MINERAL SEPARATION
Bunting has redesigned and refurbished the industrial magnetiser at its Redditch manufacturing facility in the UK , making it the largest DC impulse industrial magnetiser in the UK , outside of academia
magnet assemblies are built in an uncharged state and then placed within the magnetiser for charging to create a focused and specific shape of magnetic field . The nature of this created magnetic field dictates how the magnetic separator will separate ferrous metals and magnetically susceptible materials from nonmetallic materials as in the mining sector .
Bunting ’ s operations team continually review manufacturing processes for improvement opportunities and highlighted key benefits of upgrading the industrial magnetiser . These included significant operating efficiency improvements , which would support the continued sales growth .
The Redditch impulse industrial magnetiser is rated at 50 kW , drawing a continuous amount of DC current from the mains power . Each energising phase lasts for only 10 seconds and generates approximately 500 kJ of energy . The 12 t magnetiser stands 1.5-m tall on a 3 x 2-m footprint .
Since the upgrade , magnetisation of a magnet assembly requires significantly less ‘ magnetic hits ’, reducing the energy consumed by the magnetiser by over 30 %, Bunting explains . The quicker magnetising process results in freeing production resource , accommodating the extra demand created through sales growth . The size scope of chargeable magnet assemblies has also increased up to 2,000 x 1,400 x 400 mm , weighing approximately 5 t .
Adrian Coleman , Bunting ’ s European Engineering Manager , said : “ Magnetising is a key
stage within our manufacturing process and with the magnetiser refurbishment we are able to magnetise quicker and more efficiently than previously . The result is increased manufacturing capability and the ability to magnetise larger magnet assemblies .”
Eriez highlights magnetic developments
Jose Marin , Eriez ® Director of Minerals and Materials Processing , is of the opinion that the demand for higher purity industrial minerals will lead many mining companies down the road of investing in their magnetic separation processes .
The use of trunnion magnets for new and retrofit applications is one area he sees catching on , with these solutions installed at the discharge of a ball mill . Their main objective in this context is to remove ball chips and worn-out balls from the milling circuit .
“ It is a simple concept that requires a short stainless-steel barrel and a permanent magnet around it covering an arc length of about 200 ° on uni-directional mills ,” Marin explained . “ Trunnion magnets can be used on most ore , except for ferromagnetic ores such as magnetite or monoclinic pyrrhotite .”
A trunnion magnet is important to a milling circuit , Marin explains , as the magnetic removal of worn-out balls and chips ( scats ) ensures they exit in an upstream part of the circuit , as
opposed to being milled into a fine metallic powder and eventually making it to the concentrators ( flotation , gravity or magnetic ).
The trunnion magnet manufactured by Eriez has undergone a series of improvements in recent years , including a new wash water manifold to better wash the ore off the chips , the fitting of a 6 in ( 152 mm ) extension at the end of the barrel to help properly seal the discharge of the mill and the ability for the top section of the magnetic arc to pivot open – effectively reducing the disassembly time during barrel maintenance .
Wet drum magnets are also extensively used in mining , used in countless applications that require a solid design for metallurgical and mechanical performance – such as iron ore concentration or recovery of magnetite in heavy media circuits .
“ Even though significant improvements on wet drums took place during the 1990s and early 2000s , we continue to see additional improvement in reliability and more advanced features ,” Marin says .
Eriez developed a hybrid magnetic element with one objective in mind : improve iron recovery in the rougher stage of magnetite concentration . Comparative tests performed at an iron ore plant proved iron recovery performance , Marin says . The comparison was conducted on self-leveling CDA wet drum separators that are 48-in diameter by 125-in wide with a 1,000 gauss interpole magnetic element versus the hybrid element .
The Eriez Dry Vibrating Magnetic Filter is used for processing very dry fine industrial minerals and materials requiring an extremely high level of purity , such as lithium , Jose Marin says
70 International Mining | APRIL 2024