314 BROWN & HERON: GEOLOGY AND ORE DEPOSITS OF TAV^Y 



second rock breaker of the same type as the first, and thence directly 

 to a pair of rolls vertically below. The undersize with its water 

 passes under the rolls, taking their product to No. 2 trommel, which 

 has perforations of 6 mm. This trommel is over another pair 

 of rolls which treat its oversize. The undersize is again swept 

 with the product of the rolls to the 3rd trommel, which has holes 

 of 1 mm. At this point recovery begins. The oversize from No. 15 

 trommel falls into the supply launder of the first jig while the under- 

 size is taken into the 4th trommel which has holes of 2 mm. From 

 this final trommel the oversize passes to No. 2 (fine) jig and the 

 undersize to three hydraulic classifiers. It is intended that each 

 of the classifiers shall deliver a spigot product to each of three 

 " Record " tables, while the overflow is to go on to two Frue vanners. 

 The mill is not in final working order and the steps in the flow sheet 

 as outlined are subject to modification. 



The Pagaye and Widnes mills are both fitted with rolls, jigs and 

 tables and have been referred to in the descriptive section of this 

 report. 



Mr. G. N. Marks' proposals.— Mr. G. N. Marks has designed a 

 flow sheet suitable for Tavoy ores, in which the wolfram and cassi- 

 terite are not evenly distributed through the vein quartz, but are 

 patchy and coarse and often in large lumps. He is of the opinion, 

 which the writers share, that fine stamping or grinding with its attend- 

 ant loss in float is to be avoided. This means crushing the ore 

 as coarse as possible, classifying and recrushing in stages, and avoid- 

 ing a further crushing of the minerals by separating them out as 

 soon as possible. Rich ore which comes from scattered pockets 

 in the veins must be eliminated before it reaches the mill, and the 

 latter will then be fed with a low grade product. Under such 

 circumstances the smallest unit of any value would have a capacity 

 of 2,000 tons per month. The introduction of a travelling belt 

 or picking table, between the ore bin and the mill, is advocated, 

 to pick out waste and to collect the coarse wolfram and cassiterite 

 which form such a high percentage of the total ore contents. From 

 the picking belt, after passing over a grizzly which will allow say 

 two inch cubes to pass, the ore would be fed to No. 1 crusher, 

 preferably of the eccentric jaw type. The product would then go 

 to No. 2 crusher of the same sort, and be broken to about one inch 

 cubes and less, and then fed on to a picking belt to eliminate a 

 certain portion of mineral without further treatment. The crushed 



