The document discusses various aspects of filtration and drying processes used in mineral processing. It describes how filtration separates solids from liquids using a porous medium, and identifies some key factors that affect filtration like pressure difference, pore size, and filter cake thickness. It also outlines different types of filters like pressure filters, suction filters, and cake filters. The document then covers common drying methods like rotary dryers, and whether heating is done directly or indirectly. The overall content provides an overview of solid-liquid separation and moisture removal techniques for mineral processing applications.

1. PRESENTED TO:
ENGR. NADEEM AHMAD
PRESENTED BY:
Gulfam Hussain

2. Filtration is the process of separating
solids from liquid by means of porous
medium which retains the solid but
allows the liquid to pass.

3.  The simplest type of filter
consists of a tube of small
bore through which the fluid
is sucked while the solid
particles accumulate at the
entrance.
 As the device is operated,
solids at first pass through
the tube, but they quickly
arch or bridge across the
opening, allowing only clear
liquid to pass

4.  The filtering area.
 The difference in pressure between two sides of
the filter.
 The average cross section of the pores within
the filter cake.
 The number of pores per unit area of the
septum.
 The thickness of the filter cake.

5.  Pressure type: pressure is applied to push the
liquid through the filter bed. Fluids flow through a
filter due to a difference in pressure fluid flows
from the high pressure side to the low pressure
side of the filter, leaving some material behind.
 The liquid may flow through the filter by the
force exerted by a pump.
 Suction type: suction is applied to pull the liquid
through the filter bed. It is a chemistry laboratory
technique which allows for a greater rate of
filtration.
 (used in chemical laboratories, for mineral
dressing in which interest centers on the cake)

7. Cake filters:
 Cake filters are the type most frequently used
in mineral processing, where the recovery of
large amounts of solids from fairly
concentrated slurries is the main requirement.
 Those where the main requirement is the
removal of small amounts of solid from
relatively dilute suspensions are known as
screening or clarification filters.

8. cake

9. Advantage:
 higher fluid capacity per square foot of
filtering surface,
 better control of cake formation,
 possibility of better washing of cake.
Disadvantage:
 A great disadvantage is that they are
intermittent (stopping and starting at regular
intervals) instead of continuous.

10. DRYING.
 The drying of is the last operation
performed in the mineral processing
plant.
 It reduces the cost of transport and is
usually aimed at reducing the moisture
content to about 5% by weight.
 Dust losses are often a problem if the
moisture content is lower.

11. Rotary thermal dryers:
 Rotary thermal dryers are often used.
 These consist of a relatively long cylindrical
shell mounted on rollers.
 Driven at a speed of up to 25 rev/min.
 The shell is at a slight slope, so that material
moves from the feed to discharge end under
gravity.
 Hot gases, or air, are fed in either at the feed
end to give parallel flow or at the discharge
to give counter-current flow.

12.  Direct fired, parallel flow rotary dryer.

13. Methods of heating or drying:
Direct Method:
 The method in which the hot gases pass
through the material in the dryer.
 The direct-fired is the dryer most commonly
used in the minerals industry.
Indirect Method:
 The method in which the material is in an
inner shell, heated externally by hot gases.
 The indirect-fired type being used when the
material must not contact the hot combustion
gases.

14.  The product from the dryers is often
stockpiled, before being loaded on to trucks
or rail-cars as required for shipment.
 The containers may be closed, or the surface
of the contents sprayed with a skin-forming
solution, in order to eliminate dust losses.