Table 1. Charge Materials and Blast Conditions Blast Conditions Variable
Total blast (air + O2enrichment) [m3 Blast temperature [C/F]
Total %O2 %O2
in the blast enrichment
Flow of pure oxygen added [Nm3 Relative humidity [%]
Ambient Temperature [C/F] Charge Conditions Material
Weight [kg] Size [m]
Coke 3.0
0.037-0.078
Metallic Charge White iron Steel
Presentation Briquettes Lump
Residual Humidity 0.50
CaO 53.5 * The chemical compositions provided by the manufacturer
Te first was to change from intermit- tent tapping to continuous tapping. Te second modification was to extend the time of operation from a few hours to six hours. Te latter was necessary to achieve steady state conditions inside the cupola prior to quenching. Additional modifications facili-
2
tated the accuracy of the experimental measurements. Te first change was to enable the careful removal of the cupola contents by cutting the cupola stack into five removable flanged sections. Te locations of the sections are shown in Figure 1. Viewing ports were installed at five sections to enable the retrieval of iron, slag and coke samples prior to quenching. Te ports were located at 4 in. (0.1m) intervals starting at tuyere level and extending to 16 in. (0.4m) above. Te charge material and blast
condition data are provided in Table 1. Te material charges contained equal weights of cast iron and steel.
Procedure Several modifications were
necessary in order for the cupola to perform the same as larger commercial cupolas.
of the weight of metal and alloy. Cop- per (Cu) was added to the cast iron at 0.8%. Steel contained 0.007% Cu. Tis difference enabled the determination of the proportions of cast iron and steel in a liquid metal sample based on its Cu content. Te following information was taken
It contained two types of silicon car- bide (SiC): lump and briquettes. Te blast was enriched with 5.8% oxygen (02
). Te coke weight was about 24%
during the test: 1. Temperature of the metal in the con- tinuous channel was measured with an immersion pyrometer.
2. Iron samples were taken in the cupola trough for characterization of the final iron composition. The samples were poured into a copper mold in order to avoid the precipita- tion of free graphite. The analyses were performed with Optical Emis- sion Spectrometry (OES).
3. The concentrations of O2 and CO2
were measured in the take-off gas before it entered the burner.
4. The melt rate was determined by the amount of metal charged over time.
Te cupola was operated under steady
conditions for six hours. At time zero, the air blast was shut off and replaced with a blast of nitrogen about three minutes later. About five minutes later, water was introduced through the charge door and water was sprayed on the cupola shell. A thermocouple located at tuyere level monitored the change in temperature. Te temperature measured at tuyere level at the start of the water quench- ing process was about 2,732F (1,500C). It required about 7.5 minutes for the temperature to be reduced to the freezing point of cast iron. Te entire quenching process took about 16 minutes. Once cupola temperatures allowed
the removal of materials, the archeologi- cal examination began. Materials were removed and stored in 18 layers. Te thickness of each layer was approxi- mately 4 in. (100mm). Once the charge materials contained within a section were removed, the section was removed to allow access to the materials below. A variety of analytical techniques
were used to examine the cupola contents. Tese included: photography to record general conditions; optical
August 2013 MODERN CASTING | 43
Limestone 1.0
0.025-0.038 Silicon Carbide
Lump 0.15 0.02
Chemical Composition of Charge %C 3.32
%Si 1.40
0.062 0.002
Silicon Carbide* %SiC 36.00 98.0
Characterization of Coke Ash 8.50
Characterization of Limestone MgO 0.89
Briquettes 0.45 0.05
%Mn 0.44
0.469
%Free Carbon 27.00 1.00
Volatiles 0.60
SiO2 0.83
Metallic Charge
Steel 6.0
0.002 %S
0.068 0.012
%Cement 10.00 0.50
Carbon 90.4
Al2 O3 0.47
White Iron 6.0
0.01
%Cu 0.80
0.007
%SiO2 27.00 0.50
Sulfur 0.52
Fe2 O3 0.13 /s] /s/ft3 /min] Value
0.108/229 410/770 26.83
5.83
8.00E-3/17 65
24/75
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68