US1364838A - District - Google Patents

Description

UNITED STATES ATELNT @f'f'ltiid.

RICHARD FRANCHOT, OF NIAGARA FALLS, I TEVJ YORK, ASSIGNOR TO FERRO CHEMI- GALS, INC., OF WASHINGTON, DISTRICT OF COLUMBIA, A CORPORATION OF DELA- WARE.

MANUFACTURE OF GAS AND CYANIDS.

No Drawing. Application filed July 8,

T 0 all whom it may concern:

Be it known that I, RICHARD FRANCHOT, a citizen of the United States, residing at Niagara Falls, in the county of Niagara and State of New York, have invented certain new and useful Improvements in Manufacture of Gas and Cyanide, of which the following is a specification.

This invention relates to the manufacture of gas and cyanids; and it comprises a method wherein air is blown through ignited fuel at the highest possible temperature, the resulting gas is passed at a temperature of over 1000 C. through a charge of shaped masses of iron, carbon and alkali containing enough carbon and alkali to enable retention of the cyanid formed within such masses, and the resulting cooled and enriched gas is collected for use; all as more fully hereinafter set forth and as claimed.

In the ordinary operation of the ordinary type of gas producers the gas delivered is of poor quality, having but little heating value when burnt cold and delivering no great power in a gas engine. Air, being (roughly) 20 per cent. oxygen and 80 per cent. nitrogen, on being sent through a bed of ignited fuel should give a gas containing 33 per cent. CO since oxygen doubles in volume in uniting with carbon to form carbon monoxid. Such a richness as this however is never approached commercially although it is well known that it can be attained in a hightemperature producer such as those of the blast furnace type or slagging producers. The reasons for this usual poverty of product are several, one being that for the sake of convenience in dealing with the fuel ash it is deemed well to run the active zone of the producer at a temperature below that at which the ash will clinker or slag. Another is that heat in the gas, except where direct gas firing of furnaces is used, is not regarded as advantageous and much of this extra heat is utilized to make more gas, as well as a temperature control effected, by feeding endothermics (steam or products of combustion) with the air.

It is an object of the present invention, to make a gas of the richness of the high-temperature gas stated and still further enrich this gas while at the same time utilizing the heat. To this end, I produce a high tem- Specification of Letters Patent.

Patented Jan. 4, 1921.

Serial No. 309,419.

perature producer gas of more than theoretical richness in a slagging gas producer. The producer is charged with fuel, which may be coke or anthracite, or bituminous coal and is run with a hot blast so as to produce a maximum temperature. Lime or limestone is charged to slag the ash. Since the CO of the limestone unites with carbon to form 00 the gas is correspondingly enriched. F or effective slagging of the usual lime-silica-alumina slag, a temperature in excess of 1250 C. is necessary. Iron cannot well be used to increase slag fusibility since it is reduced to metal under the conditions. But a little iron ore or highly ferruginous slag is usually added to the producer charge as the presence of iron catalytically promotes the formation of CO. A good flux is the leach mud obtained in the conversion of chrome iron ore to soluble chromate. Usually the producer temperature will run up to 1400 or 1500 in the hot zones. The gas drawn off from this hot zone, since it has been withdrawn from contact with carbon at a temperature in excess of 1000 C., is substantially free of carbon dioxid, and is like the gas from the boshes of a blast furnace, notable in that it contains more than the theoretical amount of CO, namely from 34% to 35 per cent. As a matter of fact, gas suitable for the purposes of the present invention may be tapped from the boshes of any iron furnace.

