US3166805A

US3166805A - Leaded steel fume control

Info

Publication number: US3166805A
Application number: US251538A
Authority: US
Inventors: James D Fritz; Kurt K Klein
Original assignee: Colorado Fuel and Iron Corp
Current assignee: Colorado Fuel and Iron Corp
Priority date: 1963-01-15
Filing date: 1963-01-15
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26

Description

Jan. 26, 1965 J, D. FRITZ ETAL 3,166,805

LEADED STEEL FUME CONTROL Filed Jan. 15. 196s INVENTORS JAMES D. FRITZ K RT K. KLEIN 0MM/6., Www/9mm ATTORNEYS United States Patent() 3,166,805 LEADED STEEL FUME CONTROL James D. Fritz, Tonawanda, and Kurt K. Klein, Buffalo,

N.Y., assignors to The Colorado Fuel and Iron Corporation, Denver, Cold., a corporation of Colorado Fiied'}an. 15, 1963, Ser. No'. 251,538

- 6- Claims.` (Cl. 22-139) This invention relates to the production of leaded steel in ingot casting operations, and has for its object the provision of an improved apparatus and process for controlling the lead oxide fumes emitted from such operations. More particularly, the invention is concerned with bottom poured leaded steel ingots and provides means on the top of the ingot mold having means to absorb the lead oxide fumes.

The introduction of lead into ingot steel results in some of the lead being oxidized and released into the Working area as a toxic fume. This has resulted in the use of hoods, exhaust fans and associated equipment to prevent or minimize the inhalation of the toxic fumes by workmen. Such equipment is expensive and not practical for small steel producers.

Our invention provides a very simple and inexpensive means for preventing the release of the toxic fumes from each ingot mold into the surrounding atmosphere. In accordance with our invention, We provide a sand cap on the top of the ingot mold, especially molds for bottom poured ingots, which contains a sand layer or bed into which the toxic fumes can enter and be absorbed. By absorbed we mean that the lead oxide does not escape from the sand and is retained either because of a chemical reaction or a combination of chemical and physical conditions which retain the lead in or on the sand. The lead oxide may be converted to a harmless neutral salt. At the temperature of the sand which is in excess of l000 F. the lead oxide can react with corn-` ponents of the sand and be prevented from entering the atmosphere. We have found that silica sand is a preferred kind of sand which lead oxide reacts with at the high temperatures attained to form lead silicate. However, we may supplement the sand with a material reactable with lead oxide, such as silicon or silicon alloys, or exothermic compositions containing silicon, nitrates and the like. The silicon seems to have a catalytic eifect and the exothermic composition increases the temperature and reactivity. The sand bed may include paper, wood or asbestos to aid in controlling the direction of the lead oxide fumes into the sand bed. The sand bed may be regarded as a ilter which absorbs or renders harmless the lead oxide fumes leaving the top of the ingot mold.

A preferred apparatus of the invention comprises a confining structure (hereinafter called a cap) advantageously mounted over a hot top for making close contact with the top of the ingot mold. The cap is constructed to hold in position a layer of sand of sutiicient depth to serve as a sort of filter bed having the requisite porosity for the lead fumes to enter and become absorbed. ln a preferred embodiment the cap is sealed where it engages the ingot mold and the sand is supported on a screen which permits free entry of the lead oxide fumes.

These and other novel `features of the invention will be better understood after considering the drawings and the following discussion:

FIG. 1 is a perspective, partly in section, of an ingot mold for a bottom poured ingot and a cap in accordance with the invention; and

FIG. 2 is a sectional elevation of another embodiment of the invention.

g"lee The apparatus illustrated in FIG. 1 comprises an ordinary bottompour ingot mold 1, usually formed of top of the hot-top kand making a fairly close contact.

The flange 5 is sufficiently above the lower edge of the frame as to form a depending skirt 6 which forms a pocket 7 at the top of the hot-top for inserting sealing clay. This skirt also serves to center the cap over the hot-top. A grating 8 is placed upon the iiange 5 to give support to a metal screen 9 such as a copper screen. The bed of porous, loose sand 12 which effects the removal of lead fumes is placed upon and is supported by the screen. The bed of sand is suiiiciently deep, for example about twelve inches, that very little, if any, of the lead oxide fumes will pass completely through and contaminate the atmosphere.

