A mixture of natural talc and borax is obtained via surface mining techniques an

Question

A mixture of natural talc and borax is obtained via surface mining techniques and is delivered in open-top trunks to the plant site. At the plant side it is crushed by large jaw crushers into pieces no larger than 10-15cm. The material then goes to a roller mill to further reduce the size. After passing through the roller mill, the material is screened; material smaller than 1 cm is stored for drying and larger material is recycled for further crushing.

The material that passes the screening step is conveyed to storage silos; from there is goes to alarge rotary kiln dryer where it is dried from 8% moisture to 0.2%. The moist solids feed rate to the dryer is 50,000 kg.hr. The rotary kiln is fired with a low sulfer fuel oil at a rate of 6.0 liters of fuel per 1000kg of feed.

The dried product is passed through an air contact cooler, and is then stored before shipment. The exhaust gases leave the dryer at 650 degrees F. The dusty gases exciting the dryer must be treated by approprate control equipment before being exhausted to the atmosphere.

For the more problems answered I can add more points to this question.

Any help on any or all of the problems will be very much appreciated. Thanks!

50,000 kg/hr. The rate of 6.0 liters of fuel per 1000 R 1000ough an ai b8ler, and is assed through an air contalt 88 exhaust gases leave the ty gases exiting the dryer must be treated h ried product is passed then stored before shipment. The 650°F. The dus ryer er at te control equipment before being exhausted to the atmosy aPp rocess flow schematic diagram is presented in Figure 9.1, y appro- here. A osphe A. priate control equipment before being e Figure 9.1 Process flow schematic diagram Raw material feed 1 Storage hopper Primary crusher 10-15 cm | Roller mill > 1 cm Screens s 1 cm Intermediate storage silo Rotary kiln dryer 2 Fuel oil Air exhaust 6 4 Air Cooler Product storage silo

Explanation / Answer

Material balance table :

1.)Dry solids : 52-4.17 = 47.83kg/hr

2.)Complete

3.)0.9*6000/1000*52*0.003 = 0.8424kg/hr

4.) Inlet air : wt % : N2 = 0.78*28/(0.78*28+0.21*32+0.01*40) = 0.754, O2 = 0.232, Ar = 0.014

Feed rate : N2 = 0.754*18*52= 705.744 kg/hr, O2 = 217.15200kg/hr. = 13.104 kg/hr

Total = 18*52 = 936 kg/hr

5.) Auxillary air = 0.3*50000 = 15000kg/hr

6.)2% of dry solids => 0.02*46 =0.92 kg/hr and division similar to Inlet air by wt. %.

a.) Fuel oil specific gravity = 0.9=> fuel oil rate = 6000 * 0.90 = 5.4 kg/1000kg of feed.

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