we become aware of corrections that may be necessary.

Field: Cost Estimating

Area: Budget Estimates

• An allowance (such as 15%) should be specifically determined and added to the contractor's formal bid price for a mining project to account for contract clauses relating to unavoidable extra work, delays, ground conditions, over-break, grouting, de-watering, claims, and other unforeseen items. Jack de la Vergne

Area: Cost of Estimating

• A detailed estimate for routine, repetitive work (i.e. a long drive on a mine level) may cost as little as 0.5% of the project cost. On the other hand, it may cost up to 5% to adequately estimate projects involving specialized work, such as underground construction and equipment installation. Various

Area: Cost of Feasibility Study

• The cost of a detailed feasibility study will be in a range from 0.5% to 1.5% of the total estimated project cost. Frohling and Lewis
• The cost of a detailed or "bankable" feasibility study is typically in the range of 2% to 5% of the project, if the costs of additional (in-fill) drilling, assaying, metallurgical testing, geotechnical investigations, etc. are added to the direct and indirect costs of the study itself. R. S. Frew

Area: Engineering, Procurement, and Construction Management

• The Engineering, Procurement, and Construction Management (EPCM) cost will be approximately 17% for surface and underground construction and 5% for underground development. Jack de la Vergne

Area: Haulage

• The economical tramming distance for a 5 cubic yard capacity LHD is 500 feet and will produce 500 tons per shift, for an 8-yard LHD, it is 800 feet and 800 tons per shift. Sandy Watson
• Haulage costs for open pit are at least 40% of the total mining costs; therefore, proximity of the waste dumps to the rim of the pit is of great importance. Frank Kaeschager

Area: Miscellaneous

• The installed cost of a long conveyorway is approximately equal to the cost of driving the drift or decline in which it is to be placed. Jack de la Vergne
• In a trackless mine operating around the clock, there should be 0.8 journeyman mechanic or electrician on the payroll for each major unit of mobile equipment in the underground fleet. John Gilbert
• On average, for each cubic yard of concrete measured from the neat lines on drawings, approximately 110 Lbs. of reinforcing steel and 12 square feet of forms will be required. Jack de la Vergne
• The overall advance rate of a trackless heading may be increased by 30% and the unit cost decreased by 15% when two headings become available. Bruce Lang
• The cost to slash a trackless heading wider while it is being advanced is 80% of the cost of the heading itself, on a volumetric basis. Bruce Lang

Area: Overbreak

• The amount of over-break to be estimated against rock for a concrete pour will average approximately one foot in every applicable direction, more at brows, lips, and in bad ground. Jack de la Vergne
• On average, for each one cubic yard of concrete measured from the neat lines on drawings, there will be two cubic yards required underground, due to over-break and waste. Jack de la Vergne