high volume high quality grinding
general comminution inc
‘High Efficiency Material Grinding Solutions for Industry & Research.
Coal Processing and Slurry Fuels

The Szego Mill excels in simultaneous grinding, beneficiation and production  of
coal-slurry fuels. A patent was granted for simultaneous grinding and beneficiation of
coal with oil and water in the Szego Mill. In the mill, ash is liberated from coal and
enters the water phase, and coal is reduced in size and forms agglomerates in the oil
phase. The oil phase is then separated from the water phase, resulting in a stable
coal slurry fuel.
Grinding performance (% above size) vs number
of passes for coal at 1300 kg/h in the SM320 mill
Reactivation of sorbent for capture of sulfur from coal combustion

Limestone is added to fluid bed coal burners to capture sulfur, producing
compounds which end up in the ash. The limestone becomes deactivated before all
of it is consumed due to reaction at the particle exterior. It can be reactivated with
grinding and hydration, and this can be done in one step using the Szego Mill, as
demonstrated in pilot scale work by Natural Resources Canada. Use of limestone for
sulfur capture was 18% lower, which represents a significant cost reduction.
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03102607 Advanced fluidized bed combustion sorbent
reactivation technology

Anthonv. E. J.
et al. Industrial & Engineering Chemistrv Research. 2003.
42, (6),1162-1173.

A new technique for simultaneous grinding and hydrating of fluidized
bed combustion (FBC) bottom ash was developed. This method was
effective in hydrating’the CaO component of’ the ash, so that the
sorbent is reactivated. Careful control of water levels is required to
prevent energy demand increases for grinding. No problems associated
with the potentially exothermic reaction of water with FBC bottom ash
were observed during grinding. When excess water (over that required
by hydration) is used, the resulting material is a slurry and, while
quantity conversion of CaO in the solids is achieved, using the slurry
for the sorbent would require a redesign of the limestone feed system.
Therefore, coal or unreacted ash is added to the mixture after grinding.
The resulting dry product contains the spent bed material in a
completely hydrated form. The reactivated ash produced was evaluated
for sulfur capture using thermogravimetric analysis, and a CFBC pilot
plant. Conversion rates of almost 100% are achieved for ash after
grinding hydration. An industrial demonstration of the technology has
supported its viability with no decrease in sulfur capture, while
limestone requirements decreased by 18%. The economic implications
of the industrial applicability of the technology are outlined in a case
study using the Point Aconi CFBC unit. Decreased limestone usage is
calculated to net savings in the order of $500000/year. The project is
calculated to have an equity payback of < 1 year.