US2144328A - Process for treating and purifying sodium chloride - Google Patents

Description

Jan. 17, 1939. L. B. cARRlzo PROCESS FOR TREATING AND PURIFYING SODIUM CHLORIDE Filed Dec. 2, 1935 2 Sheets-Sheet l Jan. 17, 1939.

L. B. CARRIZO PROCESS FOR TREATING AND PURIFYING SODIUM CHLORIDE frwen sflarhibmefiarr Wyn/K Patented Jan. 17, 1939 UNITED STATES PATENT OFFICE PROCESS FOR TREATING AND PURIFYING SODIUM CHLORIDE Luis Bartolom Carrizo, Quilino, Argentina Application December 2, 1935', Serial No. 52,519%

4 Claims. (01. 209-2) it suitable for consumption.

It is known that certain impurities commonly found in salt in its natural state, particularly the magnesium compounds, readily absorb moisture and, when heated, conglomerate in the form of pellets. The process according to the present invention is based upon this hygroscopic quality inherent in said impurities, with the end in view of purifying the sodium chloride. The process may be performed by a special arrangement or means of comparatively simple construction and operation.

By,way of example, the attached drawings show apparatus of a. type suitable for practicing the process of this invention.

In the drawings:

Figure 1 is a front view of a'set of kilns and a sitter used in practicing the process of my invention;

Figure 2 is a sectional view taken substantially on line AB of Figure 1;

same reference numbers indicate the same parts.

The illustrated arrangement. or apparatus for v practicing the process of my invention comprises two similar kilns I. These kilns are preferably formed of brickwork of fireproof material.

1 Each kiln l iscomposed of afurnace 2. and an' ash pit 3 provided with openings 2v and 3 for feeding the kiln and discharging the ashes, re- 45 spectively. These openings, which may be fitted with suitable doors, provide for internal air draught.

As may be observed in Figure 2, a horizontal partition 5 is arranged within the furnace 2 having passage 6 at the back thereof, through which the hot'gases and the combustion smoke are conducted. Passage 6 opens at its upper end into a space or hot chamber 1, between partition 5 and the top wall of the kiln, into which space opens mosphere. On top of the kiln I there is a heating surface 9 surrounded by a low railing or retaining wall ill.

60 Between kilns l a space is left, as maybe seen Figure 3 is a side view of the sifter, on an en In the different figures of the drawingsythe a stack 8 for creating a draft through furnace 2 and space 1, this stack discharging into the atin Figures 1 and 5, which space accommodates the sifting machine, illustrated more fully in Figures 3, 4, 6 and 7.

The sifting machine comprises a hopper II from which troughs l2 extend upward to the tops of the kilns I, adjacent the heating sur-' faces 9 thereof.

Hopper H is arranged on a. scaffold l3 and communicates with the upper end of a casing mounted on thescaifold at an inclination downward and forward thereof, by means of flexible rods J5.

For the purpose of imparting a reciprocating motion to casing I4, I provide a shaft IS on which is secured an eccentric l1 connected by a rod II! to casing l4 beneath the latter. Shaft I6 is journaled in suitable bearings on the scaffold i3 and is provided at one end with a pair of pulleys l9 and 20, -one being fast to the shaft and the other loose thereon, adapted to be driven through an endless belt in connection with a motor (not shown), providing a drive of known type. Any

other suitable means may be provided for rotatmovement may be imparted to the shaft by hand power, by arranging a crank on one end of the shaft, in a known manner which need not be illustrated.

Within thecasing l4 (see Figure 6) there are conveniently arranged a coarse mesh sieve 2i and a fine mesh sieve 22, the latter being placed beneath sieve 2|. If desired,'additional sieves of increasingly finer mesh downward, in accordance with the different degrees of fineness of salt it is desired to obtain, may be provided,- as will be readily understood from the following explanation, and which need not be illustrated.

The sieves 2| and 22 divide the casing it into three compartments or chambers havingat the front thereof, respectively, outlets'23, Hand 25,

the first outlet 23 being for theiimpuritiescommonly termed tailings, the second outlet 24 being for the sodium chloride in small lumps, and

the third outlet 25 being for sodium-chloride in finely powdered form.

The, process in acc rdance with this invention is'asfollowst The crude salt which is extracted from the salines, is first passed through a grinding mill of known type. If the salt is already available in a more or less divided state, grinding may be dispensed with.

