1908 ] 
Monazite and Monazite Mining 
77 
gravels are washed into shaking hoppers and then through sluice 
boxes, the over size thrown out and the sands fed to Wilfley 
tables. At one mine it is necessary to raise the gravels by a 
mechanical elevator in order to bring them to a sufficient height 
to feed them to the table. They are fed into a revolving screen 
and from that to the table. The heads from this first washing do 
not contain a very large per cent of the monazite, and the mid- 
dlings are, therefore, re-fed to the table with other feed ore. In 
some cases the feed ore is all run over the machine and a rough 
concentrate first obtained and then this re-fed. The product from 
these machines contain from 50 to 80 and occasionally 90 per cent 
of monazite. Where there is a large amount of the heavy black 
sands occurring in the gravel with the monazite, it is almost 
impossible to get the percentage much over 50 per cent monazite. 
Where, however, these occur more sparingly, it is possible by this 
method to obtain a monazite concentrate containing 80 per cent 
monazite. 
All the concentrates from the sluice boxes and Wilfley tables 
have to be dried before they can be treated on the magnetic sepa- 
rators. There are two different methods used in the monazite dis- 
trict for this purpose. In one the sand is spread over an oiled or 
rubber cloth in a thin layer and exposed to the heat of the sun. 
It dries very quickly, due perhaps partly to the heat absorbed by 
the dark iron sand. It requires, however, a considerable surface 
to accommodate any large amount of sand. The other method of 
drying is by heating over furnaces. A small ditch from 4 to 8 
feet long and 1^ to 2 feet wide and about one foot deep is dug, at 
one end of which there is built a rock or brick chimney. The 
ditch is usually built up of stones with an opening at the opposite 
end of the chimney for firing. Over the ditch there is a sheet iron 
cover or drying plate. The monazite is spread on this and exposed 
to the action of the hot fire underneath. These dry sands are 
often further concentrated by means of the ordinary horseshoe 
magnet, which picks out all the magnetite. The miners are paid 
for their sand on the basis of 100 per cent product and the nearer 
they can bring their sand to this, the better prices they receive for 
