Current Efficiency for Zinc Refining & Extraction

Theme: Smelting and Power

Expected Pilot Duration - 3 Months

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Challenge Summary

DSC Zinc uses electrolytic cells to refine & extract Zinc. Currently, against an average daily target of 715 MT of Zinc at 200 KA, only 694 MT is produced. A comprehensive predictive model is needed to simulate, analyze and optimize to improve the production efficiency.

Challenge Scenario

At DSC-Zinc, Concentrate (ZnS) received from different mines is roasted into Calcine (ZnO). Then Calcine is leached in the form of ZnSo4 solution using the spent received from Cellhouse. Leached ZnSo4 solution is further processed in Purification to reduce all impurities to the acceptable range (Zn=145 g/l; Ca <0.042 ppm; Co<0.12 ppm; Cu<0.20 ppm; Sb<0.001 ppm; Fe<2 ppm; Ni<0.2 ppm).

In the Cellhouse, electrowinning process is used to deposit the Zinc on an Aluminum cathode from the ZnSo4 solution received from Purification by passing a DC of 200 KA in cells for deposition of Zinc on the cathode. At 200 kA, the desired cathode production at 93% CE (Current Efficiency) is 715 MT, but the actual output is only 694 MT at 90% CE leading to a direct loss of Zinc by 20 MT daily. Loss of CE is having a direct impact on cathode production and Cost of Production (COP) for DSC-Zinc. The output efficiency depends on a large variety of factors, including but not limited to cathode efficiency, purity of ZnSO4, cell healthiness and acidity in spent etc. A solution to simulate, analyze and optimize the output production and current efficiency that considers all the factors affecting production is needed.

Profile of the end users

DSC Zinc-Cellhouse team

Able to see the real time purity of supply solution, Able to see the efficiency improvement on day-to-day basis

DSC L&P Team

Able to see the quality of calcine received from Roaster, Able to see the purity of solution being supplied to Cellhouse

Solution Requirements

Track the utilization of current & calculate current efficiency

Maintain alignment of electrodes

Monitor efficiency & healthiness of cells

Stripping of cathodes from cells & maintaining anode washing quality

Optimize leaching of calcine received from Roaster

Measurement of impurity level in solution to acceptable range as supplied to Cellhouse

Measure/quantify the composition supply to the cellhouse as per requirement

Analytical predictive model for simulation & analysis that extensively takes into consideration the following factors to optimize production efficiency:

Variables impacting current efficiency: Supply solution quality, Anode washing quality, cell cleaning quality, current leakages, Zinc, and acidity in spent.

Impurity level in supply solution: - Co, Cd, Fe, Ni, Cu, Sb, Ge, Sb, Tl

Current leakages: - Leakages through coolers, cell bottom insulators and bus bar

Cell healthiness: - Electrode healthiness, low level of mud in cell etc.

Cell wise efficiency - Mark Cells having low efficiency

Cell temp.- Temp of individual cells

Cathode quality must not deteriorate.

Cell Voltages must not increase as it will directly affect rating (MT/MW) which have a direct impact on COP of the plant.

Expected Outcomes

1. Quantified Metrics & Outcomes:
Operational KPIs/Metrics Current Value Expected Target Value
Current Efficiency 90% 93%
Zinc Cathode Production 695 MT/Day 715 MT/Day

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