DE2148601C3 - Process for processing tachhydrite - Google Patents

Description

It is known to remove mineral salts from their deposits by brining them out with water or dilute salt solutions to bring them to light and work through these solutions there. The solubilization of sylvinite, hard salt or Carnallite deposits cause difficulties insofar as the promoted solutions contain the salts only in contain relatively low concentration, moreover, during continuous operation do not remain constant due to the changing composition of the deposit.

The subject of DL-PS 53 054 is a process for the production of potassium chloride and magnesium chloride by leaching out of carnallite deposits, after the carnallite by a corresponding to the temperature composite alkali containing magnesium, potassium and sodium chloride completely dissolved and this solution is finally evaporated and cooled to obtain the carnallite. The here and the subsequent processing of the obtained carnallite resulting solutions are in appropriate Proportions mixed, and this mixture is used again as a dissolving solution for recovery.

The FR-PS 10 50 770 describes a process for the production of magnesium and potassium salts from Solutions containing the chlorides and sulphates of magnesium and potassium. This solution comes with mixed with a carnallite lye, which is saturated in magnesium chloride, until kainite crystallizes out, the is separated. Then the solution is evaporated to saturation with bishofite, whereupon sodium chloride is derived from it and kieserite crystallize, which are also separated off. Then the remaining The solution was further evaporated and the magnesium chloride obtained as a solid was partially removed from the mother liquor deposited and the remainder together with the mother liquor in the initial stage of the process for Kainite education used.

The method described below, on the other hand, concerns the task of using natural tachhydrite Aussolen Bischofit to win, also just by

ίο taking advantage of the different solubilities of the the resulting salts and double salts must be dissolved.

A method for processing tachhydrite in connection with the brining out of underground carnallite deposits containing tachhydrite has been found. After that, water is first introduced into the deposit via a borehole and left in the deposit until the solution is saturated in bishofite, whereupon the solution, which is essentially saturated in bishofite, carnallite and sodium chloride, is brought to the surface through a production borehole and then up to A synthetic tachhydrite is added to saturation, a decomposition bishofite being formed and separated from the solution; The solution freed from the decomposition bishofite is then evaporated and _{cooled to saturation with tachhydrite, CaCl 2} -4H ₂ O and sodium chloride, the synthetic tachhydrite introduced into the solution produced from the production well being formed and the remaining residual solution being repelled.

The water is advantageously introduced into the deposit at a temperature of up to 35 ^{° C.}

It can also be beneficial to add synthetic tachhydrite to the solution extracted at about 35 ° C move or the solution freed from the decomposition bishop after evaporation to about 35 ° C to cool off.

The method of the invention is explained, for example, by the phase diagram shown in the figures. The KCL, MgCl ₂ and CaCl ₂ axes form a right-angled three-dimensional coordinate system. The dashed lines mean the coordinates of the points in space. The solid thin lines (three-salt lines) show the composition of the solutions (equilibrium solutions) that are saturated at 35 ° C on three sediments. These are the soil bodies entered in the fields emanating from the lines on both sides and are stable in these fields, and sodium chloride, which occurs as a stable soil body in all fields. In the contact points of three lines, therefore, four bodies of soil including sodium chloride are stable. The dotted coordinates define the points a, b and c in space.

A tachhydrite deposit of roughly the following composition

Tachhydrite

Carnallite

NaCl

Non-chloridic

Components

Weight - 90
5

results in 8.94 t of water at a temperature of 35 ° C if this is introduced through a borehole and the The solution is left in the deposit at 35 ° C until the bishopite saturation is reached, the following

Bischofite, carnallite and sodium chloride practically saturated solution (point a) of the composition:

7.86 t MgCl ₂ +4.6 t CaCl ₂ + 0.068 t KCl

+0.084 t N aCl + \ 8.0 t H ₂ O,

which is to be produced through another borehole.

With this amount of solution, 10.50 t of the synthetic tachhydrite resulting from the process become the following Composition:

10.50 12MgCl ₂ CaCl ₂ 12H ₂ O + 0.037 t NaCl

decomposed at 35 ° C. 15.50 tons of decomposition bishofite are produced the following composition:

15.50 t MgCl ₂ • 6H ₂ O + 0.058 t KCl • MgCl ₂ • 6H ₂ O

+ 0.055 t NaCl ' ⁵

and one at 35 ° C on bishopite, tachhydrite, carnallite and NaCl saturated decomposition solution of the following composition (point b):

4.44 t MgCl ₂ + 6.90 t CaCl ₂ + 0.053 t KCl

+ 0.067 t NaCl + 14.00 t H ₂ O.

4.65 t of water are removed from the decomposition solution in a known evaporator. The remaining solution is cooled to 35 ° C. and becomes saturated with tachhydrite, CaCl ₂ -4H ₂ O and NaCl (point c). 10.50 t of synthetic tachhydrite crystallize and is fed back into the process. A final liquor of the following composition remains to be rejected:

0.64 t MgCl ₂ +4.50 t CaCl ₂ + 0.053 t KCl

+ 0.029 t NaCl + 4.94 t H ₂ O.

The evaporation of the decomposition liquor is driven so far that, after cooling to 35 ° C, it is simultaneously _{saturated in tachhydrite, CaCl 2} -4H ₂ O and NaCl, whereby as much synthetic tachhydrite is formed as for decomposition with the formation of one of bischofite and tachhydrite saturated decomposition liquor is required. The process of the invention thus uses the knowledge that such an amount of magnesium chloride is circulated which is sufficient to maintain practically the tachhydrite and bishopite saturation side by side (point b) in the decomposition liquor.

The method of the invention offers the advantage that the bishopric production with little specific Water vapor (0.3 t water vapor per t recovered Bischofite) and with a magnesium chloride yield of 90%, based on the total amount of magnesium chloride produced.

1 sheet of drawings

Claims (4)

Patent claims: 1. A method for processing tachhydrite in connection with the brining out of underground, tachhydrite-containing carnallite deposits, characterized in that water is first introduced into the deposit via a borehole and left in the deposit until the solution becomes saturated with bishopite comprises that then the solution, which is essentially saturated with bishofite, carnallite and sodium chloride, is brought to the surface through a production well and then a synthetic tachhydrite is added to saturation, a decomposition bishofite being formed and separated from the solution, and that the The solution freed from the decomposition bishopric is then evaporated and _{cooled to saturation with tachhydrite, CaCl 2} -4H ₂ O and sodium chloride, the synthetic tachhydrite introduced into the solution produced from the production well being formed and the remaining residual solution being repelled. 2. The method according to claim 1, characterized in that the water at a temperature up to is introduced into the deposit at 35 ° C. 3. The method according to claims 1 and 2, characterized in that the promoted to days The synthetic tachhydrite is added to the solution at around 35 ° C. 4. The method according to claims 1 to 3, characterized in that that of the decomposition bishofite freed solution is cooled to about 35 ° C. after evaporation.