MBBR Mine Effluent Treatment Plant

Mandate and Objectives

ASDR was mandated to design a mining effluent treatment plant to treat several contaminants prior to discharge to the environment. The plant was also designed with the required flexibility to adapt to other possible contaminants that may appear following start-up of operations, including the need to treat ammoniacal nitrogen.

Plant Criteria and Specifications

• Nominal and maximum flow rates of 1,200 m3/h and 1,800 m3/h, respectively;
• Very strict discharge criteria for a wide range of contaminants;
• Treatment of WAD cyanides by oxidation (INCO process);
• Treatment of metals (Al, Cu, Fe, Ni, Zn) by precipitation (hydroxides and sulphides);
• Solid-liquid separation by a linear decanter and automated sludge extraction; Nitrate treatment (Moving Bed Biofilm Reactor (MBBR));
• Dewatering and sludge management with geosynthetic bags.

Engineering

ASDR was responsible for the engineering of the water treatment plant, from defining design criteria to issuing plans for construction. The design of the treatment plant also included laboratory tests and the preparation of all the technical specifications for all equipment.

• Laboratory treatability tests;
• Assessment of design criteria;
• Process flowsheet design and sizing;
• Pre-feasibility and feasibility engineering;
• Detailed engineering: civil (structure and hydraulics), mechanical, electrical, instrumentation and control;
• Validation of equipment selection;
• Coordination with the construction contractor.

Procurement

• Preparation of equipment technical specifications;
• Discussion with equipment suppliers during the purchasing period;
• Recommendations following analysis of the proposals received.

Plant Start-Up and Operation

• Start-up of the treatment plant and development of the various procedures and documents necessary for the operation of the system;
• Project management to accommodate the processing of molybdenum and ammoniacal nitrogen. These projects allowed the plant the required flexibility to handle these new contaminants;
• Supervision of operations over a period of 18 months;

Summary

The flowsheet developed by ASDR along with contingency processing for new contaminants allowed the company a quick plant start-up and the ability to meet discharge compliance for a wide variety of water contaminants. Since the plant’s start-up, ASDR has provided consulting services and advice for the continuous optimization of the mine’s operations.