Test of waste magnesia carbon brick becomes hot repair material for converter

Magnesia-carbon brick test

• Raw material

The main raw materials used in the test are waste magnesia-carbon brick particles (5~3, 3 ~1, and≤1mm), MS95 sintered magnesia fine powder (≤0.074mm), and modified asphalt (≤0.15mm, softening point 112.5 ℃, Coking value 58.2%) is the binder , Ⅰanthracene oil (density 1.04 ～ 1.15g · cm-3, coking value 0.56%) is the flux, the additives are B4C powder (≤0.045mm) and w (Al) ≥97.5%. Metal Al powder (≤0.074mm). Among them, the main chemical composition of waste magnesia carbon brick particles and MS95 sintered magnesia fine powder is shown in Table 1.  

• Sample preparation and performance testing

In the test, three groups of samples A, B ,and C were designed, in which the addition amount (w) of waste magnesia-carbon brick particles 5 to 3, 3 to 1 and ≤1 mm was 30% , and 20%, respectively. See Table 2 for the proportion of external additives. First, add waste magnesia carbon brick granules, mix for 3 ~ 5min, then add magnesia fine powder and admixture according to Table 2. After the raw materials of Group A are mixed uniformly, they are naturally stacked in a tray, put in an oven and heated to 200 ° C for 40 minutes, and observe the effect of the amount of different modified asphalt on the spreading of the repairing materials. After being pressed into a cylindrical sample of about φ50mm × 50mm under a pressure of 30MPa, the formed cylindrical sample was held at 1200 ° C for 3 hours in a buried carbon (graphite) atmosphere, and then the normal temperature compressive strength of each group of samples was measured; In the air, the cylindrical samples of groups B and C were heated to 1000 ° C for 2 hours to conduct an oxidation test. The samples were cut in half along the axis of the cylindrical sample, and the oxidation resistance of the samples were oxidized. (% Of the area of the cross-sectional area).

Magnesia-carbon brick test results

• Effect of Modified Asphalt Addition

Effect of different amounts of Al powder and Al + B4C powder

Magnesium carbon brick test conclusions

(1) When 19% (w) modified asphalt is introduced, the spread ability and strength of the sample are good, and a converter hot-state repairing material with better performance can be prepared.

(2) When 3% (w) Al powder and 0.5% (w) B4C powder are simultaneously added as additives, compared with the single addition of Al powder, the compressive strength and oxidation resistance of the patch can be significantly improved.

(3) The prepared hot repair material of the converter has the advantages of good spread ability, strong adhesion of the repaired furnace, fast sintering speed and long service life, and can meet the requirements of converter production. At the same time, due to the low production costs, the number of converter repairs will be reduced, which will produce considerable economic benefits and significant social benefits.

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