An on-stream analyzer and small regrind cyclones (their small 1/2 Apexes) were being plugged by trash coming from the underground mine in the form of wood and plastic. A simple solution was to install a homemade screen box on the cyclone overflow prior to feeding flotation. The operator cleans it daily, thanks to the overhead crane.
Separate and remove debris from your valuable feed. Our Trash Screen options allow you to filter your wet media with confidence. Effective and easy to install and maintain, the Trash Screen offers improved throughput and productivity, while being durable enough to significantly cut down on maintenance and repair costs.
When it comes to your raw feed materials, only a small fraction of the overall slurry is worth extracting. The rest is a mixture of trash and debris that you need to be able to separate out before you can get your end product. However, that process separating and removing the trash from the treasure is extremely high wear, and the toll it takes on equipment can lead to costly and frequent maintenance, repairs and downtime. That said, with the right solution you can enjoy effective trash separation without the hassle. All it takes is a reliable Trash Screen.
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Hello, I work in a gold processing plant where we have a vibrating trash screen in our milling circuit made from a polywedge material. We have a considerable amount of thin scales forming on the screens which are removed every shut down with Sulphamic acid. Recently, the scale formation has increased drastically with increase in width as well. can anyone help me with some reasons why these scales are forming? is there a particular chemical that can cause scale formation on the trash screen?
In addition to xrf, that will give the total chemical composition, a quick look under a simple stereo microscope will reveal if the scale is a single substance or a combination. Also it may be worth checking the hardness of your plant water, past and present.
If it is being removed by sulphamic acid in all probability it is CaCO3 scale which is very common in this area in gold plants. Lime added for pH control often contributes to the scale formation but usually the hardness of the water is a major contributing factor. If it is water hardness there is a likelihood that scale is also forming in the water reticulation system around the plant as well. Anti-scalent additions can reduce or control these build-ups. The suppliers of these reagents will often identify scales and potential for water to form scale. Scale formation on the screen is difficult to control because of the agitation and exposure to air that occurs during the screening process. Whilst acid washing will remove some of the scale often a mechanical means such as high pressure water blasting is also used to physically remove the scale providing a quick way of cleaning the screen. Eventually though the screens need to be replaced. With acid washing particularly in-situ there is a risk of HCN gas formation during this.
You will spend time and money doing sampling and your issue will plague you forever, the Caco3 is not presumably affecting the process but rather its build up has manifested itself but a significant decrease in screening open area
Stewart has asked all the right questions! changing the screen media to a flexi type rubber may retain the open area. This has been my experience drain and rinse applications in coal wash plants. The soft rubber moves and this prevents the buildup on the screens. Not sure about the application but would help in any way i could.
At our "concrete recycling facility" we had expensive time consuming build-up on our fines screens between the jaw and cone. We replaced wire mesh screens with spring steel parallel wire screens (brand unknown but I can find out). The spring steel screens at 3X the cost have been priceless for productivity, had 0 failures since installation and come highly recommended for this issue. In my opinion they should be a #1 solution for well water or hard water issues. Build up on structural members has not yet become an issue in our application.
I did a bit of poking around and I wonder if you are using that sort of screen layout, cause if you are - there is absolutely no surprise that you are having issues, that will not work - its way to rigid , you are getting oversize passing through the gaps that are pried open by scaling.
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Rock passes into a dump hopper and is then transferred to a vibrating grizzly screen. The oversized material is sent to a jaw crusher. The crushed product is combined with the grizzly undersize and the ore is conveyed to the coarse ore bin.
Coarse ore is ground, sized, slurried with pregnant liquor, and pumped to the hydrocyclone cluster. Oversized material from the hydrocyclone cluster underflow is returned to the ball mill for further grinding. The hydrocyclone overflow is sent to a trash screen which rejects oversized material and debris.
The trash screen underflow slurry is fed to the high rate pre-leach thickener. Diluted flocculant and barren solution are added to the feed of the thickener to assist in solids settling and thickening. Thickener underflow is pumped to the leaching circuit. Overflow pregnant solution containing precious metals dissolved into solution is pumped to the clarifier.
Cyanide solution is added to leach the gold from the slurry using a series of mixed leach tanks. Oxygen is injected into first leach tank using a recirculation pump to maintain sufficient dissolved oxygen in the slurry for leaching. Slaked lime slurry is used to increase pulp pH levels.
The countercurrent decantation (CCD) circuit recovers precious metals leached into solution using a multistage countercurrent thickener. Slurry from the leaching process reports to the first CCD thickener. The thickened underflow is pumped to the next CCD thickener where it is washed with recovered solution from the previous CCD thickener. Thickened underflow slurry from the final CCD thickener is pumped to the tailings paste thickener. The wash solution will flow countercurrent to the solids flow, increasing in precious metal concentration as it proceeds to the first CCD thickener. The pregnant solution from the first CCD thickener is pumped to the buoyant media clarifier.