FIG. 2 illustrates another modification of the invention comprising an ingot mold 15 for a bottom poured leaded ingot having fitted inside the top a hot-top of a type widely used and known as a C & D hot-top. This hot-top comprises outer supporting parts 16 and 17 formed of steel or iron, which are usually bolted together, an inner pre-formed brick liner 18 and a slurry Wash 19. A sand ring 20 is clamped on the bottom. The joint between the hot-top and the ingot mold is sealed with.

lire clay 20' and the joint between the hot-top and the cap is sealed with fire clay 21.

The steel sand cap 22 of the invention comprisesia rectangular wall 23, a transverse flange 24 which rests on thc top of the hot-top and a depending skirt 25 which lits closely against the inside of the hot-top to hold it in centered position. A steel grid 26 is placed over the iange 24 and the grid supports a screen 27 formed of metal such as copper. The silicasand bed 28 may be any suitable depth, say, up to about 12 inches, but in any event, is suiiicient to remove all the lead oxide fumes. The sand bed can be heated to temperatures above 1000" F. by the heat from the ingot and it has been found that the lead oxide is changed to a lead salt at this or higher temperatures, possibly in reaction with the silica to form a lead silicate. We may also mix with the sand a suitable form of silicon such as the to 98% silicon of commerce whichseerns to have a catalytic eiiect and may even enter into direct reaction with the lead oxide. We may also add to the sand a mixture of silicon and an oxidizing agent such as sodium nitrate to provide an exothermic reaction which increases the temperature of the sand bed and also the reactivity of silica and silicon with lead oxide.

chemical reaction but some may be physically absorbed Y and We, accordingly, referto the removal of the lead oxide by either or both means as absorption.

We claim:

l. The process for preventing the release of toxic lead oxide fumes into the working area from an ingot mold in the production of leaded steel which comprises'introducing molten leaded steel into an ingot mold from which lead oxide fumes are released, placing over the ingot mold containing the molten leaded steel a bed of sand supported over and closing the opening of the mold, said sand containing silica into which the fumes enter, and absorbing the lead oxide fumes in the bed of silica.

2. In the process of claim 1 providing a bed of sand which contains avmaterial of the group consisting of silicon and an alloy of silicon to react with the lead oxide.

ing agent.

4. The combination with an ingot mold for bottom poured leaded steel ingots which comprises a hot-top fmounted on the top of the ingot mold, a cap removably mounted on the hot-top, a screen in the cap, a bed of 4porous sand in the cap supported by the screen closing 'the opening of the hot-top, whereby lead oxide fumes from the ingot -are absorbed in the sand.

Y 5. The combination defined in claim 4 which comprises a grid overlying the hot-tops on which the screen is supported. 1

. 4 metal screen, a bed of sand mounted on the screen, said cap and sand providing a closure for the hot-top whereby fumes released from the ingot enter and are absorbed by the sand.

References Cited by the Examiner UNITED STATES PATENTS 929,688 8/09 Monnot 22-139 1,920,854 8/33 Gathrnann 22-139 XR 1,928,996 10/34 Gathmann 22--139 XR 2,197,259 4/40 Nead 75-129 FOREIGN PATENTS 583,018 9/59 Canada.

MICHAEL V. BRINDISI, Primary Examiner.

ROBERT F. WHITE, Examiner.

Claims

1. THE PROCESS FOR PREVENTING THE RELEASE OF TOXIC LEAD OXIDE FUMES INTO THE WORKING AREA FROM AN INGOT MOLD IN THE PRODUCTION OF LEADED STEEL WHICH COMPRISES INTRODUCING MOLTEN LEADED STEEL INTO AN INGOT MOLD FROM WHICH LEAD OXIDE FUMES ARE RELEASED, PLACING OVER THE INGOT MOLD CONTAINING THE MOLTEN LEADED STEEL A BED OF SAND SUPPORTED OVER AND CLOSING THE OPENING OF THE MOLD, SAID SAND CONTAINING SILICA INTO WHICH THE FUMES ENTER, AND ABSORBING THE LEAD OXIDE FUMES IN THE BED OF SILICA.