SU1300856A1 - Method of manufacturing fused high-alumina cement clinker - Google Patents

Description

The invention relates to the refractory industry, mainly to the production of high alumina cement, used as a binder in refractory concrete. 5

The aim of the invention is to increase strength and reduce specific energy consumption.

The essence of the proposed technical solution consists in preliminarily obtaining in the CaO - Al ^ Oj system the most fusible calcareous aluminate melt, followed by its intense interaction with the more fusible additionally introduced alumina charge component at relatively low temperatures

Heating the mixture to a temperature below 1460 ° C does not completely melt all the compositions of the initial mixture. The non-melting of the mixture in the first stage leads to stratification of the melt during subsequent melting, which negatively affects the quality of the cement obtained: the beginning of setting is lengthened and its strength decreases.

Heating the initial charge to a temperature of more than 1550 ° C leads to an increase in specific energy consumption. The mass fraction of alumina introduced into the pre-molten initial charge should not exceed 25 wt.%. At a higher content of additionally introduced by the reaction:

CaO · 7 Al ^ Oj + 17 A1 _q 0 ₃ primary additional-12ГСа0'2 А1 _g o _r target 20 fusible melt injected refractory pro-alumina along with highly active

CaO'2 A1 ₂ 0 ₃ the formation of a hydraulically inert CaO6 Λ1 0 occurs.

Ώ 3 * deteriorating the cementitious properties of cement obtained from clinker. If colic alumina duct

Improving the quality of cement is achieved due to the complete assimilation of alumina by a highly active primary highly calcareous aluminate melt with the formation of a homogeneous melt of calcium dialuminate and the absence of hydraulically inert compounds and impurities in the reaction products.

Reducing energy costs is ensured by reducing the temperature level of the process ~ by 400 ° C.

The choice of modes and parameters of the proposed method is due to the following.

The limitation of the ratios of lime to alumina within 45–55 (lower limit) and 55–45 (upper limit) is determined by the minimum temperatures of the complete conversion of the initial calcareous alumina charge into a molten state. When these ratios are changed to either side, the initial charge does not completely melt at 1460-1590 ^d C, as a result of which, with an increase in the amount of lime more than 55 wt.%, The clinker mainly contains tricalcium aluminate 3 CaOAl О, which causes rapid hardening of the cement, which worsens its manufacturability and durability. With an increase in the alumina content in the charge of more than 55 wt.% In clinker, the additionally introduced alumina is less than 20 wt.%, Then together with

2 $ CaO · 2A1 _? 0 ₃ , an increased amount of low-melting calcium aluminates (CaO-Al ^ Og, etc.) is formed, which sharply reduce the clinker refractoriness.

The implementation of subsequent melting at temperatures less. 175 ° C leads to an increase in the duration of the process and the appearance of unmelted inclusions of corundum in clinker, which reduces the cementitious properties of cement.

Subsequent melting at temperatures above 1800 ° C is not economically feasible due to a sharp increase in the specific consumption of 40 electricity.

The proposed method is as follows.

The starting components - industrial alumina and lime, in the ratios indicated in the table, are mixed. The half-valuable lime-alumina mixture is loaded into an electric arc furnace, heated to a temperature of 1460-1550 ° C, ^{0 is} maintained at this temperature up to 50 complete melting of the charge. Then, alumina is additionally introduced into the melt and subsequent heating is carried out to a temperature of 1750-1800 ° C with holding at a final temperature for 55 15-20 min until the glyph is completely melted, a significant amount of hydraulically inert CaO'6 Al ^ Og is present, which reduces the cementitious properties.

nozema. The melt is poured into cast-iron bowls and cooled in air for 2 $ h to obtain a hardness of a blade · ra, which is then subjected to grinding.

Modes and parameters of specific examples of the implementation of the proposed method and the prototype method, as well as _; The obtained cements are given in the table.

To study the properties of cement, clinker was crushed to a specific surface area of 10,000 cm ² / g and setting time was determined according to GOST 310.3-76, compressive strength according to GOST 310.4-76 and fire resistance according to GOST 4069-69.

Electricity consumption for melting was determined by the readings of the meter before and after melting, after which the specific electricity consumption was calculated taking into account the amount of clinker smelted.

As can be seen from the table, high-alumina cement from clinker obtained by the proposed method increases the strength of concrete by 1.5-2 times in comparison with cement by the prototype method and has optimal setting time. At the same time, energy consumption for clinker is reduced by 3040%.

The implementation of the method does not require the use of scarce fuel fuel, which also reduces energy consumption.

The resulting cement, due to the absence of metal inclusions, is stable in properties and provides high quality to linings and products based on it.

Example

The composition of the west-alumina fir, wt.%

Additionally entered amount of alumina,.

wt.%

Melting temperature, "C primary post-melting

Properties of high clay cement

Refractory - earlier melting! bone

ABOUT

Setting time, h ° C started the horses after drying, MPa

Specific energy consumption, kW h / t

Noting ?? ®

Lime45

Alumina 55 20 1460 1750 1730 5.2 9 40,0 1560 The inventive method 2 Lime55 Glknozem-45 25 1550 1800 > 1730 2.1 6 32.8 1730 The inventive method 3 IEZEST- - 50 Alumina-50 22 1500 1780 > 1730 m 8 37 1620 The inventive method 4 Lime65 Clay ²⁰ 1540 1780 1550 0.5 2 5 1620 Fir did not melt when

zem-35 primary melting

Lime40 Alumina-60

1540 1780 1800 24.2 38.3 3.5 1615 The same

Table continuation

Example

The composition of the calcareous earth mixture, wt.%

Additionally entered the amount of alumina, wt.%

Melting temperature, ’C

Properties of high-alumina cement primary melting subsequent melting

Refractoriness, * C

Setting time, h start · lo

Konev

6s * after drying, MPa

Specific energy consumption, kW h / t

Note

Lime·

Alumina-50

1550

1800

1500

0.5

10.0 1200

- ——— ——— -— --------- 7 Lime- 50 Clay thirty 1550 1800 1750 20 36 5,0 1900 zem-50 "- ----------- -----—- - ----------- -------- —.— -------- .— =. " 8 Lime- The charge is not fifty 22 1380 1750 > 1730 8 15.1 8.1 1600 melt- Clay at eem-50 primary melting ............ ..... 9 'Lime- fifty 22 1650 1800 > 1730 4,5 9 35,4 2000

Alumina 50

Lime50 Glyloem-50

1500 1680> 1730 80 50 2

1300

It did not completely melt during subsequent melting

Lime 50. Alumina-50

1500 2000> 1730 4.3 9 37.7 2200

Slag alvom inothermal production of chromate82

2120

1730 6 10 18.5 2800 The known method

Lime10

Cois 8 * The chemical composition of the clack, wt.%; A1 _? , O _S 70-76; CaO 6-14;

CtjOj 6-12; Mg 0.5-1.2} FeO 0.1-0.6; SiO _e 0.4-0.8. I t

VNIIIPI Order 1083 Circulation '____ Subscription

Custom Play ave, city of Uzhhorod, st. Design, to

Claims (1)

METHOD FOR PRODUCING FLOATED. HIGH-ALUMINUM CEMENT CLINKER by heating a calcareous-alumina charge and cooling the melt j characterized in that, in order to increase strength and reduce the specific energy consumption, the calcareous-alumina charge containing 45-55 wt.% Lime and 4555 wt.% Alumina is heated to a temperature of 1460 -1550 ° C, after which n the melt is additionally introduced alumina in an amount of 20-25 wt.% Of the total amount of the charge and heated to a temperature of 1750-1800 ° C. _a SS