Tailings are an ever-present problem on the global mining market. A case study in Brazil shows the potential of filter presses with the latest control system becoming a gamechanger in handling this issue.
Itaminas is a Brazilian iron ore extraction company founded in 1959 and is one of the first mining companies in Brazil to decommission dams associated with the production of iron ore concentrate. Looking for an alternative to dispose of its tailings, the company decided on the implementation of a filtering system and subsequent stacking of dry tailings, and on ANDRITZ Separation as their partner in this task. Four ANDRITZ overhead filter presses manufactured locally in Brazil in the largest size of 2500 x 2500 mm were chosen as the ideal equipment. Tests showed that a membrane pressurisation system with water is the best way of achieving the geotechnical moisture content in the cake required for dry disposal.
Figure 1: One of the filter presses in operation at Itaminas.
The filter presses are now consistently achieving a moisture content of around 17%, while the performance tests produced a cake density of 2.5 t/m3 and delivered final performance that was 34% higher than expected. The recovery of 2200 m3 of clean water per filter press from the filtration process helps avoid plant outages during the dry season. After full implementation of the project, 10500 tpd of dry substance will be produced.
To tailor the presses for the specific needs of Itaminas, they were equipped with double-openings, a double-washer, a second feed port and a package of mixed membrane/chamber plates that can be easily accessed from the side. The real stand-out feature of the filter presses, however, is their automation system.
The intelligent ANDRITZ filter press.
How intelligent filtration equipment is cutting the costs of tailings treatment
As tailings treatment is not a process step that turns a profit, it should be handled as cost-efficiently as possible. In the case of Itaminas, this is achieved by equipping the filter presses with a Metris addIQ Prime control system. Metris addIQ control systems are part of Metris, the ANDRITZ brand for digital solutions, and are one of the most innovative automation solutions on the market today.
The control system chosen by Itaminas combines state-of-the-art hardware with high-end trending and diagnostic functions, maximising the performance of the filter presses. With a 12 in. panel touchscreen as standard, its design allows intuitive operation, crossing barriers of language or training. Combined with Metris addIQ Connect, it provides the resources for remote monitoring in the future, also enabling remote support for fast interaction between the on-site machine and the ANDRITZ specialists.
How ANDRITZ filter presses ensure efficient filtration even under roughest conditions.
Metris addIQ Connect enables use of the filter press app for Windows, Android, and iOS (smartphones, tablets, and PCs), one of the most interesting features for the tailings treatment process. With this app, the operator is able to directly access process live data as well as machine-related documentation. Furthermore, the control system collects and stores the performance data of the filter press for later analysis, be this to further improve performance or to enable predictive maintenance. Different KPIs are shown in one step on the filter press radar screen, giving a quick overview when any intervention is needed. Combined with an automatic e-mail notifier for the most critical process alarms, the operator can take action immediately if values differ from the norm. Additionally, automatic reports are generated (every shift, every day, every month) that include process values and the corresponding trend curves, and these can also be forwarded to an e-mail recipient.
Figure 2: Filter press app to visualise key process parameters in real time.
Intelligent filter presses go one step further, including even more beneficial features: Consistent automated monitoring of the shifting plate angle is another advantage of intelligent filter presses. When small amounts of cake remain on the plates, they become more and more misaligned after every discharge – intelligent sensors are able to detect the angle changes and inform the operator when the ideal time would be to start a washing cycle, making the machine less operator-reliant. Another standout feature that is simple, yet clever, is the plate package divider. This detail enables a noteworthy increase in the speed of cake discharge, enabling discharge times as short as 0.5 - 1 sec/plate and, therefore, increasing capacity.
Small features such as this are what enables the intelligent filter press to raise tailings dewatering to a new level and take a huge leap towards potentially autonomous machine operation in the future.
Stackable, safe, sustainable: The smart approach to tailings.
International technology group ANDRITZ offers a broad portfolio of innovative plants, equipment, systems and services for the pulp and paper industry, the hydropower sector, the metals processing and forming industry, pumps, solid/liquid separation in the municipal and industrial sectors, as well as animal feed and biomass pelleting. Plants for power generation, flue gas cleaning, recycling and the production of nonwovens and panelboard complete the global product and service offering. Innovative products and services in the industrial digitalisation sector are offered under the brand name Metris and help customers to make their plants more user-friendly, efficient and profitable. The publicly listed group has around 26 950 employees and more than 280 locations in over 40 countries.
ANDRITZ Separation provides mechanical and thermal technologies as well as services and the related automation solutions for solid/liquid separation, serving the chemical, environmental, food, mining and minerals industries. The customised, innovative solutions focus on minimising the use of resources and achieving highest process efficiency, thus making a substantial contribution towards sustainable environmental protection. For more information, visit www.andritz.com/separation.
Read the article online at: https://www.globalminingreview.com/special-reports/06072021/enhanced-efficiency-in-tailings-treatment-with-intelligent-process-control/