The f a c t o r y planned and built a section w i t h a b a l l mill (periodic action) lined with silica pebbles for the production of the glaze. The grinding compounds a r e uralite cylinders of d i a m e t e r 20-23 mm. The rotation frequency of the mill is 20-22 rpm. The m a t e r i a l s a r e weighed on scales. The d r y powders a r e f i r s t loaded into the mill for composition No. 1, these a r e ground f o r 4 h, and then water and sulfite lye are added, a f t e r which grinding is done for 6 h. F o r glaze No. 2 the dry powders with an addition of water and lye a r e wet milled for 10-12 h. The glaze slip is s c r e e n e d through 0 . 5 4 - m m m e s h , and then it is poured into a glaze container. The g r e e n a r t i c l e s a r e blown with c o m p r e s s e d a~ir, placed in boxes, and, using a bogie, lowered into the glaze. Because of the possibility of settling in the glaze it is periodically s t i r r e d with a p r o p e l l e r m i x e r . The glaze coating is dried in natural conditions. The goods in the tunnel c a r a r e placed one high (see Fig. 1). Firing is done at 1350~ The goods coated with glaze have a good appearance: the graphite is not burnt out (Fig. 3). E x p e r i m e n t a l g r a p h i t e - - c h a m o t t e nozzles were tested at the Nizhnetagil' sk Steel Combine, the G orkii Krasnoe Sormov F a c t o r y , and the Zlatoustovsk Steel F a c t o r y . Nozzles with the coatings and those fired in coke filling had the same s e r v i c e p r o p e r t i e s . Anarmual savings of 18,400 r u b l e s was obtained f r o m the use of the p r o t e c t i v e coatings. LITERATURE 1.

2, 3. 4.

CITED

R e p o r t on Subject No. 01218. Development of Bodies, Glazes, and Technology for Making Carbon-Containing Nozzles for the Casting Conveyer of the Gorkii Automobile F a c t o r y [in Russian], UPI, Sverdlovsk (1972)o Report. Development of P r o t e c t i v e Coating for Carbon-ContainingArticles-Bogdanovich R e f r a c t o r i e s F a c t o r y [in Russian], Bogdanovich (1977). I n v e n t o r ' s Certificate No. 563430, V. G. Sivash, V. V. Saparov, M. N. Kaibicheva, et al., Otkrytiya, Izobret. P r o m . Obraztsy, Toy. Zn., No. 24 (1977)o I n v e n t o r ' s Certificate No. 478822, P. S. Mamykin, M. N. Kaibicheva, A. D. K_homutinina, and D. L Yuzvuk, Otkrytiya Izobret. P r o m . Obraztsy, Toy. Zn., No. 28 (1975).

MAKING

GATE

VALVE

REFRACTORIES

LADLES

USING GK ALUMINA

N . V. K o n e t s k i i , A. and R. N. Gol'dinova

A.

M~khin,

FOR

STEEL

UDC 666.762.t!: [621,746.323 : 669.18.046.518

The Semiluksk Refractories Factory haz developed and is perfecting a method a r t i c l e s for the gate valves of steel ladles using GK alumina.

of maki1~g c~du~

This alumina is added to the fine-milled p a r t of the batch instead of the fine-milled corundum chamotte (not l e s s than 93% A1203), which is made f r o m techrdcal alumina and kaolin, used in the conventional technology. The f i n e - m i l l e d G K alumina is obtained by milling in a vibration mill for 1o5-2 h, while the p r e p a r a t i o n of the f i n e - m i l l e d bond f r o m corundum chamotte is a lengthy and laborious p r o c e s s , which includes producing the chamotte, milling it i n a t u b e m f l l , and final grinding in a vibration mill for not l e s s than 6 h. We p r e p a r e d two e x p e r i m e n t a l batches of tiles g r a d e 3S-60 in amounts of I and 8 tons. The raw m a t e r i a l s for these batches were corundum ehamotte fractions 2.0-0.5 m m (54.9% 2-1 ram, 42.3% 1-0.5 mm, 2.8%< 0.5 ram) and finer than 0.5 Iron (14.6% 1-0.5 ram, 85.4% < 0.5 nun, including 5.9% < 0.089 ram) and alumina GK containing, a f t e r 2-h grinding in the M-400 vibration mill, 0.3% fraction plus 0.06 m m and at l e a s t 12% finer than 2 ~m. To speed up the milling of the alumina, a waterproofing agent in the f o r m of GKZh-1 0 wad added in amounts of 0.02-0.03%. The vibromilled GK alumina contained 99.66% A120~ and 0.3% Fe203; the chamotte -94.8% A1203; the w a t e r absorption of the chamotte was 3.7-4.2%. Semiluksk R e f r a c t o r i e s F a c t o r y .

16

T r a n s l a t e d f r o m Ogneupory, No. 1, pp. 16-18, January, 1980.

0034-3102/80/0102-0016 $07.50 9 1980 Plenum Publishing Corporation

TABLE 1. Results of Testing Finished Goods Composition * of Lood% prepared I ~ l technology (according to using new technology (1978 data) Quay- ~977 d a ter

I

t

a

) open porosity.

tpparent density,g ~m:. %

a-~par-~ntdensity

3,38 3,38 3,18--3,50

open porosity.

%

I dcm~

7,3 4,1~11,5 7,3 -3,2--12,5 7,3 3,1--11,9

3,43 3,22--3,56 3,43 3,24--3,55 3,43 3,30--3,51

10,6 8,3~12,9 9,7 5,9--13,6 9,6 4,3~14,0

3,23

3 , ~

n

Ill

"

*The num-erator shows the averages, and the denominator the range of values.

