The Masonry Method Of High Alumina Refractory Bricks And Clay Refractory Bricks For Blast Furnace Bottom

The masonry method of high alumina refractory bricks and clay refractory bricks for blast furnace bottom



The clay bricks and high alumina refractory bricks used for blast furnace bottom are generally composed of several vertical brick layers (with a layer height of 345mm or 400mm), each layer is laid in a cross shape, and some are also laid in a straight shape. The centerlines of adjacent brick layers are offset by 30 degrees from each other. The centerline of the upper layer furnace bottom brick forms a 30 ° -60 ° angle with the centerline of the tapping hole.

Centerline of bricklaying for blast furnace bottom

1. Centerline of the iron outlet; 2- Odd layer centerline; 3- Double layer centerline

(1) There are generally two ways to build the cross shape at the center of the furnace bottom:

Schematic diagram of cross shaped bricklaying at the center of the furnace bottom

A-brick type is 400mm × 150mm × 90mm; b-brick type is 345mm × 150mm × 75mm

1) During masonry, according to the cross centerline drawn on the cooling wall, four guide square blocks with flat outer surfaces and at right angles to each other should be accurately placed along the line as the basis for the cross shaped masonry center. In order to avoid gaps between the center points of the upper and lower brick layers, when drawing the center line of the upper brick, the center point should be offset by half the thickness of the brick from the center point of the base brick.

2) Based on the centerline of the furnace bottom cross, first locate the center brick by drawing straight cross lines in equal directions on the brick surface of the center brick, so that they coincide with the furnace bottom cross line. Then, offset the thickness of the brick row by half, re draw the cross line, and set 4 guide square blocks along the line as the guide surface for masonry.

1- Brick type; 2- Guided square timber; 3- Centerline
Because square wood has both guiding and supporting effects, both one side and the bottom of its supporting brick need to be polished and form a right angle with each other. It is necessary to use a level or ruler to check the straightness of the square wood along the line, and the error should not exceed 0.1mm. When laying the bottom of each layer of bricks, use a fine sight ruler to check whether the two straight cross lines are at a right angle to each other. The guiding square wood and the drawn cross line must be strictly consistent and not skewed. Otherwise, the diagonal masonry of the central cross shaped brick row will result in extensive processing of the entire brick layer, affecting the quality of masonry.

The cross line at the center of the furnace bottom is the key to the entire layer of furnace bottom masonry. After laying the bottom, the brick joints and straightness should be checked to see if they meet the requirements. If the quality meets the rules, then the two diagonal bricks should be laid in sequence next to the listed bricks. After laying 3-4 rows of bricks and adding stability to the masonry, the guide square timber should be removed. Then all four corners can be bricked simultaneously.

The high alumina brick refractory brick and clay brick furnace bottom should be constructed with phosphate slurry. During masonry, the thickness of the brick joints should be strictly controlled according to the construction specifications and rules; It is necessary to fill the mud in the joints of masonry bricks; The viscosity of the mud should be strictly controlled.

① The procedure for bricklaying is: first, dry the bricks, check the joints, and move the bricks in sequence to one side; Next, clean the work surface, lay a layer of mud, and perform brushing, dipping, and kneading actions as shown in Figure 4. Due to the fast flow of phosphate slurry, in order to avoid "lower blockage", it is often operated with both hands. One hand holds the lower end of the brick, and the other hand presses against the lower part of the intersection between the large surface and the side of the brick. After rubbing up and down 4-5 times, the brick is placed in place.

② The key operations for laying furnace bottom bricks are: stable adhesion, low leaning, short pulling, and heavy kneading.

Stable adhesion: Coat both the large and small surfaces of the brick with mud, and do not take it out immediately.

Low leaning: When leaning a brick that has been coated with mortar against a already laid brick, it should be lowered as much as possible. This can allow most of the mud on the brick surface to enter the brick joints, achieving the goal of filling the mortar joints.

Short pull and heavy kneading: It means that the distance of pulling up and down during kneading should be short (usually 30-40mm), and the kneading action should be heavy and tight. After the bricks are in place, it is not advisable to strike them too hard with a wooden hammer, otherwise it will cause the mud to sink and loosen.

The operation sequence of bricklaying at the bottom of the furnace

Operation sequence for laying high alumina refractory bricks and clay bricks at the bottom of the furnace

A - Staining with slurry; B-end of slurry sticking; C - Take out the brick; D - Prepare to turn around; The e-turn has ended; F-Rubbing masonry

The straightness error of each brick at the bottom of the furnace shall not exceed 2mm. Excessive errors will cause "lower blockage" in the masonry. During construction, after each row of bricks is laid, a level ruler is used to measure the straightness error of the bricks in the masonry. In addition, the flatness of the surface of the furnace bottom brick layer should be checked, and the gaps should be checked with a ruler and a feeler gauge. Then measure the relative elevation difference of each point in the scene. Grind and level the locally raised areas with an angular grinder to facilitate the construction of the base furnace bottom bricks. There should be a 100-150mm expansion joint between the furnace bottom masonry and the cooling wall (or the protective wall of the carbon block), filled with carbon material, with a compression ratio of not less than 40%. To avoid extensive processing of bricks, carbon material is used to fill any areas at the edges that are less than half the width of the brick.