US2063579A - Furnace - Google Patents

Description

Dec. 8, 1936. .1. o. BETTERTON FURNACE Original Filed Jan. 50, 1933 Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE FURNACE Jesse 0. Betterton, Metuchen, N. J., assignor to American Smelting and Refining Company, New York, N. Y., a corporation of New Jersey Original application January 30, 1933, Serial No. 654,176. Divided and this application July 25,

1934, Serial No. 736,894

4 Claims. (01. 26619) '5 high state of purity and possessing an excellent white color tone.

By the present invention white antimony oxide free from lead or at most containing only insignificant or permissible amounts of that. element is volatilized directly from antimony-lead alloys having a lead content within the range of ap-' preciable quantities to approximately 60%.

In general, the invention contemplates establishing an active, thin, molten, mobile slag film, oil-like in appearance, upon the surface of a molten antimony-lead bath in the presence of a suitable oxidizing atmosphere and so stabilizing the system that practically pure white, leadfree antimony oxide is volatilized from the supernatant slag film regardless of the concentration of lead in the bath within the limits heretofore specified.

Among other features the invention provides an apparatus in which the indicated operations may be carried out, which apparatus is adapted for ready manipulation and is of a high degree of simplicity of construction.

The present application is a division of application Serial No. 654,176, filed January 30, 1933 which issued as Patent No. 2,035,454 on March Although the novel features which are believed to be characteristic of this invention will be particularly pointed out; in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawing forming a part thereof, and in which Fig. 1 is an elevation of one type of apparatus suitable for practicing the method of the invention;

Fig. 2 is an elevation taken along the line 2-2 of Fig. 1 and at right angles to the elevation of Fig. 1.

Referring more particularly to the drawing, it will be seen that the illustrated form of furnace assembly comprises a steel casing I lined with suitable refractory material 2 with beams 3 supporting a cast iron melt and fuming pot 4. The furnace is mounted on trunnions 5 and may be tilted by suitable manipulation of the worm gear 6. A burner 1, opening into heating chamher 8 is provided for heating the antimony-lead bath 9 in fuming pot 4 while flue Ill provides an exit for waste combustion gases. A hood ll, adapted to fit snugly over fuming pot 4 is provided with adjustable ventilators l2 and an inner cylinder I3, the purpose of this cylinder 6 being to control the velocity of the air passing over the surface of the bath 9, the velocity of the air increasing as the cylinder I3 is lowered towards the bath and decreasing as the cylinder is raised. The cylinder I3 is capable of adjust- 10 ment both in respect to hood II and the surface of the bath 9 by suitable means (not shown) attached to chains M. A flue l5 leads from hood H to suitable fume recovery apparatus (not shown) employing the above described apparatus. 5

The production of antimony oxide possessing the desired improved properties may be carried out as follows:

The furnace is brought to the upright position and suitable antimony-bearing material, for ex- 20 ample, antimony dross containing over 40% antimony and the balance substantially lead, is charged to the pot 4. The metal may be melted and brought to a suitable temperature by heat derived from burner I and any dross formed 25 during the melting down operation removed from the molten bath. Hood ll may then be lowered over the fuming pot and the inner cylinder l3 adjusted so that the lower edge is a suitable distance, for instance, approximately 9", above the 30 surface of the bath, and the desired distance may be mainta ned by suitable readjustment as the metal level falls during the operation of the process due to depletion of the antimony content of the bath by volatilizatlon of antimony oxide. 35

Upon removal of the melting down dross and exposure of the clean molten metal to the atmosphere, a very thin oil-like mobile slag film forms on the surface of the bath 9 and antimony oxide, white in color and practically free from 40 lead, rapidly volatilizes. As a thin hard crust. appears on the slag film after a time which will depress the volatilization of antimony oxide if the crust is allowed to accumulate, the slag film is gently worked from time to time, for example, 45 by an iron tool, in order to maintain the thin, molten, mobile slag film and to prevent and break up crust formation. When necessary the surface should be skimmed with a perforated skimming tool or other suitable device to remove accumulated crust from the system. The metal should be maintained within a controlled temperature range, for instance, approximately 1375 F. to 1500 F., and air admitted in required and regulated amounts through vents l2 in hood 55 H, care being taken to prevent rupturing the surface of the slag film or appreciable cooling thereof by the incoming air.

