US1763712A - Process of making calcium molybdate - Google Patents

Description

Patented June 17, 1930 ALAN KISSOCK, or roans'r mas, NEW Yon:

PROCESS OF MAKING CALCIUM HOLYBIDATE No Drawing.

The invention relates to a novel and useful process for producing calcium molybdate, such for example as is used as an addition agent in the manufacture of alloy iron or steel.

Certain objects and advantages of the invention are set forth hereinafter, and others will be apparent herefrom to those skilled in the art, or may be ascertained by practicing the invention. The invention conslsts in the novel steps, sequences of steps, and processes hereinafter described. I By my invention I produce calcium molybdate, suitable for an addition agent in the manufacture of alloy iron and steel, from commercially-available materials by primary elimination of deleterious agents oringredlents, such as sulfur, and subsequent reaction of a molybdenum oxide with an oxide of calcium. I preferably effect .this primary purification as a step in a continuous process comprising the production of the molybdenum oxide from an ore or ore concentrate and the subsequent production of the calcium molybdate as a final. product of the process. This latter feature, however, is optional in so far as concerns the broader aspects of the invention.

The usual or commercially available sources more than one per cent of the mineral. Such ores are usuallyconverted, as by the wellknownflotation process, into a concentrate carrying approximately eighty or ninety per cent of molybdenum sulfide. This concentrate is'the usual starting point for the manufacture of any of the marketable forms of molybdenum, such for instance as the calcium of molybdenum-bearing ores seldom carry copper, etc.- The first step in the process of Application filed November '6, 1926. Serial No. 146,849.

manufacture involves a concentration of the crude and usually low-grade molybdenum sulfide ore into a bi h grade molybdenumsulfide concentrate. 11 the concentration of the crude molybdenum sulfide ore, ordinarily percentages of the impurities above men- M tioned.

Since this is true, a commercially satisfactory process of making calcium molybdate from molybdenum sulfide concentrates must be capable of being carried out even though such minor amounts of impurities be re-. tained.

These impurities often result in the production of a final calcium molybdate contain ing an amount of sulfur suflicient to prevent the use of the calcium molybdate in the production of high grade alloy steels, whereas I have found that if the oxidation of the molybdenum sulfide is substantially completed prior to the introduction of the calcium an oxide, hydroxide, or carbonate, these impurities do not interfere with the production of a substantially sulfur-free calcium molybdate and without any appreciable loss of molybdenum.

As is well known, sulfur is detrimental to the manufacture of high-grade iron and steel, and the elimination thereof during the process of conversion of the raw material is not only usually desirable, but in many cases is absolutely necessary. Accordingly, my invention, in certain aspects thereof, is directed toward effecting the simple, eflicient and economical elimination of the sulfur from the concentrates prior to the formation of the and is entirely driven off, and the purified concentrate is thereafter converted gradually into molybdenum trioxide. By intermixing' calcium oxide with the molybdenum trioxide, and applying suflicient heat, calcium mo- 1 bdate may be produced according to the ollowing reaction M00, Ca() =CaMoO libdenite, namely after the elimination of jlime become thoroughly mixed in the fur sulfur, calcium hydrate is fed into the roasting furnace at a rate which synchronizes with the feed of the molybdenum sulfide, and in such quantity that the ratio of calcium oxide to molybdenum-trioxide is substantially as 1:2.57, which satisfies the formula CaMoO and the reaction already stated.-

{After the oxide of molybdenum and the nace, the temperature is raised sufiiciently to bring about the desired reaction, the temperature being usually raised in practice to approximately 1400 F. at which point the union becomes complete, and the resulting calcium molybdate is delivered directly from the ore roasting furnace.

In commercial work my process may be satisfactorily carried on by usin a multiple hearth ore roasting furnace. prefera ly employ a gravity operating furnace'of this type. In that case the calcium hydrate is fed into one of the lower hearths, prior to which the sulfur has been entirel driven 0E. The feeding mechanism has pre erabl variable speed control to regulate the eedin speed of the calcium hydrate. Additiona heating means are provided; when required, to raise the temperature sufiiciently to cause the materials on the hearths to react to produce the calcium molybdate as the final.

product of the continuous furnacing opera-. tion. 1 Bymy process calcium molybdate substantially free from sulfur is produced with less difiiculty, greater eficiency and more economy than by the processes heretofore in use. It will be understood that the procedure and practice in carrying out' my invention me. be varied, and in some respect quite an el from the'preferred manner of per- 1,7es,712 I r date which comprises roasting molybdenum v sulfide to produce molybdenum trioxide and mixing calcium oxide with the molybdenum trioxide and applying additionalheat thereto to cause them to combine to cium molybdate.