The compound m a d e of 65% c o r u n d u m c h a m o t t e and 35% v i b r o m i l l e d GK was m a d e in the SM-14 m i x e r . The g r a i n - s i z e c o m p o s i t i o n of the compounds was 19.1-19.7% 2-1 ram, 20.5-23.6% 1-0.5 ram, 56.362.2% < 0.5 ram= including 38.0-40.5% < 0.06 ram. The m o i s t u r e content of the compound was 3.5-3.8%. The a r t i c l e s w e r e molded on the F-1238 friction p r e s s with an i n c r e a s i n g i m p a c t force: total n u m b e r of blows 10. The a p p a r e n t density of the g r e e n b r i c k was 3.18-3.22 g / c m 3. The kiln c a r was loaded with goods having a m o i s t u r e content of t h e r m a l c r a c k s the setting s c h e m e on the c a r s was a l t e r e d as follows: four s i d e s with brick, but they w e r e c o v e r e d at the top with corundum goods) or with s h e e t s (obtained through c r a c k i n g in firing of corundum 1630-1650~ i n s t e a d of the 1510-1530~C u s e d f o r the o r d i n a r y method.

not m o r e than 0.5%. To reduce the the g o o d s w e r e not only p r o t e c t e d f r o m tiles ( s c r a p f r o m cutting insulating briquet). The firing t e m p e r a t u r e was

The p r o p e r t i e s of the t e s t goods a f t e r firing a r e : shrinkage, 3.6-5.2%; a p p a r e n t density, 3.38-3.43 g / cm3; open p o r o s i t y , 7.6-10.5%; c o m p r e s s i v e strength, 196-200 MPa; A1203 content, 95.66%; and Fe203, 0.38% (averages). The y i e l d of a c c e p t a b l e t i l e s a f t e r firing i s 99%. The e x p e r i m e n t a l tiles a r e being t e s t e d for casting s t e e l of different types, including 1KP and 3KP at the W e s t e r n Siberian Steel F a c t o r y . T e s t s showed that the u s e of t h e s e t i l e s for casting one heat of s t e e l c o m pletely excludes l e a k a g e (underflow) of m e t a l , while in the casting of steel using o r d i n a r y tiles the h e a t s c a s t with l e a k s equaled 2.6%. Using 29 s e t s of the e x p e r i m e n t a l t i l e s we t e s t e d the casting of two h e a t s in turn. Out of 58 heats we c a s t 52 without b r e a k i n g the technological i n s t r u c t i o n s , of which 41 took place without m e t a l l e a k s , and 11 with s m a l l l e a k a g e . The u n s a t i s f a c t o r y m e t a l c a s t i n g s (3%) w e r e obtained mainly b e c a u s e of the p a s s a g e of m e t a l between the t i l e s o v e r the e n t i r e s u r f a c e . The tile s u r f a c e was even and undamaged in this c a s e . Replacing the

TABLE 2. Properties of Experimental Specimens* CoITIp.

Ahq

coat. in No.t ham otto

Content, %, in comp. of fract., mm App.dens.of] . . . . . . I-~el-~mg[green back, apparent ~-,

,-o.~

<0,~ 1"~176 [g/cmS [

68

33,8

19,6

46,6

38,8

2,76--2,83

85

29,9

25.3

45,2

38,1

3,01--3,06

68

30,6

21,7

47,7

39,0

2,78--2,84

85

32,1

21 ,O

48,9

40,2

3,05--3,10

Prolmrties after firing open porosity, ~ompressive

~trength, MPa ~o

demity, g/em" 2,83 2,80--2,98 3,07 3,06--3,09 2,91 2,90--2,92 3,11 3,10--3,12

Content,~ shrinkage.

14,4 13,8--15,1 13,9 13,2--14,3 13,15 ]2.5--13,8 10,9 10,6--11,8

109 120--115 118 116--120 122,5 120--125 130 125--140

AI=O3

[ Fe=Os I

2,1--2,4

76,10 I 0,60

2,2--2,5

Not det~d

]

2,7--2,9

77,9

0,59

2,8--3,0

89,25

0,58

*Fixing temperature of specimens of compounds Nos. 1 and 2 -- 1510=1530"C; of compounds Nos. 3 and 4-- 1630"C. TMoistute content of compounds Nos. 1 and 2 - 3.8%of compounds Nos. 3 and 4 - 4%

17

collector after the first heat and also damage to the tiles during burn-through of the channel did not always facilitate the use of tiles for casting the second heat. The production of the corundum articles far gate valves using the new method on average reduced their open porosity by 2% (Table 1) and cut loss due to radial cracks. In the third quarter of 1977 the loss due to such cracks after firing was 6.5%, and for the third quarter of 1978 it was 0.1%o The development of the new technology also released 35% of the corundum chamotte used for making fIne-milled bond We also made laboratory tests to clarify the possibility of substituting corundum chamotte with highalumina chamotte containing 68 aad 85% A1203. The experimental articles were made in laboratory conditions using the ordinary (compounds Nos. 1 and 2) and the new compound (compounds Nos. 3 and 4) technology. The properties of the goods are shown in Table 2. The properties of the test goods made with the use of vibromiUed GK alumina and high-alumina chamotte containing 68 and 85?0 A1203 and fired at 1630-1650~ correspond to the properties of corundum goods made for the gate valves of steel ladles (according to TU 14-199-31-75). The nature of the wear in the test articles is identical to that of corundum goods. CONCLUSIONS A technology was developed for making articles for the gate valves of steel casting ladles ensuring high service factors. It was found possible to use high-alumina chamotte instead of corundum.

18