Mini blast furnace

About Mini Blast Furnace A Mini Blast Furnace (commonly known as Mandir Bhatti or Shahi Bhatti) is a simple, time-tested and widely used system to produce secondary lead in India and many other countries. It is the most basic of all furnaces and a production system based on this technology has certain distinct characteristics such as: Low Project Capital Cost Low Energy Cost ( wooden coke fired) Easy to install Easy to operate & maintain Production of low Antimony Lead (soft lead) at low temperature Generates high pollution Description of Mini Blast Furnace The Furnace itself is a modified blast furnace which consists of a brick lined structure with fire brick oven in the midst and a metal Exo skeletal structure outside. Raw material & fuel (coke) is charged manually through the side metal doors fitted in the brick structure and air is provided from the FD fans provided at the back of the brick structure. Molten metal & slag is tapped at the pits made in front of the brick structure and flue gases are sucked from the top of the brick structure which is provided with a metallic hood. A typical Double Oven Mini Blast Furnace has the following standard sizes & specifications: Outside Dimensions of Brick Structure 2400mm L x 1900mm W x 2400mm H No. of Ovens 2 Nos. Oven Size Top Dia 600mm Bottom Dia 250mm Depth 650mm No. of FD Fans 2 Nos. (1 for each oven) FD Fan Capacity 300cmh at 250mm of WG No. of Charging Doors 2 Nos. (1 for each oven) Charging Door Dimensions 1100mm H x 650mm W Manufacturing Process Lead to be manufactured from Mini Blast Furnace is usually obtained from scrapped batteries. They are cut open or broken to segregate lead scrap, plastic and other materials from it. Lead scrap in the form of lead powder and plates etc. is charged in the furnace along with a proportionate charge of wooden coke. Thereafter the furnace is manually fired with the help of rags. FD Fan provides the necessary air required for combustion from the back of the furnace. Coke in the oven performs the functions of both, the fuel as well as a reducing agent for obtaining lead from its oxides charged in the form of lead plates & powder. Temperature of the furnace is maintained at the desired level for approximately 30 minutes, after which molten lead along with slag flows out from the bottom of the oven into the outlet pit. Here slag is separated and molten lead is poured into Ingot Moulds. To maintain this, continuous charge of raw material and coke is maintained in the furnace. This process leads to generation of flue gases which are toxic in nature and need appropriate and adequate Air Pollution Control System for their treatment. Process Details for a typical Double Mini Blast Furnace Raw Material Charged 700-800 kg hr. Fuel used Wooden Coke Calorific Value of Fuel used 4000-5000 kCal kg Fuel Consumed 70-75 kg hr. Air provided for process 300 cmh Lead Produced (1st Charge) 300-350 kg hr. Flue Gas generation 8000-9000 cmh Advantages and Disadvantages of Mini Blast Furnace Advantages No consumables used other than Wooden Coke which is also used as Fuel Low Power Consumption Produces low Antimony Lead suitable for soft lead purposes Pollution can be controlled with minimum fugitive emissions Easy to install, operate & maintain Disadvantages Cannot recover 100% lead in the first operation Subsequent recovery of lead after first recovery consumes higher coke & manpower. Equipment cannot be scaled up for higher production capacities. Various types of lead present in used batteries, plates and paste of lead oxide are charged in the furnace. In addition to these, certain compounds of sulphur are also present in the batteries. When this material is heated in the presence of carbon, lead oxide is converted to lead. This conversion along with burning of fuel generates flue gases and fumes containing dust, dirt, oxides of lead, lead particles and other impurities etc. Hence, to meet various goals of maintaining employees' health, for factory environments as well as regulatory requirements, it becomes imperative to get high end Air Pollution Control Systems to be installed with the Mini Blast Furnaces. At the time of Delivery