FILTRATION & THICKENING
these challenging operational conditions .
Furthermore , FLSmidth has received an additional order for two AFP2500 filter presses for Torex Gold ' s mining operations situated in Guerrero , Mexico . Torex Gold has already embraced dry stack tailings at its mine site , with seven filters currently in operation . With a new mine in development and the need for plant expansion , FLSmidth secured a contract for the supply of two AFP2500 filter presses , each equipped with 124 chambers and each capable of dewatering approximately 8,500 t / d of tailings . FLSmidth says it is thrilled to collaborate with both of these clients , and the five filters are presently in the manufacturing phase , scheduled for delivery in early 2024 . FLSmidth told IM it is also currently pursuing multiple other large scale filtration projects , with a high level of customer engagement and interest in the optimised AFP2500 filter design .
Matec - a complete filtration solution for CSN
One of the oldest iron ore mining operations in Brazil , Companhia Siderúrgica Nacional ( CSN ) - owned Casa de Pedra holds more than 6 billion tons of resources and 3 billion tons in reserves . The operation mines four orebodies with the iron ore sent for processing in the Central Plant ( wet route ) or the Mobile Plants ( dry route ), located near the extraction areas .
Casa de Pedra currently has a production capacity of 30 Mt / y . Products resulting from the beneficiation process are grain , sinter feed and pellet feed . The ore is transported to the Port of Itaguaí ( TECAR ) via rail terminals located in Casa de Pedra and the Pires Complex .
Opting to decommission its upstream wet tailings dam several years ago , CSN began the design and construction of an extensive new dry stacked tailings plant with Massa , Italyheadquartered Matec Industries in the early parts of 2018 , breaking the complete installation into three phases .
Phase 1 ( solid feed 550 t / h in design , with 585 t / h achieved ) comprises two vertical high rake thickeners and four Magnum 2000 / 190PLT TT2 Fast Filter Presses fed straight from CSN ’ s tailings dam and was successfully commissioned towards the end of 2018 . The plant footprint is 62 m by 15 m and each filter press having 190 plates . The filter cake is removed by conveyor and stockpiled by a radial conveyor . Phase 2 ( solids feed 650 t / h ) then eliminated the feed to the upstream tailings dam entirely whilst still rehabilitating the tailings dam . That plant comprises of three vertical high rake thickeners and five Magnum 2000 / 190PLT TT2 Fast Filter Presses . Again each filter press has 190 plates . Filter cake is removed with conveyors and stockpiled by a radial conveyor . Phase 3 which was commissioned in 2022 comprises another two Magnum 2000 / 190PLT TT2 Fast Filter Presses as well as a 40 m horizontal thickener . Overall the tailings plant with all three phases installed now has a capacity of 35,000 t / d .
On the wider market , Matec points out that high pressure filter presses are used widely today in tailings management operations and their implementation was a huge turning point in the market . “ They are particularly suitable for applications with a high presence of ultrafines and possible presence of clay ... the high pressure technology presents a lower capital cost and operational cost when comparing to low pressure filter presses that make use of membrane squeeze features , delivering the highest water recovery ratio .”
It adds : " Tailings dewatering applications require very large throughputs and with the use of high pressure technology the size of the filter press can be optimised making the high pressure filter press economical for large-scale filtration applications . In theory the higher the feed pressure , without sacrificing volumetric flow rate , the higher the volumetric throughput of dry stackable material to safely store tailings and reduce the risks , particularly over the long term .”
Innovations in Matec filter presses include the patented TT2 Fast System , developed to solve the problem of sludge discharging opening and closing dead time in filter presses . Thanks to this system that reduces also the length of the machine , the process of plate discharging has decreased from the usual 15 / 20 min to 3 min for 150 plates . This system guarantees also a 30 % increase in productivity and a reduction in operating and maintenance electrical costs , in addition to an easier use of the machine . The TT2 works by opening the main cylinder just once ,
One of the filter press installations at CSN in Brazil supplied by Matec
then it closes , in order to open the first 10 plates . The quick opening of the plates is used to open 10 plates at a time through the back and forth shifting . The two oleodynamic cylinders are installed on lateral bars and provided with mechanical modules . The opening of the two cylinders works at high speed through the oleodynamic power unit .
The Air Gasser ® Automatic Shaker is a pneumatic system to guarantee the detachment of the filtering cloth panels created with a series of high efficiency pneumatic cylinders . They lift a stainless steel bar by means of special pivots and then release the plate in order to give it a suitable vertical stress . The Matec shaker it says does not wear out and guarantees an efficient vertical shaking of the plate and the complete detachment of the mud cake .
The Core Blow system is designed to clean the feed hole , at the end of the filtration process , of residual sludge collected in the diffusion duct through the plates . The filter press is equipped with an air duct inside the moving plate to blow the residual sludge out of the plates at the end of the filtration process . A suitable valve system allows the blown sludge to bypass the pump and be discharged back into the collection tank .
The Tilt Sensor system consists of upper and lower proximity sensors that control the tilt of the last closing plate . In the software that manages the filter press , the delay time between the two sensors can be set . If the second sensor is activated within the set time after the first , the machine can continue its cycle normally . If not , an alarm will be triggered .
Matec filter presses can also be equipped with
10 International Mining | OCTOBER 2023