Adopting Tailings Management System
The key to successful adoption of the system is in the ability to thicken
the tailings to a degree that, upon discharge, would allow them to flow to
a reasonable and predictable field deposition slope. Every mine produces tailings
that have a unique relation between concentration of solids and deposition
is the first parameter that must be obtained in order to establish the cost
of providing thickening capability that will achieve
the desired tailings
consistency. In spite of numerous attempts, it has not been possible to predict
the field deposition slope directly from variables such as grain size distribution,
particle specific surfaces, consistency, and pH.
The following is a list of our services:
- Laboratory Tests and Laboratory Report.
- Tailings deposition tests are carried out at the TMS laboratory in South River Ontario, to establish a graphical relation between percent solids of the
tailings and the anticipated field deposition slope angle. At times a relationship may be
obtained from proprietary tests carried out in a deposition trough into which
tailings are discharged at different percent solids, revealing corresponding
resultant slopes. The above tests together with attendant rheological properties provide information for establishing the
optimum degree of thickening for sizing of thickening and delivery equipment. To enable
disposal volume quantities to be estimated throughout the duration of the operation,
the progressively increasing bulk density of the future in-situ deposit is
obtained in a large-size special consolidation device. This same device permits
the determination of the corresponding hydraulic conductivity of the tailings for environmental
(seepage) considerations. The basic tests also include grain size determinations
to 0.002 mm, for reference and correlation purposes, and Atterberg limits,
if applicable, for geotechnical classification of the tailings. Finally, shrinkage
limit tests are to be carried out to establish the bulk density of the tailings
under the drying effect of the climate at the site. Shrinkage tests are particularly
significant for the well-drained sloped tailings deposits that are subjected
to natural drying conditions.
- For most projects, three or four 20-litre pails of tailings is sufficient sample to carry out all the above tests. The sample may be obtained from an existing operation or from a mineralogical testing laboratory for a proposed project.
- It is normal for suppliers of pumps and pipelines to do rheological testing. However, as noted above we regularly obtain preliminary rheological parameters for the high percent solids often required for a TMS. We find that the agreement between the rheology parameters and the deposition trough is good for fine grained tailings and deposition slopes between 1 to 3 percent.
- If the laboratory tests and an examination of the existing conditions (climatic
and topographic) indicate that conversion to the TMS would be beneficial,
practical and economical, a site visit by Dennis Netherton or project specific
senior associate is recommended to inspect site, discuss the TMS with the
operating staff, and to answer department specific questions.
- Study to Determine Optimal Disposal Capacity and Establish a Schedule for Discharge and Placement of Tailings
- An analysis is made of the topographic plans, site constraints, climatic conditions, and the schedule of anticipated tailings production. On the basis of this information, a site-specific study of tailings disposal is made in order to determine optimal site capacity. Volume storage determinations and slope angle studies are made for preparation of a schedule of Thickened Tailings discharge. Also included is a recommended generalized layout plan of the proposed scheme, discharge system, water recycle positioning, dam locations and heights, and reclamation recommendations. The degree and timetable for the progressive thickening required during the life of the project is indicated, if appropriate. Generally, it will be found that the Feasibility and Preliminary Design Reports are sufficiently detailed for the general consultant, client, or Prime Contractor to obtain cost estimates, and produce a final design details and Contract Documents. At the client's request and our recommendation, we are available for progress and development meetings as the project takes shape in the field.