Table of Contents
Flotation was practiced by this and succeeding engineers to concentrate many of the non-metallic minerals available from Canadian resources. Experimentation, and some extensive experimentation. A number are still under investigation. A few have evolved into producing plants. The results obtained for some have been used to increase efficiencies in existing plants. Results for others have been applied in comprehensive pilot plant operations.
The Flotability Program
The overall intent of this program is to assist in the solution of non-metallic flotation problems by pointing out possible areas for effecting separations. Considering the number of non-metallic minerals and the number of potential collectors it is a program which could be extended indefinitely. There is also a factor of change. Several reagents employed at the beginning of the program in 1959 are no longer produced. The provision of surfactants which can be broken down by natural forces, i.e. “biodegradable” after their primary function is fulfilled is becoming unescapable to manufacturers.
Results are reported as excellent, good, fair, or poor flotation and arranged according to class and type of collector. Known flotation systems for various minerals are usually confirmed and new areas for possible flotation are indicated. The new areas do not always prove successful under unit-cell conditions, but most do.
Flotation of Barite and Celestite
During the past few years considerable interest has been shown in the concentration of barite and celestite. Since 1967, requests to seek beneficiation methods for barite from five locations and celestite from two locations, have been received. One of these ores was composed of barite, fluorite, and calcite, with small amounts of quartz, celestite, and hematite. Another was chiefly celestite, quartz and calcite, with minor hematite, barite, and silicates.
Pilot plant operations conducted by another organization, applying the method to this ore, have produced up to 92% recovery of a 97.8% BaSO4 product. It should be noted that the small celestite content concentrates with the barite. It normally amounts to less than 3% in concentrate.
Concentration of Spodumene
About three years ago a request was received to produce a spodumene concentrate containing above 6.0% Li2O and less than 0.05% Fe2O3 from a feed with approximately 2.0% Li2O and 0.1% Fe2O3. Feldspar and quartz comprised the bulk of this ore. Minor minerals were mainly silicates.
Spodumene concentration processes developed by the Industrial Minerals Milling Section in the mid-50’s had employed reverse flotation with some success. Similar experiments applied to the above ore were successful in producing products with above 6% Li2O but tended to leave the iron with the spodumene. Direct spodumene flotation with fatty acids also tended to float the iron. Although magnetic separation proved effective in reducing the Fe2O3 in product, it was decided to see if something more could be done by flotation alone.
Among other aspects examined by unit-cell experimentation was a comparison between oleic acid, an amine employed extensively in earlier work (ARMAC T), and Armeen L-9. The advantage of L-9 for the rejection of iron was demonstrated.
The use of Armeen L-9 was carefully explored by means of unit-cell experiments until a preferred method had been evolved. In performing these experiments, the fines, decanted after initial grind, were not separately floated. It was observed from this work that in addition to the 55% recovery of Li2O in product, additional recovery may be obtained from middlings (approximately 5.5%) and from floating the fines (approximately 10%) for a total potential recovery of around 70%. The composite product so derived remains close to 6% Li2O, usually slightly above.
Reagents
The highly competitive field of surfactant production results both in the availability of thousands of compounds at any one time and in a rapid variation of what is available. Many commodities have been on the market for decades while many others are introduced yearly, some of which prove durable while others disappear. In the past few years, long-established commodities are disappearing under the impact of demand for biodegradables.
In order to achieve some semblance of currency with the surfactant market as it applies to non-metallic flotation the Industrial Minerals Milling Section attempts to maintain contact with about 85 chemical manufacturing firms. Samples of approximately 500 reagents are kept on hand. Records are maintained by means of a Kardex system. Name, supplier, date of receipt, price, etc., appear on the card. The color of the card indicates acceptable shelf life, which may be six months, a year, two years, or indefinite. A form letter to the manufacturer or his representative requests renewal. Liaison is maintained with as many manufacturer’s representatives as possible.
