Chromite Refractory Brick Production

The steps for production of chromite refractory brick are as follow:

(1) size reduction

(2) coarse, fine and powder preparation

(3) weighing and mixing

(4) forming

(5) drying

(6) firing

Firstly, the chromite ores are crushed with an impact crusher and crushed raw materials are screened. Required raw materials such as coarse grain of 4 kg, fine grain of 4 kg and powder of 4 kg are weighed. Proper amount of binder is added to make mud material to form the brick. In this process, magnesium chloride with clean water (300 ml) is used as chemical binder. The material is mixed and kneaded for 10 minutes after adding the binder to obtain homogeneous mud material. The total weight of the brick was 11.3 kg. To produce chromite refractory brick, pressed under a press of 400 tons, dried and fired at 1580°C for fifty two hours. The dimensions and shape of chromite refractory brick are shown Table 1.and Figure 1, respectively.

TABLE I DIMENSIONS OF REFRACTORY BRICK

The standard properties such as apparent porosity, apparent specific gravity, bulk density and water absorption that the chromite brick should possess were measured.

A sample was cut off to a size of approximately 100×100×50 mm and dried in a dryer at 105-120°C till constant weight was obtained. It was weighed with a balance and taken as W1.

(1) Sample
(2) Beaker
(3) Vacuum Desiccator
(4) Cover of Desiccator
(5) Contact Portion of Desiccator
(6) Pressure Resistant Cover Rubber
(7) Cock of Manometer
(8) Scale of Manometer
(9) Vacuum Pump
(10) Cock for Oil Pouring
(11) Oil (Kerosene)
(12) Cock
(13) Exhausting Port

The test piece was put in the vacuum desiccator, and covered. On the contact surface of the desiccator cover grease was applied for air tightness. As shown in Fig.2, the cock of oil pouring was closed and the cock of manometer was opened and then the operation of the vacuum pump was started.

After that, suction for 15 minutes under the vacuum of 2.0 KPa (15mmHg) or under, the cock of manometer was closed and the oil was injected by opening the cock of oil pouring until the sample was soaked completely.

Then, the cock of oil pouring was closed and the cock of manometer was opened. The vacuum pump was turned off and the cock was opened to introduce the air gradually. Then, the desiccator was returned to the atmospheric pressure. After 30 minutes under the atmospheric pressure, the samples are left from the oil.