By thus maintaining conditions of equilibrium between the molten bath, the thin slag film and the oxidizing atmosphere, fuming of practically pure antimony oxide may be effected until the antimony content of the bath is depleted to approximately antimony.

The fume as it arises from the kettle may be conducted out through the inner cylinder l3 of hood H to suitable recovery apparatus, for example, a baghouse, afan (not shown) preferably being utilized in this operation.

When the fuming operation is completed, for example, when the antimony content of the bath falls below 40% the heat may be turned off, the burner I moved out of the way, the hood H raised and the kettle emptied by suitably operating the worm gear 6 to tilt the furnace. Thereafter the furnace may be brought back to its original position, additional antimony bearing material charged to the pot 4 and the operation repeated.

It will be noted that the hood H is made of two portions or sections, one of these being of substantially uniform diameter, the other flaring outwardly to fit over the rim of the receptacle or kettle 4. The slope of the flaring portion of the hood is such that the air inlet vents l2 will direct air directly onto the surface of the bath 9, so that the surface will be swept by the air currents thus admitted. The portion of the hood which is of uniform diameter serves as a guide for the adjustable member I3 during movement thereof, assuring proper positioning thereof relative to the bath 9.

It is to be clearly understood that the preceding specific example is given merely for the purpose of illustration and is in no sense to be construed as limiting the broad scope of the invention; and it will be understood therefore that it is intended and desired to embrace within the scope of this invention such modifications and changes as may be necessary to adapt it to varying conditions and uses.

What is claimed is:

1. A volatilization furnace comprising the combination with a casing, of a melting and fuming kettle mounted in the casing adapted to receive a charge and to enable the surface of the charge to be swept with air, means for heating the kettle to melt the charge therein, a hood fitting over the kettle in close relationthereto and enclosing the rim thereof, the said hood having an upwardly converging portion adjacent to the kettle and a flue communicating therewith, air intakes in the upwardly converging portion of the hood positioned to direct sweeping currents of air onto the surface of the charge in the kettle to promote fuming of volatile oxide products from the charge and to carry the said products through the flue, and adjustable means for controlling the air intakes for regulating the amount of air sweeping the charge in the kettle at any given time.

2. A volatilization furnace comprising the combination with a casing, of a melting and fuming receptacle mounted in the casing adapted to receive a charge and to enable the surface of the charge to be swept with air, means for heating the receptacle for melting the charge therein, a hood fitting over the receptacle in close relation thereto and enclosing the rim of the receptacle, adjustable ventilators in the hood for admitting currents of air directly to the charge for sweeping over the surface of the charge for oxidizing the same and to promote fuming of volatile oxide products from the surface of the charge, an adjustable draft-controlling member positioned in the hood and adapted to be positioned at variable distances above the charge for regulating the draft of air contacting with the charge, and means for adjusting the height of the draft-controlling member above the charge.

3. A volatilization furnace comprising the combination with a casing, of a melting and fuming kettle mounted in the casing adapted to receive a charge and to enable the surface of the charge to be swept with air, means for heating the kettle to melt the charge therein, a hood fitting over the kettle in' close relation thereto and enclosing the rim thereof, air intakes in the hood positioned to admit sweeping currents of air directly over the surface of the charge in the kettle to promote fuming of volatile oxide products from the charge, said air intakes having adjustable means for controlling the amounts of air passing over the charge.

4. A volatilization furnace comprising the combination with a casing, of a melting and fuming kettle mounted in the casing adapted to receive a charge and to enable the surface of the charge to be swept with air, means for heating the kettle to melt the charge therein, a hood fitting over the kettle in close relation thereto and enclosing the rim thereof, the said hood having an upwardly converging portion terminating in a portion of approximately uniform cross-section and a flue communicating therewith, air intakes in the converging portion of the hood positioned to direct sweeping currents of air onto the surface of the charge in the kettle to promote fuming of volatile oxide products from the charge and to carry the said products through the flue, an adjustable draft-controlling member movably suspended in the hood and adapted to be adjustably positioned at variable distances above the charge for controlling the draft of air contacting with the charge, means for operating the draft-controlling member of raising and lowering the same relatively to the charge, the said portion of the hood of uniform cross-section serving to guide the draft-controlling member during adjustment thereof relatively to the charge and means associated with the flue for collecting fumed products.

. JESSE O. BETTERTON.

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