Author 1:
Name & Surname: Kalugin A. I.
Company: Apatit JSC (Kirovsk, Russia)
Work Position: Technical Director—Principal Engineer
Scientific Degree: Candidate of Engineering Sciences
Contacts: e-mail: AKalugin@phosagro.ru

Author 2:
Name & Surname: Gumenichenko K. M.
Company: Apatit JSC (Kirovsk, Russia)
Work Position: Chief of Apatite–Nepheline Processing Plant-3

Author 3:
Name & Surname: Barabash A. Yu.
Company: Apatit JSC (Kirovsk, Russia)
Work Position: Head of Production and Technical Service, Apatite–Nepheline Processing Plant-3

Author 4:
Name & Surname: Arsentiev S. S.
Company: Apatit JSC (Kirovsk, Russia)
Work Position: Head of Technical Support Service, Apatite–Nepheline Processing Plant-3

In 2005 Apatit JSC trialed a screen manufactured by Derrick (model Stack Sizer 2SG48-60W-1STK) with a variable frequency drive on a semicommercial plant. The semicommercial and commercial trials demonstrated efficiency of the fine screening technology used in the ball milling circuit of ore preparation for flotation. The commercial operation revealed the increase in the milling output owing to reduced circulating load, increased coarseness of flotation feed and sufficient dissociation of apatite. From the mineralogical analysis, the amount of intergrown pieces of apatite and other minerals is substantially lower in the large size categories of the under-screen than in the same size categories of the cyclone discharge. As the result, +0.16 mm size content of the flotation concentrate is increased from 13–15% to ~30%. According to the grain-size composition, the apatite concentrate produced using the fine screening is close to the apatite concentrate grade Super (RF Technical Specifications 2111-37-00203938-96). The introduction of the fine screening and re-adjustment of the apatite-nepheline ore milling circuit towards maximum possible grain size with keeping the dissociation ability of intergrown pieces of minerals has ensured the optimized feed of ball mills MSHTS 55006500 with up to 400–420 t/h of ROM ore and improved the apatite concentrate production.

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