Mineral Processing Pilot Plant Trials

Mineral Processing Pilot Plant Trials

Personnel from engineering firms frequently use data from pilot-plant operations for designing a full- scale plant. Data from pilot- plant testing may be supplied by the client, bv independent research laboratories, or. in other cases, by the engineering people involved in the pilot-plant operation to develop their own engineering, metallurgical, mineral processing and chemical data.

It is obvious that the information obtained from a small-scale operation can be no more accurate than the test work that is performed. As large expenditures may hinge on the results from a pilot plant, personnel assignments and monetary expenditures should be made to ensure that all required data is collected in a timely and accurate manner. Failure of a major installation that is based on inaccurate test data reflects no credit on the client or on the engineering firm involved.

When a small replica of a commercial plant is properly installed and operated, a wide range of essential information can be obtained, and the use of such pilot plants is common in many industries. This example will deal particularly with pilot plants used to develop techniques for the mineral dressing industry where such information can be obtained from a separate pilot plant, or. as in the case of many concentrators, a portion of the full-scale plant can be operated independently of the remainder of the plant and permit testing new processes, new techniques, or different reagents.

Many of the requirements for a reliable test installation are widely recognized as follows:

  • Ore for the pilot plant must be representative of that to be treated in such characteristics as size, grade, mineralogy, hardness, and moisture content.
  • Equipment must be properly proportioned in both size and number of units for the required treatment.
  • Water-supply systems, such as those for water reclamation and recirculation, must be similar to those proposed for the full-scale treatment.
  • All pilot-plant inputs, outputs, and process streams require weighing and sampling followed by accurate assaying of samples.

Deficiencies, of which the following are repre­sentative. can generally be found even in the most carefully planned pilot plants.

  • In an effort to avoid the use of too-small equipment units, attritioning is commonly performed In one cell, conditioning in one tank, and flotation cleaning in one or possibly two flotation cells. Because of pulp short-circuiting, such equipment errors will indicate the need for more than the correct amount of time for attritioning. conditioning, flotation, etc., and will result in erroneous recoveries.
  • Particularly when one section of an operating plant is used for test purposes, it is often inconvenient to arrange that it be equipped with its own return-water circuit, and water may be supplied from the general mill reclaimed-water system. Although such an arrangement is acceptable under some circumstances, in others it can give erroneous test results through failure to develop a proper build-up of detrimental impurities in the test-plant water circuit.
  • Unless special care is taken it often develops that insufficient provision has been made for accurate sampling of one or more of the test products. This may lead to the omission of some automatic samplers and the requirement that some products be hand-sampled by the pilot- plant operator at carefully specified and frequent intervals. This situation is loaded with dynamite. At those times when the plant is not operating at maximum measure all products to allow’ cross-checking of metallurgical results so that they can be accepted with complete confidence in their reliability.

In summary, a pilot plant must be designed and operated to satisfy two objectives. First, it must treat representative ore in a manner consistent with anticipated commercial operation, yielding all data required for feasibility and profitability studies, and final plant design. Second, the data from a pilot plant must be in sufficient detail to allow assessment of reliability and reproducibility.

The Circulating Load: Practical Mineral Processing Plant Design by an Old-Tie Ore Dresser