"The fluorspar-zinc orebody at Minerva No. 1 mine near Cave in Rock, in Hardin County, Illinois, would have been classed as non-commercial before the days of flotation milling and mine mechanization. The bulk of the ore requires fine grinding for acceptable beneficiation, and the assay of the head feed runs considerably lower than grades thought to be commercial in the fluorspar district prior to 1940.

However, the reserves found by drilling before the decision was made to invest in mine development, and the construction of a two-product, 250-ton, flotation mill, with complete power plant and surface shops, exceeded 600,000 tons. The belief that more than twice this tonnage of additional ore was very probable has been justified by subsequent prospecting. The shaft sinking commenced in 1942, and full plant operation commenced in 1944.

It was apparent from the beginning that full advantage of mine mechanization practices would have to be taken to keep mining costs as low as possible. The advantage of a large reserve opened the way for justifying the expenditure of capital for mechanical equipment costs of which could be depreciated over many tons and years. Selection of equipment types developed and used with some measure of success in other mining districts, having similar mining conditions, was based upon the need to lower unit mining costs per ton, within the limits imposed by milling capacity, 250 tons, later raised to 325 tons, per day.

This thesis describes the attempts to achieve the best applicable types of loading and hauling equipment to keep mining costs low in a mine where output is held down.

Other factors governing this trend toward utmost mechanization were (1) a desire to limit the size of the manpower requirements during a period of skilled mine labor shortage, (2) adopt equipment types of the operation of which could be taught to new employes, who lacked any mining experience, and (3) adopt equipment types which would help the mine achieve a better safety record than had been experienced in the fluorspar district"--Introduction, pages 2-3.


Forrester, James Donald, 1906-1979


Mining Engineering

Degree Name

Professional Degree in Mining Engineering


Missouri School of Mines and Metallurgy

Publication Date



v, 34 pages

Note about bibliography

Includes bibliographical references (page 31).

Geographic Coverage

Cave in Rock (Ill.)
Hardin County (Ill.)


© 1953 Robert Gill Montgomery, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Mining machinery
Loaders (Machines)
Fluorspar -- Illinois -- Hardin County

Thesis Number

T 1046

Print OCLC #


Electronic OCLC #



Thesis Location