2. The rocess of making calcium molybdate which comprises roasting moylbdenum sulfide'to roduce molybdenum trioxide and mixing calcium oxide with the molybdenum trioxide and applying additional heat to a temperature of approximately 1400 degrees Fahrenheit thereto to cause them to combine to produce calcium molybdate.

3. The process of making calcium molybdatewhich comprises oxidizing molybdenum sulfide to molybdenumtrioxide and as a step subse uent to the elimination of the sulfur applying additional heat and effecting a reaction of the molybdenum trioxide with calcium oxide to produce calcium molybdate.

,4. The process of making calcium molybdate which comprises oxidizing molybdenum sulfide to molybdenum trioxide and as a step subsequent-to the elimination of the sulfur produce calraisin the temperature to ap roximately 1400 degrees Fahrenheit and e ecting a reaction of themolybdenum trioxide with calcium oxide to produce calcium molybdate.

' 5. The process of making calcium molybdate which comprises progressing molybdenum sulfide through a roasting furnace to convert it to molybdenum trioxide, and at a point after the molybdenum sulfide has been completely converted to molybdenum trioxide feeding in a calcium oxide at a proportional rate, and efiecting a reaction to produce calcium molybdate as the final product of the furnacing operation.

6. The rocess of making calcium molybdate whic comprises progressing molybdenum sulfide through a roastin furnace to convert it to molybdenum trioxide, and at a point after the molybdenum sulfide has been com letely converted to molybdenum trioxide fee ng in a calcium oxide at a roportional rate, and applying additional eat thereto and effecting a reaction to roduce' calcium molybdate as the final p not of the furnacing operation.

7. The rocess of making calcium molybdate whic comprises progressing molybdenum sulfide through a roasting furnace to convert it to molybdenumtrioxide, and at a point after the molybdenum sulfide has been completely converted to molybdenum trioxide feeding in a calcium oxide at a proportional rate, and raising the heat of the furnace to approximately 1400 degrees Fahrenheit and efiecting a reaction to produce calcium molybdate as the final product of the furnacing operation.

8. The process of producing calcium molybdate which comprises oxidizing molybdenum sulphide to molybdenum trioxlde, combining a compound containing calcium oxide available by heating with the molybdenum trioxide after the sulphur has been eliminated and effecting a reaction between the molybdenum trioxide and calcium compound to produce calcium molybdate while maintaining the mixture in the dry state. i

9. The process of producing calcium moylbdate which comprises roastmg molybdenum sulphide to produce molybdenum trioxide, combining calcium oxide with the molybdenum trioxide after the sulphur has been elimi- ,nated and efiecting a reaction between the molybdenum trioxide and calcium oxide to produce calcium molybdate while maintaining the mixture in the dry state.

10. The process of producing calcium' molybdate which comprises roasting molybdenum sulphide to produce molybdenum trioxide, introducing and thoroughly intermixing an oxide of calcium with the furnace contents subsequent to the elimination of the sulphur, and effecting a reaction between the molybdenum trioxide and the calcium oxide in the'roasting furnace to produce calcium molybdate. I 11. The. .process of producing calcium molybdate which comprises roasting molybdenum sulphide to produce molybdenum trioxide, introducing a compound containing calcium oxide available by heating into the furnacesubsequent-to the elimination of the sulphur, thoroughly intermixing the molvbdenum-trioxide and the calcium compoun to prevent sublimation of the molybdenum trioxide, and adding heat to the mixture to produce calcium molybdate.

12. The process of producing calcium molybdate, consisting in roasting molybdenite, mixing the roasted product with lime,

and calcining the mixture.

In testimony whereof, I- have signed my name to this specification.

ALAN KISSOGK.