US1925940A

US1925940A - Process and apparatus for makin chrome and similar steels

Info

Publication number: US1925940A
Application number: US444762A
Authority: US
Inventors: Kenneth M Simpson
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-04-16
Filing date: 1930-04-16
Publication date: 1933-09-05
Anticipated expiration: 1950-09-05

Description

Sepi. 5, R933., K. M. slMPsoN PROCESS AND APPARATUS FOR MAKING CHROME AND SIMILARST Filed April 16, les@ v of chromium steels.

ing in which:

Patented Sept. 5, i933 PROCESS im APARATTUS EGR ll' CHROME AND SER/HEAR S'IllElElLS Kenneth M. Simpson, New York, N. Y. Application April i6, i930. Serial No. lleii e pimms.

My invention relates to a process and apparatus most particularly adaptable to the making They may also be applied to the making of other steels of high melting point.

Steels of the type of chrome steels are very diicult to melt, and in the process of making the same it is difficult to maintain the mass of metal under treatment suiciently fluid throughout Without the use of excessively high temperatures, and a concomitant poor heat economy.

In my process I use an open hearth furnace for the manufacture of chrome steel, thefurnace being of the usual conventional design, except that'there is disposed beneath the hearth a number of heating nues in addition to the usual overhead heating ordinarily employed in open hearth processes. By the use of my particular apparatus and process I have found that I can overcome many of the disadvantages which are attendant upon the open hearth process for treating steels having high melting points.

In `an ordinary openv hearth furnace all the heat which is imparted to the metal is applied by burning gas, oil or other combustible matter above the hearth. Chrome steels are difficult to melt and to maintain in a iiuid condition, and since the heat must be diffused throughout the bath of metal through the top surface of the metal in the conventional processes, it is necessary to use temperatures far in excessv of those necessary to effect the proper working up of the steel. In my open hearth process I have arranged ues immediately beneath thel bottom of the furnace hearth so that 'heat may be supplied to the steel both at its upper and its lower surfaces. lThe heating of the ues is controlled independently of that of the upper hearth, although the same source of fuel may be used for both. By means of this independent control I can maintain the temperature of theA bottom of the hearth at any desired value. I prefer, however, to maintain a temperature difference of approximately 100 to 150 difference between the upper and-lower surface of the hearth, 'the upper surface of the hearth being maintained at the higher temperature.

The type of furnace which I desire to use in my process is shown in the accompanying draw- Figure 1 represents elevation in section of my preferred form of furnace;

Fig. 2 is a plan view partially in section taken along the line 'A-A of Fig. l; and

(Cl. FJMS) Fig. 3 is a view taken along section B-B of Fig. l;

The furnace 1 is provided with a hearth 2 in which is a charge 3. The fuel lines 4 and 5, preferably gas mains, may lead from the same 00 source of fuel and are provided with controls for regulating the ow of fuel. Fuel from conduit 6 leading from fuel line 4 is burned by means of air Which enters at '1, and this combustion serves to heat the upper surface of the 65 hearth and the metal under treatment-` The bottom of the hearth is heated by means of the burning of gas which enters through conduit 8, into flues 9, air to support combustion being drawn through opening l0. Bafes 1l are 70 interposed in the stream of fuel, the purpose of which is apparent. The products of combustion both from the upper hearth and from the flues 9 are expelled through nue l2.

In my process for the production of chrome, steel the furnace is heated and scrap metal is melted in the furnace and worked down until the carbon contained therein is suitably low, that is .15% or less. Ferrochrome is then added to the molten mass of steel to give the` desired chrome content, which ordinarily will run from.

10 to 20%. When the ferrochrome is entirely melted and chromium has become thoroughly intermingled throughout the mass of steel, the molten metal is 4tapped from the receptacle into 5 a ladle and run into ingot molds. I maintain a temperature on the upper portion of the hearth ordinarily at about 2900 F, the temperature within the flues at the `bottom of the hearth ranging from 2750 to 2800 F. I can 90 vary either temperature by virtue of the independent control of thefuel fed to the upper portion of the hearth and to the flues at the `bottom of the hearth. 'The temperature may 95 be very accurately controlled Without yany great degree of skill on the part of the. operator and the mass of metal being treated can be maintained at a substantially uniform temperature throughout its mass. Thisv enables the temperature of the metal bath to be held Within a range which is not excessively elevated over that necessary for the making of chrome steel, resulting in a very efficient heat economy.

I claim as my invention: 105

1. In an open hearth process for producing chrome steel, the steps which comprise heating the steel at its upper surface from the primary source of heat, and simultaneously heating the steel from beneath its lower portion from an 11'@ independently controlled heating source, the

which is controlled independently of the first y mentioned source of heat.

3. The process described in claim 11 in which the temperature of the primary heat source disposed above the steel is maintained from 100 to 150 F. in excess of that of the auxiliary source disposed beneath the steel.

KENNETH M. SIMPSON.