Information Series 075
The Peace River iron deposits are situated in the Clear Hills district of northern Alberta, about 300 miles northwest of Edmonton. The deposits are close to all-weather roads and lie within 35 to 45 miles of railway facilities at Hines Creek.
The deposits consist of flat-lying oolitic sandstone 5 to 30 feet thick, exposed along the southeastern slopes of the Clear Hills. The iron content of the bed grades between 32 and 35 percent Fe, mainly in the form of goethite (Fe203. H2O). Resources have been estimated at 1, 124 million tons of which 227 million tons are considered 'proved' and 897 million tons are classed as 'probable or 'possible' resources. On the basis of grade and volume, the deposits constitute the largest potential source of iron ore in the four western provinces.
The composition of the deposits presents some problems to beneficiation and smelting by conventional techniques. The major impurity is silica (Si02), present both as discrete quartz grains and as an intergranular cement (opal). Also, the phosphurus content of the deposits is high, although alumina and sulfur contents are relatively low. Consequently, the ore must be beneficiated to increase the iron and lower the silica contents prior to smelting in a blast furnace or electric arc furnace.
A number of attempts have been made to upgrade or extract the iron content of the Peace River ore using magnetic separation, flotation, direct reduction, and acid leaching techniques. Large scale direct reduction tests carried out by the R-N Corporation at Birmingham, Alabama, in 1960, resulted in production of metallic briquette grading 90 percent Fe, which is suitable for conversion in an electric furnace; but the economic feasibility of this and similar beneficiation techniques is uncertain.
More recent work indicates that an alternative procedure for upgrading the ore involves mild reductive roasting followed by crushing and grinding to yield a magnetic concentrate. The grade of the concentrate, which ranges between 50 and 60 percent Fe, depends upon the degree of iron recovery; it appears to be most efficient at a level of about 3.5 parts iron to 1 part gauge.
The value of such a concentrate depends upon a number of factors including fuel and conversion costs, but available data suggest that it is approximately one-half the cost of a high-grade concentrate grading 10 parts iron to one part gangue. This value is estimated to be $11.50/ton in Edmonton and compares favourably with the cost of producing pelletized concentrate at the mine site, estimated to be between $9.95 and $14.80/ton for large-and small-scale operations, respectively. (Figures based on 1972 costs).
The availability of low cost, high quality coke favours direct reduction of the ore concentrate (in the form of self-fluxing sinter or pellets) in an electric furnace, or if a large market is available, smelting in a blast furnace. If coke costs are high compared to the costs of other energy sources (subbituminous coal or natural gas), then reproduction of the concentrate followed by conversion in an electric furnace may be the preferred smelting procedure.
Additional research is being carried out to determine the most efficient procedures for beneficiating the Peace River ore, and to characterize the properties of the ore concentrate and the iron produced from the concentrate.
Bertram, E.F. and Mellon, G.B. (1975): Peace River iron deposits; Alberta Research Council, ARC/AGS Information Series 75, 28 p.