US1977208A - Process of sulphating titaniferous ores - Google Patents

Description

Och 16, 1934- B. DqsAKLATwALLA ET AL 1,977,208

PROCESS SULPHATING TITANIFEROUS ORES Filed Aug. 8, 1952 4 Sheets-Sheet l INVENTORJ Q SJW, SMX

Oct. 16, 1934. B'. Dt sAKL'ArwALLA Er AL 4 PROCESS OF SULP-HATING TITANIFEROUS `GRES Filedv Aug. 8. 1952 4 Sheets-Sheet 2 IUNNWV l l l l- 1| n-- wIIJwIJ wNM. Vkrflkzrzil NNI NQ PROCESS OF SULPHATING TI'I-ANIFEROS ORES Filed Aug.) 8,` 1932 4A Sheets-Sheet 3 B. D. sAKLATwALLA ET Al. 1,977,208

Oct. 16, 1934. B. D. sAKLA'rwALLA Er AL 1,977,208

` i I PROCESS oF SULPHA'IING TITANIFEROUS oREs Filed Aug. 8,' 1952 4 Sheets-Sheet 4 l :.Nv Nions l www M Luz atented Oct. 16, l93t PROCESS @E SULlPgNG TITER'U Byramji lli. Salxlatwalla and Halbert Earl Dunn, Grafton, Pa., and Albert E. Marshall, Scarsdalle,J N. Y., assignors to Southern Mineral Products lilorporation, New York, hl. il., a corporation of Delaware Application August 8, 1932, Serial No. 627,934

` 2 lillaims. (Gl. 'I5-la) The present invention relates to a process of sulphating titaniferous ores.

The most common titaniferous ore is ilmenite,

which is ordinarily regarded as a ferrous titanate 5 in which the iron and titanium oxides are very strongly chemically combined with each other.

This ore is very refractory to the action of acids or other chemicalv agents. Other common titaniferous ores are rutile and magnetites carrylll ing high percentages of titanium oxide. These l ores are used as the raw material for the manufacture of titanium oxide which has a wide use for pigments, etc. In the usual sulphuric acid proc-.-

ess oi7 making titanium dioxide from a titanifer' il@ ous ore such as ilmenite, the first step consists in subjecting the ground ore to strong sulphuric acid to convert the titanium and iron contents of the ore into soluble titanium sulphates and soluble iron sulphates. The sulphuric acid is usually strong acid containing 80% or more sulphuric acid content. When the sulphuric acid is added 'to the ground ore, the mixture during the acid reaction tends to formfa hard cake. This cake has a tendency to coat the particles of the ore and thus slow up the action of the acid on the ore particles. The usual agitating and stirring devices are not emcient to remove this coating of cake continuously from the particles ofthe ore, and consequently under such conditions the reaction not only proceeds at a slow rate, but is never carried to a high degree of completion.

In our process the mixture of ore and acid is thoroughly kneaded during the acid reaction at tack, so that the particles of the ore are maintained in a loose condition. The kneading causes an attrition of the particles over each other, thus continuously exposing kfresh surfaces of the ore particles to the acid attack. 'I'his results in speeding up the rate of the acid reaction, and as 40 this reaction is of an exothermic nature the heat evolved from the reaction is very much more effectively used in raising the temperature of the mass than would be the case if the reaction proceeded at a slower rate. Further, owing to the continual removal of the cake from the ore par- 'ticles, the reaction is completed to a very much greater degree so that very little, if any, of the unattacked ilmenite remains in the reaction ves-` Figure 3 is a vertical section along the line meslH of Figure 2;;

Figure l is a top plan view of the kneading tub and blades;

Figure 5 is a section along the line V-V of Fig- @il ure d; and

Figure 6 is a side view of one of the kneading blades.

In the illustrated embodiment of the kneading machine, reference numeral 2 indicates the @5 mixing or kneading tub in which the ore and acid are thoroughly stirred and kneaded by means of mim'ng and kneading blades 4or arms 3 and d. The shape of the kneading blades 3 andfl is illustrated in Figures d, 5 and 6. The tub 2 has a cenlill tral ridge 5 along its bottom forming two rounded bottom portions in which the kneading blades 3 and i rotate. 'I'he action of the kneading blades is similar to that of a bread dough kneader. They p serve to not only mix the slurry of acid and ore 'lt charged into the machine, but also to thoroughly `knead the'mixtureafter the acid attack has pro.

gressed, breaking up any lumps and ycausing a thorough attrition of the particles of the stiff mass, so as to expose fresh surfaces of the ore par- GCD ticles to the acid attack.