This gas I enrich at the expense of its sensible heat, using a well known reaction by virtue of which nitrogen, in the presence of carbon, alkali and iron (iron acting as a catalytic) yields carbon monoxid and cyanid. All the oxygen of such an alkali as Na CO, or NaOH becomes carbon monoxid at the expense of the carbon present. In operating in this way, enrichment is both by the addition of new CO and abstraction of nitrogen. In utilizing this principle it is possible to take a gas of M00 C. containing the theoretical amount of CO namely about 33 per cent. and raise its CO percentage to 0 per cent. or better in dropping its temperature to say 800 C. In order to secure the best results it is desirable to pass the hot gas into contact with a large mass of an intimate mixture of carbon, alkali and iron, and the mixture should be as pervious as possible. Such a mixture may be made by molding balls or bricks of magnesia 20 per cent, coke 15 per cent, soda ash 15 per cent. and iron or its equivalent of iron OXlCl 50 per cent. The iron should be finely divided. The magnesia should be in granules of about wheat size, the soda ash and coke powdered. All should be intimately mixed, molded with a little hot water into balls or bricks and dried at about 100 C. These balls will have considerable mechanical strength and be freely pervious to gases. After a time when the enriching power of the balls ceases or slackens because of the conversion of sodium carbonate into sodium cyanid the balls may be removed and leached to recover the cyanid. Or they may be simply steamed to convert the nitrogen of the cyanid into ammonia which is afterward recovered. In the first mode of operation the leached balls still contain much of their carbon and all of their iron. They may be soaked in a solution of sodium carbonate and reused until the proportion of carbon becomes too low when they may be reground with fresh carbon. and remolded and so on until the proportion of ash constituents (from the coke) becomes too great. By using charcoal or petroleum coke in lieu of ordinary coke the period of life may be much extended. In the second method of operation, that is, steaming, the soda still remains with the balls and they may be reused until the proportion of carbon becomes too little, when they must be again worked up. The life of the balls or bricks may be prolonged by introducing into the hot gas hydrocarbons as coal gas, natural gas, or petroleum oil. These break up at the temperatures specified and set free carbon in and upon the balls. A little carbon may also be deposited from the producer gas by periodically lowering the temperature, by reducing the relative volume of hot gas, or after steaming.-

In any method of operation after a time the material of the balls must be renewed as they become too much charged with ash constituents of the fuel to render further utilization desirable and they break down physically. From this material it is difficult to recover all the soda by leaching since much of the soda is combined with ash constituents in insoluble form. It is also diiiicult to recover the iron. an advantageous Way of utilization of these waste materials is to simply add them to the charge in the producer. Under the conditions in the producer the iron is melted and may be collected in the usual way while the silicates, etc. are slagged and the sodium content converted into cyanid. At the temperature eX- isting in the producer this cyanid is in the form of vapor or fume and it goes forward with the hot gas, collecting in the brick'ets.

The collected sodium cyanid is added to that which forms in the use of the balls and is obtained in the leaching operation. After passing from the balls the gas still contains sensible heat which may be imparted to the air blast of the gas producer.

lVhile I have spoken specifically of sodium carbonate, it will be understood that where cost conditions justify potassium carbonate can be used. As a matter of fact potassium carbonate, apart from the question of cost, is a better alkali for my purposes than sodium carbonate since it cyanids faster and the amount of cyanid, therefore, which can be formed in dropping the temperature of the hot producer gas is greater. Where the balls are to be steamed and then reused the use of potassium carbonate becomes more feasible. Barium carbonate is also useful.

With the proportions stated the balls remain substantially dry during heat; that is the iron and carbon are present in amounts relative to the alkali, or the cyanid formed from it, sufficient to retain it against liquation. The addition of magnesia in the example given has the same purpose. For the present purposes any substantial flow of alkali or cyanid in the apparatus is not desired. A spherical or ball form of the shaped masses renders their use convenient for feeding through conduits against a counterflow of gas.

Instead of using producer gas of an initial high temperature, ordinary low temperature producer gas can of course be superheated in the ordinary checkers, recuperators, etc., and then used.

lVhat I claim is 1. The process of making 'a high grade improved producer gas which comprises forming producer gas at a temperature sufiicient to slag ash components of the fuel used, taking the gas at the temperature of formation and passing it in contact with a charge of shaped pervious masses of alkali carbonate, iron and carbon containing a relatively small proportion of carbonate, and collecting the cooled improved gas formed.

2. In the manufacture of rich gas and cyanids, the process which comprises pass ing producer gas of a temperature over 1000 G. into contact with shaped masses of carbon, sodium carbonate and iron, the proportion of carbonate being small relative to that of the carbon and iron and collecting the enriched gas formed.

3. In the manufacture of cyanids and enriched gas, by the contact of hot producer gas with shaped masses containing iron, coke andsoda, the process of utilizing exhausted masses of such material which comprises charging the same with the fuel used for making said producer gas.

4. In the manufacture of cyanids and encarbonate, iron and carbon with a relatively riched gas, with the aid of hot producer gas, small proportion of carbonate, and collectthe process which comprises producing high ing the cooled improved gas formed. 1 temperature producer gas of the nature of In testimony whereof, I affix my signature 5 that existing in the hot zone of a blast furhereto.

nace, passing such gas in contact With a charge of shaped pervious masses of alkali R. FRANCHOT.