A buoyant media clarifier provides initial clarification of the solution. Clarifier overflow is pumped to the polishing filter circuit. The remaining suspended solids in the clarified solution are removed by pressure leaf filters. Diatomaceous earth is used to precoat the filters and as a body feed. Filtered pregnant solution is discharged to the vacuum deaeration column which removes oxygen from the solution in a packed tower.
Final recovery of the precious metals is accomplished by filtering the solution using filter presses. The recessed plate-type filter press collects the filter cake between the filter plates in the chambers formed by the recessed plates. At the end of the filtration cycle, the free liquid is displaced from the filter cake by an air blow step. The filter press is opened and the cake falls from between the plates. It is then collected and sent to the smelter.
For over a hundred years, miners have used dilute alkaline cyanide solutions (e.g., sodium cyanide [NaCN] around pH 10-11) to leach (dissolve) gold and other precious metals, from their ores. The gold is usually in the form of small flakes mixed with other minerals. It is difficult to separate mechanically, so it is dissolved and then recovered by other means.
Carbon-in-leach process adds the leaching agent (cyanide solution) and activated carbon together into the slurry of ore and water. This prevents other carbonaceous materials (wood, clay, etc.) in the ores from adsorbing the gold first (preg-robbing).
Slurry leaves the final adsorption stage through a linear screen, which catches any residual carbon fragments. These are recycled.A carbon sizing, linear screen ejects the carbon fines from the adsorption circuit.A settling tank (e.g., AltaFlo Thickener) or filter collects carbon fines, and reclaims water.*But if the silver content in the ore is high, see CCD Merrill-Crowe Gold Silver flow sheet.There are three subsets of the carbon adsorption approach:Carbon-in-Pulp Most efficient for slurries. Process leaches the gold first, adds carbon separately.Carbon-in-Leach Effective for carbonaceous ore slurries. Process adds leaching agent and carbon together, keeping preg-robbing material (like wood) from adsorbing the gold.Carbon-in-Column For non-slurries, solution-only. Typical for heap leach applications.Leaching detention time is dependent on:Particle Size Finer particles dissolve quicker, less time needed Dissolved Oxygen Rate of dissolution is directly proportional to amount of oxygen present.
Located near Cloncurry in northwest Queensland, Australia, the Lorena gold project was acquired by Malachite Resources in 2010. Malachite operates the mine through its wholly owned subsidiary Volga Elderberry (VEPL).
The Queensland Department of Environment and Heritage Protection granted the environmental authority (EA) permit for the project in May 2014. The project has the potential to extend its mine life with the development of an underground operation beneath open-cut operation.
Mining works commenced in October 2017, while the processing plant was also commissioned in the same year. Ore processing at Lorena commenced in February 2018, and first gold was poured at the end of March 2018.
Located approximately 15km to the east of Cloncurry, the project is hosted within the mining lease ML7147, which is one of the six mining leases held by Malachite Resources. The company also holds two exploration permits (EPM18189 and EPM18908) in the region.
Gold mineralisation at Lorena is hosted within a south-west steeply dipping fault system comprising silicified and brecciated shale and siltstone of the Toole Creek volcanic formation. The mineralisation is classified as massive and occurs in conjunction with stringer sulphide type and copper-gold mineralisation.
The mineralisation is developed within steeply south-dipping shear zones, up to 12m-wide striking east-west and northwest-southeast within the license area. The zones host sedimentary units, breccias and fault gouge with quartz-carbonate-sulphide pods.
Malachite Resources entered a 50/50 joint venture agreement with BCD Resources (supported by MKS Switzerland) in July 2013 for the first stage development of the gold mine and to construct a 120,000t capacity concentrate plant for treating the produced ore.
Malachite reached an agreement with Ore Processing Services (OPS) in March 2016 for developing and operating a modular mineral processing plant to treat the ore produced at Lorena. Malachite also reached a partnership and funding arrangement with OPS and Cloncurry Gold Recovery Management (CGR) for the development of the project.
Malachite will hold a 55% joint venture interest in the project, while CGR and OPS will hold 30% and 15% respectively, as part of the agreement. Chinova Resources holds a 70% stake in CGR, while private mining and contracting company BIM Gold holds the remaining 30%.
OPS reached an agreement in September 2016 to acquire the stake of MKS Precious Metals (Australia) in the concentrate plant developed by BCD at Lorena site. The company constructed the 200,000 tonnes per annum (tpa) Lorena concentrate plant as well as supplied a modular carbon-in-leach (CIL) circuit following the agreement.
Conventional open-pit mining method, including drilling and blasting to remove waste rock, is applied in the first stage of Lorena mine. An estimated 250,000t of ore is proposed to be mined from the open-cut operation.
Run-of-mine (ROM) ore passes through a two-stage crushing process, using a jaw crusher and a cone crusher, before passing through the milling circuit. The circuit operates at 20 tonnes per hour (tph) and comprises a grinding mill operating in a closed circuit.
Slurry from the grinding circuit will be directed to the flotation circuit through a trash screen. At the flotation circuit, the material passes through roughing, scavenging and cleaning processes. The concentrate then passes through to the magnetic separation circuit, where the pyrrhotite is removed by using LIMS drum magnetic separators.