The tub 2 has an oil jacket 6 arranged to be iilled with hot oil supplied through a hot oil circulating system 'l from 'an external oil heater. The tub is surrounded by' a heat insulating jack- 85 et 6a which serves to prevent loss of heat. ,Y

Thev tub has a cover 8 having a feed inlet. connection 9 through which the acid and ore are supplied to the mixing tub, and an exhaust vent 10 through which* the acid fumes may be drawn 90 away- The mechanism for driving the kneading'blades- 3 and 4 is as follows: 'I'he drive for rotating the kneader blades is froin` a motor 11 through a sprocketchain drive 12 for driving the shaft 13. -95 The shaft 13 extends lengthwise of the machine and is arranged to transmit power for driving the kneading blades 3 and 4 from both ends of the machine. .'I'he gearing connecting the shaft 13 to the kneading blades 3 and 4 is the same at 10o both ends of the machine, so that only the gearing connection at one end of the machine need be described. The shaft 13 carries a pinion 14 which drives a'gear 15 on a short shaft 16. A

vpinion 1'1 on the shaft 1s drives a larggear 1a 105 ing blades 3 and 4, respectively. The kneading v blades 3 and 4' rotate in the same direction as 11G.

indicated by the arrows, so as to give theproper mixing and kneading action.

l The tub 2 is mounted between end housings 25 which enclose the gearing connections above described. The tub 2 is mounted to turn in housings on the axis of the shaft 19, thus permitting the turning while the gears 21 and 22 of the kneading v l Per centl Feo l v 36.00 F6201 14.00

arms are in mesh with the gear 20. The shafts of the gears 20, 21 and 22 are jpurnaled in apivoted bearing casting 26 which is secured to the ends of the tub and which casting carries a segment of a worm wheel 27. This segmentis meshed with a worm 28 on a shaft 29. The shaft 29 carries a worm wheel 30 which is driven by a worm 31 on a shaft 32. The worm 31 is lubricated by a gear 31 dipping in an oil well 31h. The shaft 32 is driven through bevel gearing 33 from a motor 34. Suitable control mechanism for the motor 34 governs and limits the .tilting of the tub to discharge the contents after the kneading operation.

The following is a typical example of treatment of an ilmenite ore according to our process.

Thelparticular ore in question has had approxi-7- stirredar agitated.

mately'the following analysis:

The ilmenite ore was ground to a iine granular condition. A charge of 500 pounds of the ground ore and 1200 pounds of 80% sulphiic acid was fed together into Ythe kneading machine, the blades 3-and 4 beingcontinuously operated. The sulphuric acid was preheated to about 150 F. The ore was used cold. The oil in the heatingjacket :'6 was maintained at about-175 F. After the change of ore and acid was fed in, the cover -8 was placed over the kneading machine. About ten to twentyminutes were required for heating the charge and initiating the acid attack. This constituted the rst stage of the operation. 'This was followed by the second stage of the operation which required about seven to twelve minutes. During the second stage of the operation a violent reaction took placebetween the ore and sulphuric acid, resulting in the evolution of large volumes of water vapor and amarked increase in tem` perature due to the exothermic reaction between the acidand the ore. It requires a temperature ofv about 300 F. to start the rapid attack of the acid upon the ore. As soon as the rapid attack begins, its exothermic reaction raises the temperature of the mass still further. The reaction apparently takes place best at these elevated tem'- peratures and it is therefore of advantage to carry the reaction to completion as soon as possible before the exothermic heat of reaction can be dissipated.

At the beginning of the rapidacid attack ,the

mass is in -the nature of a rather thin slurry.

This thickens gradually as the reaction proceeds until at the end of the violet reaction it is in` 'stitutes the third stage of the'operation. During this third stage of the operation the mass is sub- :lected to a thorough baking due to the residual exothermic heat of the reaction and also to the heat supplied by the hot oil jacket 6. The -baklng and kneading ofthe massis carried to a point where the batch is no longer sticky'bu't will crumble ylike sand. At the end of the third or baking stage,the `kneading machine is tilted and 80 the mass is dumped toa car to be transferred to the usual dissolver or tank in which the' sulphated ore is mixed with waterl to bring ,the titanium and iron sulphates into water solution. This water solution of the titanium and iron sulphates is then treated in any of the usual ways for the recovery of the titanium dioxide.