In order to expel the moisture and cause the formation of the conglomerates of the impurities contained in the sodium chloride, the crude salt, which has previously been ground, when necessary, is applied to the heating surfaces 9 of the kilns l which surfaces are suitably heated, striving to hold their temperature between 80 and 100 centigrade.

By spreading the salt upon the surfaces 9 and agitating it by means of a rate or any other suitable tool, the water contained therein will be expelled by evaporation, while simultaneously the impurities will absorb a portion of the water and form pellets, by virtue of their hygroscopic character referred to thus forming the tailings. When this operation has been completed, the salt is transferred, conveniently by means of the rakes or other tools, to the troughs l2, and by, the latter, to the hopper I I, whence it passes into the casing ll onto sieve 2 I.

The impurities or tailings which, on account of their conglomeration, will not pass through the sieve 2|, are discharged through the outlet 23, whereas the particles of sodium chloride readily pass through said sieve 2| and fall upon the sieve 22, which is of fine mesh. The more or less coarse grained salt will be discharged through outlet 24, while the salt in finely powdered form, which passes through the fine mesh sieve 22, will be discharged through outlet 25. In order to facilitate the movement of the salt and prevent clogging of the sitter, the casing I4 is reciprocated in the manner previously described.

At the respective outlets 23, 24, and 25, suitable containers may be provided for collecting the materials issuing therefrom. The tailings discharged from outlet 23 may be rejected, and the sodium chloride discharged from outlets 24 and 25 may be suitably packed for transportation and sale.

The sodium chloride is thus collected in almost a chemically pure state, the originally contained impurities having been eflectivelyseparated therefrom by the combined action of heating and agitation, with accompanying conglomeration of the impurities, during the drying process to which the crude salt extracted from the mines is subjected.

' In the following is given, by way of illustration only, an analysis of 100 grams crude salt extracted from Salinas Grandes (Province of Cordoba, Argentine Republic) in order to establish the ingredients forming conglomerations and the quantity of sodium chloride which is obtained:

100 grams crude salt, dfledpcontains Grams Water 0. 00000 Insoluble inorganic matters 0.05760 Insoluble organic matters 0. 4011 Calcium sulphate (CaSO) 0.09977 Magnesium sulphate (MgSO4) 0. 00452 Sodium sulphate (NazSOO 0.47592 Sodium chloride (NaCl) 99. 31242 Nondetermined matter 0.00925 kilns i, forming pellets which are easily separated in the sifting operation, in such manner as to obtain the sodium chloride in a pure state, the particles of foreign substances which succeed in getting past the sieves and mixing with the salt proper forming an infinitesimal quantity which may be disregarded.

Modifications may be introduced without departing from the scope of the present invention, as defined in the appended claims.

I claim:

1. The process of treating a mixture of sodium chloride and hygroscopic impurities for removal of the latter from the sodium chloride, which comprises heating the mixture to a maximum temperature of approximately 100 C. and drying the' sodium chloride by the combined action of heat and absorption of moisture by the hygroscopic impurities whilegconglomerating the latter in the form of pellets, and separating the dried sodium chloride from the pellets of conglomerated impurities.

2. The process of treating a mixture of sodium chloride and hygroscopic impurities for removal of the latter from the sodium chloride, which comprises spreading the mixture in a relatively thin layer upon a heating surface, there heating the mixture to approximately 80 C. while stirring it, thereby drying the sodium chloride by the combined action of heat and absorption of moisture by the hygroscopic impurities while conglomerating the latter in the form of pellets, and separating the dried sodium chloride from the pellets of conglomerated impurities.

3. The process of treating a mixture of sodium chloride and hygroscopic impurities for removal of the latter from thesodium chloride, which comprises spreading the mixture in a relatively thin layer upon a heating surface, there heating the mixture to a temperature of approximately 100 C. while stirring it, thereby drying the sodium chloride by the combined action of heat and absorption of moisture by the hygroscopic impurl ties while conglomerating the latter in the form of pellets, and separating the dried sodium chloride from the pellets of conglomerated impurities.

4. The process of treating a mixture of sodium chloride and hygroscopic impurities for removal of the latter from the sodium chloride, which comprises spreading the mixture is a relatively thin layer upon a heating surface, there heating the mixture to a temperature between approximately 80 and 100 C. while stirring it, thereby drying the sodium chloride by the combined action of heat and absorption of moisture by the hygroscopic impurities while conglomerating the latter in the form of pellets, and separating the dried sodium chloride from the pellets of conglomerated impurities.

t LUIS BARTOLOME CARRIZO.

Images