The one constant in mineral processing is variability. This is especially true when it comes to the operation of thickeners, which must adapt to ever-changing conditions in the ore slurry to deliver a clear overflow and thickened underflow. Managing flocculant dosage remains the gold standard for efficient solid-liquid separation, yet it presents a number of challenges. Mineral processors with simple, constant-feed systems may attempt to manage flocculant levels by controlling pump speed, but this approach is often inadequate. What’s required is an advanced control system that can accommodate fluctuations in ore type and feed rates to change flocculant dose in real time, maximizing throughput and production.
Solenis’ Alcotech™ TC Automation Technology provides a reliable, low-cost, and fully automated platform to control how much flocculant is added to thickeners and clarifiers used in mineral processing. Because particle properties affect the degree of separation that can be achieved with sedimentation, the Alcotech TC unit is purpose-built to respond to changes in size, shape, surface chemistry, and solids density. It can also respond to variations in thickener influent flow rate, pH, and flocculant dilution rate. By precisely controlling flocculation and solids inventory, the Alcotech TC Automation Technology stabilizes and optimizes the entire thickening process, leading to several key benefits:
- Consistent solids settling velocity
- Consistent underflow density
- Prevention of solids carryover in the overflow stream
- Optimized flocculant addition
- Reduced chemical costs
Dynamic, Flexible Flocculant Control
Alcotech TC Automation Technology works by measuring the settling rate in thickeners. It does this by pulling a slurry sample from the feedwell and drawing it into a measuring chamber. Next, a sensor measures the height of the solid-liquid interface at specific time intervals and calculates the settling rate based on these high and low points. Finally, a proprietary control algorithm determines how much flocculant is required based on the settling rate, solids input, and processing rate.
Two different sensor technologies are available based on customer needs:
Alcotech Ultra — Uses an ultrasonic sensor to measure settling rate, making it an ideal technology when slurry samples are cloudy or when there is a lot of color in the liquor.
Alcotech Wedgewood — Uses a photoelectric cell to optically measure both settling rate and clarity, making it possible to control both the addition of flocculant and coagulant.
Both systems come with acid wash variations to keep units clean in environments where certain minerals (iron, for example) can stain equipment. And they can be configured with a dual measuring chamber for use in high-aeration conditions where foam must be removed before an accurate measurement can take place.
The Alcotech units can measure and control flocculant pumps directly, or they can send signals back to a customer’s DCS for additional calculations involving data from other systems. Additionally, it can share data with the Solenis™ Cloud to allow for 24/7 access to real-time data.
Proven Technology
Engineers originally developed the Alcotech TC Automation Technology for use with customers in the nickel laterite processing industry. It has since been used in a wide range of mineral processing applications, including gold, copper, uranium, coal, and mineral sands production. Today, it has delivered proven performance in more than 500 installations spanning a 30-year history.
More Information
If you would like to learn more about the Alcotech TC Automation Technology, talk to a Solenis expert today.
