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Innovative solutions for lime burning furnaces lining in food, construction, chemical and metallurgical industries


Manufacturing of lime for sugar production industry is provided by lime stones burning at rotating and shaft furnaces. Main criteria to choose proper refractory materials for furnaces lining are: absence of any contaminations, which are able to foul the lime. It could be Chromium containing additives in basic refractories which are able during temperature higher than 1100C to form compounds 9СаО4 CrO3 Cr2O3 with CaO, which contain CrO3, which is biologically active poison.

Traditionally, sugar manufacturers continue to use chromium periclase refractories, but we propose to change them for our mullite compressed refractory materials of MLU-62 grade.

Implementation of our innovative solutions will provide ecological safety of sugar manufacturing, will reduce significantly production self-cost due to economic expenses reduction.

Specialists from Research Institute "Ukrgiprosakhar" have provided complex investigation of various refractory materials, used for burning areas of rotating and shaft furnaces, produced by Ukrainian manufacturers.

Investigations showed that refractory brick MLU-62 is the best due to its physical, chemical and economic parameters, which is able to substitute chemical dangerous cromium periclase refractory material of HP grade.

After plant technologist improvement of MLU-62, it fully confirms lime stone burning furnaces conditions (in particular, increased thermal resistance) and achieved numerous properties which are higher than those in GOST 24704-94.

Research Institute "Ukrgiprosakhar" suggests refractories MLU-62, designed by us, especially for these purposes, for lining and maintenance lime burning furnaces.

Derived characteristics of MLU-62 confirm to use them not only in shaft and rotation lime burning furnaces, but in cement burning furnaces of similar type. So, high aluminous refractory material could be used in spite of magnesia ones of PHC and PShC grades due to its characteristics, most of which are equal and some are even higher.

(see table)

Summary table of comparative characteristics of high-aluminous materials of MLU-62 grade and magnesia refractories, which are too be used at heat units of cement and sugar plants.

 

№№ Names of characteristics acc. grades MLU-62 Mullit, compressed PHC Periclase- chromium (for cement plants) PShC Periclase- spinell (for cement plants) HP 1 Chromium- periclase (for sugar plants)
1 Additional linear shrinkage, % Not more than 0,3 0,7 0,6 0,7
2 Start softening temp, °C, not less than 1550 1500 1540 1500
3 Opened porosity, %, not more than 17 24 23 20
4 Appeared density, g/sm2, not more than 2,68 3,0 3,0 2,95
5 Strength limit during compression, N/mm2, not less than 60 25 30 30
6 Thermal resistance, heat exchange, not less than 8 8 4 2

 

 Most important area for refractory lining of rotating cement furnaces is caking area. Caking area refractories must confirm to following strict requirements:

• High fire resistance and deforming temperature under loading;

• High thermal stability;

• High strength;

• High resistance to chemical interaction of the burnt material.

MLU-62 has all these features.

Besides high quality of physical and chemical characteristics, MLU-62 refractory bricks' price is 20-25% lower than magnesia one. Due to less density of MLU-62, total weight of refractory lining decreases, therefore general loading and tense for the walls leads to significant means savings up to 30%. Also, it's necessary to underline much longer lifetime of such mullite materials.

High demands to ecological safety of food and constructional industries strictly forbid to use refractories with chromium content, because as a result of interaction of chromium spinell with the lime during using, extremely poison and cancerogenic combinations of six-valent Chromium (Cacium Chromates), which are dangerous for health.

Research Institute"Yuzhgiprocement" is recommending for cement plants to use special designed refractories MLU-62 for lime burning ovens.

 
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