'Ihe quantity of acid used is determinedby analysis of the ore, the-amount of acid charged being that which is theoretically required to convert all of th e metallic oxides present into sul- -phatesplus about 5 to 10% excess. While the conversion is never quite complete, .the yield of sulphates is carried toa h igh point, varying from about 90 to 95%. This is a greater yield than in 95 the prior processes in Whichinstead .of kneading th'e mass, the ore and sulphuric acid are merely During the first stage of the operation theA kneading machine maintains the mass as a iluidz readily stirrable slurry. As the second stage of the operation' progresses, the titanium and iron sulphates tend to form hard coatings upon the par'- ticles of the ore. -These-sulphatesare not soluble in the strong sulphuric acid. They therefore tend .105 to form-insoluble envelopes preventing further at'- tack of the acid upon the'e'nclosed ore particles. They alsotend to cement the .particles together into a hard conglomerate or cake. By the continued kneading action of arms 3 and 4 on theillo machine, the formation of a hard "cake is prevented .and-the mass is maintained in a loose granular condition as it tends to stiil'en and become more solid during the sulphatizrlng reaction.

Also, as above noted, thekneading causes an atthe .continued kneading of the materiaLthe rel action takes places rapidly and allows maximum utilization of the exothermic heat generated during the second stage, the high temperature of which in turn tends tofurther speed the reaction and give a maximum recovery. 1 As stated previously, the kneading action employed in the present process is similar to the action of kneading dough ina bread dough kneader. It is vdistinguished from the usual mixing, agitating or stirring whichhave been used previously in the treatment of titaniferous oresv with sulphuric acid. by the fouowing characteristics: 'I'he kneading 'action maintains all of the mass in a state of constant agitationfnot permitting any of it to lie in dead spaces, so that it is'140 unattacked bythe acid. 'I'he plastic mass is thrownfrom one blade'to the`other`so that a squeezing and pulling action is exerted on the mass by the motion of the blades againstv the trough walls, the saddle in the bottom of the trough, and between the blades themselves. 'Ihe blades have an interweaving action which tends to clean them by shearing away any adhering mass as the blades reach their point of closest proximity. These characteristics of the kneading' 150 action result in increased conversion of the titanium dioxide content of the titanium ore. We have found that when ilmenite ore and sulphuric acid are stirred in apparatus previously employed in this art, not more than to 80% of the titanium dioxide content can be converted to water soluble titanium sulphate, whereas by the kneading action described herein, to 95% soluble sulphate can be obtained.

While we have described one particular -example of carrying out oui` process and have shown a kneading machine which we have found satis7 factory to use, it is to be understood that the invention is not limited to the use of the particular kneading machine illustrated or to the specic procedure set forth in the typical example, but that the invention may be otherwise embodied and practiced in the sulphating of titaniferous ores within the scope of the following claims.

1. The process of sulphating titaniferous ores, which comprises thoroughly kneading a plastic doughy mass of ground ore and sulphuric acid during the period of acid attack upon the ore, said kneading being substantially identical with that obtainable by 'kneading said plastic mass in a mixer of the type having walls forming a trough and a saddle in the bottom of the trough and inter-acting blades of a Z or so-called sigma pattern, and characterized by intensive knead-v ing, squeezing and pulling o'f the mass against the trough walls, the saddle, and between the blades themselves.

2. The process of sulphating titaniferous ores, which comprises kneading a mass of ground ore and strong sulphuric acid while subjecting the mass to external heat until the reaction between the acid and ore is initiated, thoroughly kneading the resultant plastic' doughy mass to maintain it in a loose granular condition, said knead'- ing being substantially identical with that obtainable by kneading said plastic mass in a mixer of the type having walls forming a trough and a saddle in the bottom of the trough and interacting blades of a Z or so-called sigma pattern, and characterized by intensive kneading, squeezwalls, thev saddle, and between the blades themselves, and continuing the kneading of the mass after the primary reaction has occurred while subjecting it to continued application of external heat to bake the mass and further carry the reaction to substantial completion.'

BYRAMJI D. SAKLATWALLA.

HOLBERT EARL DUNN.

ALBERT E. MARSHALL.

ling and pulling of the mixture against the trough l

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