US1628000A - Process for the manufacture of cement - Google Patents

Description

y 'r. RIGBY PROCESS FOR THE MANUFACTURE OF CEMENT Original Filed July-20, 1925 Patented May 10,1927.

UNITED STATES THOMAS BIGBY, OF LONDON, ENGLAND.

PROCESS FOR THE MANUFACTURE OF CEMENT.

Original application filed July 20, 1925, Serial N'o. 44,865, and. in Great Britain July 28, 1924. Divided 'and this application filed November 28, 1925. Serial No. 71,923.

This application is a division of application 44,865 filed July 20, 1925.

This invention is concerned with cementmaking by the wet method in rotary kilns by atomizing or similarly dispersing the cement slurry in a finely divided condition in the gases in the kiln so that these latter shall exert a drying action upon and be somewhat cooled by the slurry before it is collected on the internal wall of the kiln.

I have found in practice that when sup plying slurry to a kiln in an atomized (ondition it is Well'to take account of the substantial capacity which the gases may in some cases have to carry dispersed slurry in suspension in them out. ofthe kiln especially where the dispersal is caused to occur only just inside the mouth of the kiln or where the kiln is being forced to a high output. Again regard may" with advantage be paid in some cases to the possibility of utilizing the residual heat of the gases leaving the kiln for although unusual cooling of the gases is to be expected by dispersing the slurry in the kiln gases in the kiln yet the recovery of suspended matter from the gases and of the residual heat of the gases (whether large or small) is apt to be a matter of substantial economic advantage.

Important features of the invention con- (ern themselves with these conditions where they present themselves in making cement by atomizing or similarly dispersing slurry into the rotary kiln. p

In accordance with oneof these features space afforded by the kiln head itself is utilized to bring the gases therein into contact with slurry that'receives cement material carried out of the. kiln by the gases and acts as a convenient vehicle for its removal from out of the gas passages. J

The above and other features of the invention will become fully evident to those skilled in the'art from the following description with reference to the accompanying drawing of one form of cement making plant and method illustrative of the invention.

The accompanying drawing shows in sec- 7 tional side elevation the general arrangement of one form of installation forcarrying out a process according to the invention.

The upper end of the kiln is shown at 3 opening intothe kiln head through the rear wall 5 of which slurry sprayi nozzles 7 and 8 areshown-as operating. T ese project the spray into the kiln through the gas space 9 of the kiln head.

It may happen, especially when the kiln is forced and an unduly high rate of output is sought after, that there arises a tendency for partly dried material to be carried out of the kiln by the gases. This may tend to block up the smoke chamber in the kiln in time if not attended to especially as such material may in a-partly dried and sticky condition settle in this chamber and be difficult to remove apart from the inconveniente involved in providing for this purpose opportunities of access to this chamber.

Such inconveniences may be overcome by providing for the gases meeting a liquid inv this smoke chamber in which suspended material is deposited. For; example, the base of the smoke chamber may have in it or act as a container for water or slurry and if such container be equipped with means for agitating the liquid the deposited matter is easily stirred more or less homogeneously into the contents of the container and withdrawn readily with the liquid.

In the drawing the kiln head is shown as converted into a reservoir for slurry over which the gases from the kiln are caused to ass in flowing down between the rear wall 5 of the head and the front wall 35 ofthe' latter and up behind the wall 5 and over the wall 37 away to the chimney, this slurry (which is fed in through an inlet 33) being kept stirred by compressed air from pipes indicated at 39 and withdrawn from a well 41 outside the kiln head and into which. well the slurry passes through an opening 43 beand well.

Where in a case as referred to slurry for the spraying nozzles 7, 8, of the kilnis used as the liquid to catch the deposits this obviously becomes advantageously concentrated before being passed to the kiln by the matter deposited in it. If water or weak slurry is used and it does not by the admixture with it of deposited matter reach a condition which fits it forsupply, if desired, to the kiln it may be used in the slurry making installation of the plant so thatits contents of cement materials shall not be wasted. Such an exposure of the gases to a liquid in passing from the kiln to the chimneywill low the levels of the liquid in the reservoir in use in cement plants but even if it does not in this way avoid losses of cement materials that are inevitable'to-day it will at all events facilitate dealing with what is caught from the gases since the dry dust usually caught is troublesome to collect and transport to where it can be made use of.

' The exposure of the gases to a liquid in the kiln head as described will inevitablybe accompanied by some cooling of the gases and evaporation of water which in the case viding the kiln head instead ofor in addition to a container for liquid ashas been above mentioned, with suitable slurry atom-.

izing or like dispersing means such for example as one or more slurry spraying nozzles directing a spray or sprays down the kiln head from, and it may be through, one or more openings in the kiln head at or near its top.

In any case such as described where the gases from the kiln are cleansedor cooled y (or material carried out of the kiln by the gases is caught in liquid such for instance as slurry the liquid may, either be passed through the gas contact space and forthwith utilized as desired or it may be continuously withdrawn from the said space and returned to it anew, only a portion of the circulating liquid being continuously or from time to time withdrawn for use as desired and this loss made good by the addition of fresh liquid to the circulating bulk. Any slurry enriched from the gases by material carried out of the kiln'thereby should be very thoroughly mixed before being passed to the spraying devices of the kiln and accordingly it may be desirable after any such slurry is withdrawn from thedevice in which it is exposed to the gases-from vices.

liquid container will be arranged entirely and it may in some cases be advantageous to arrange that the container for liquid which. collects the material carried out of "the kiln by the gases is partly in the kiln head and partly-outside the head-to facilitate provision of stirring and mixing -de- It may be in some cases that the outside the kiln head in which case arran ement will preferably be made by suita le conveying means such as a travelling band or bands for example in the floor of the kiln head to take deposited material from the kiln head into the liquid container'which liquid then becomes a vehicle for the'expeditious removal of the deposited material.

Such an arrangement would be advantaw, geous in cases where extensive mixing or grinding is required asoopen inspection of the mixture is thus facilitated and usually the container will be arranged as nearly adjacent to the kiln head as is possible.

What I claim as my invention and desire to secure by Letters Patent is In a wet process of making cement in a heated rotary kiln having a head at the gas exit end thereof and a chamber immediately beneath and in communication with said gas exit end, the step of immediately passing the hot "gases, carrying solid particles from the kiln, upon their exit therefrom, over a body of slurry in said chamber, whereby theheaviest particles of any material swept out of .the kiln fall-by gravity and are entrained by the slurry in sai chamber in the kiln head.

In test'mony whereof I aflix my signature.

. THOMAS RIGBY.

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