Melting furnace lining stove-sand Process Method

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Melting furnace lining stove-sand Process Method

Time: 2019-09-06

The length of the furnace depends mainly on the nature of the lining material and whether the smelting sintering process is perfect.

1. Material of the lining:

Acidic lining, the bricks should be free of impurities such as a pure ( S I 0 2 content of greater than 99 . . 3% high-grade quartz sand) in which the impurity content of F. E 2O3 ≤ 0 . . 5% , C A 0 ≤ 0.25%; A l 203 ≤ 0.2%; moisture ≤ 0.5%. In the lining sintering process, the crystalline state of quartz sand at the sintering temperature should be changed to phosphorus quartz . Otherwise , when the furnace is smelting , the temperature of the lining will occur. severe frequent changes , prompting crystalline quartz has also undergone change , will have a huge impact on the furnace . so lining sintering include ovens , it is an important part of the crucible to obtain excellent high temperature performance. In general , in order to improve the strength of the lining , the amount of boric acid can be appropriately increased .Specific ratios refer to the table below .

Table 1 Relationship between the amount of boric acid added to the acid furnace lining and the smelting temperature

Serial number	material	Casting temperature ( °C )	Boric acid	Quartz sand	Smelting temperature ( °C )	Keep sintering time ( hours )
1	Gray iron	1400	1.8- 2.5%	98.2- 97.5%	1450	3-4
2	Gray iron	1400-1450	1.2- 2.0%	98.8- 98.0%	1480	3-4
3	Gray iron	1450- 1500	1.0- 1.7%	99.0- 98.3%	1500-1525	2-3
4	Gray iron	1500-1550	1.0- 1.6%	99.0- 98.4%	1550	1-2
5	Gray iron and high carbon steel	1550- 1600	0.8- 1.5%	99.2- 98.5%	1600	0.5 or more
6	70.6% medium carbon steel	1600	0.5- 0.9%	99.5- 99.1%	Casting temperature	0.3-0.5

For the alkaline lining , magnesia is used as the main material . The formulation can be referred to Table 2 and Table 3. The large tonnage and high temperature bismuth are preferably prepared by fused magnesia and fused A i2 03 .

Table 2 ratio of alkaline lining materials

Serial number	Electric furnace capacity ( kg )	坩埚Materials (%)			Magnesium sand particle size composition (%)
Serial number	Electric furnace capacity ( kg )	Magnesia	Fused magnesia	Electrofusion A l2 03	<1( mm )	1-3 ( mm )	3-5 ( mm )	5-20 ( mm )
1	10-30	70-80	30-20		25	45	30
2	150-500	50-20	50-80		20	35	25	20
3	≥ 1000		70-80	30-40		180 mesh 40%	50-140 mesh 32%	20-40 mesh 28%

Table 3 ratio of binder for alkaline lining

Name	Binder composition
Name	Water glass	clay	Boric acid
Boric acid			1.5-2.5
Water glass	5
Water glass - boric acid	5
Clay - boric acid		2-2.5	1.5-1.8

Table 4 oven time reference table (150 kg )

Power (KW)	20	30	40	50	60
Time ( minutes )	60	60	60	120	120

Oven time reference table (250-500 kg )

Power (KW)	30	40	60	100	150
Time ( minutes )	60	60	60	120	120

Oven time reference table (1000 kg or more )

Power (KW)	50	60	70	80	100	120	140
Time ( minutes )	60-120	60-120	60-120	60-120	120-240	120-240	120-240

2. Filling and tanning of the lining :

First, the quartz sand is dried ( temperature 300 °C , time ≥ 12 hours ). The quartz sand should be pure , and after magnetic separation , it should not be mixed into slag , wood chips , broken iron, etc. ) .

Then the induction coil against the inner wall of the sleeve into a circle 5 insulating layer cotton mm thick made of stone , in a mix of quartz sand mixture gradually into the stove-sand , lining should be layer by layer filling , each The thickness of the layer should not exceed 40-50 mm . Only the thickness of the first layer is more than 50 mm . After tamping with the tamping rod , tamping with a flat hammer . When filling the second layer , the surface of the first layer should be drawn . and clear residual material , before the insertion of the material stove-sand next layer. When filling the bottom of the furnace , the thickness of each packing is 30-40 mm , and then the upper part is removed, and then the hammer is leveled .

Discharge crucible mold , the crucible mold to be leveled , and measuring the crucible mold and the inductor internal radial clearance , to ensure the circumferential direction of the gap uniformly , After adjustment , increase was in the crucible mold , and with a wooden ramp wedge to four weeks administration is fixed , in order to prevent the stove- sand loose when . Therefore lining and filling ramming must have specialized tools . when the stove-sand when the roof , preferably stay 20 is mm height of about , the original stove-sand add material on the basis of 2-3% of boric acid In this way, a hard layer of sintered layer can be obtained . In addition , a layer of water glass is applied to the top of the die and the discharge port , and a small amount of water glass is added with 35% of quick-drying cement and 65% of the furnace sand . The composition is composed of a mixture of appropriate consistency and can be kneaded into a group. The furnace sand can also be used ( 10% water glass or 20% refractory clay can be added into the furnace sand with 10 % refractory clay for furnace sand ).

Low transmission power , slowly heated crucible mold , a moisture sufficiently evaporated , the specific time and shown in Table 4 carried out . , And optionally a crucible form is removed , when the temperature reaches 800-1200 after about degrees Celsius , can be divided into several charged return clean rust-free material , with 90% or so of the power charge is heated to melting , after heating to the sintering temperature in table 1 to maintain a certain time , and then continuous melting 2-3 furnace. In order to obtain a good glazed crucible , the first furnace can only be returned with clean and rust-free small pieces , then add appropriate amount of broken glass , 150 kg melting furnace plus 0.5k g ; 250 kg melting furnace plus 1.5 kg ; 500 kg melting Furnace plus 2k g , 1000k g melting furnace plus 4 kg ; 2000 kg melting furnace plus 8 kg is appropriate.

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Melting furnace lining stove-sand Process Method

Time: 2019-09-06