According to the terms and conditions of the contract, Maerz will supply engineering, license, know-how, material and equipment and provide technical assistance services.
It supplies heat for the process and also acts as a reducing agent. The major quality requirements of the non-coking coal are i non-coking characteristics, ii low ash content, iii low sulphur content, iv good reactivity, v high ash fusion temperature, and vi medium volatile matter.
Non-coking character of the coal is necessary since the coking reaction leads to formation of rings inside the kiln. Practically permissible caking index limit for the rotary kiln process is 3 maximum.
Low ash content of the coal is necessary since Rotary kiln high ash leads to under-utilization of the kiln volume available for reduction. It also increases the consumption of fixed carbon since additional energy is consumed in heating the inert ash mass to reaction temperature.
Low sulphur content is required to control the sulphur in the DRI. The sulphur in the coal is to be 0.
Good reactivity of the coal is needed since an important step in solid state reduction process is the forward reaction, whereby carbon dioxide generated from Rotary kiln of coal reacts with coal to regenerate carbon monoxide Boudouard reaction. Hence, the coal is to possess sufficient reactivity so that the Boudouard reaction proceeds at the desired rate.
Bituminous and sub-bituminous coals show usually good reactivity suitable for production of DRI. Ash fusion temperature is another important characteristic.
Coals having low ash fusion temperature leads to sticky mass resulting into unstable kiln operation due to the formation of the accretions inside the kiln which reduces the reduction rate by formation of slag layer on surface of the ore.
Hence coals with ash fusion temperature higher than deg C are desirable for rotary kiln operation. Volatile matter of the coal is to be optimum for coal based rotary kiln process. Coal with very low volatile matter result in very low reactivity of char, and thus give rise to poor metallized product.
Very high volatile coals, though yield highly reactive char, are also not preferred since it increases gas volume in the kiln.
Coals for direct reduction in the rotary kiln need to have low swelling index. Normally swelling index is to be less than 1. The physical and chemical specifications of the non-coking coal are as follows.
Size of lumps — 5 mm to 20 mm Size of fines — less than 5 mm Contamination shale, stones etc. Typical specification of the dolomite is given below.
The cross section of the rotary kiln is at Fig 1. Fig 1 Cross section of rotary kiln Coal based direct reduction process is based on the solid reducing agent which is non-coking coal. The reaction takes place at high temp deg C to deg C.
Coal plays a dual role in the kiln. Part of coal is used as fuel to supply the desired heat so as to take the raw materials to the desired temperature. But main role of coal is to supply carbon for the reduction process. Dolomite is used as sulphur scavenger which finally comes out with the char.
Char contains ash of coal and other impurities of iron ore. The reactions inside the kiln take place in several stages during the reduction of iron ore to DRI. Iron ore undergoes the following final reduction reaction. However, the reduction from oxide to metal does not take place in one step, but by gradual removal of oxygen giving, rise to various intermediate oxides.Refractory, or the lining utilized on the interior of rotary kilns, is a critical component in ensuring process efficiency and prolonging the life of a rotary grupobittia.com, we’ll discuss everything you need to know about refractory, including how it works, the different types, and best practices for preventative care.
Every dryer or kiln has different needs depending on past use and operating conditions. At Rotary Kiln and Dryer we offer a number of services that can help you get the most out of your rotary unit.
Sludge Lime Disposal Project.
Sludge lime disposal project in Yanjiao sewage plant Yanjiao sewage treatment plant is located in the southwest of Yanjiao Development Zone. Rotary Kiln Services - Hot Kiln Alignment - On site tyre, roller and thrust roller surface machining and grinding while the kiln is in operation at up to 3,5 rpm.
Rotary EQUIPMENT. Specialists “Serving the rock and asphalt industries since ” © Evans & Daniels Inc. rotary - Traduzione del vocabolo e dei suoi composti, e discussioni del forum.