|Title of Invention||
"PROCESS FOR THE PREPARATION OF POTASSIUM BISULPHATE CRYSTAL"
|Abstract||A process for preparation of potassium bisulphate crystal on o o reaction with potassium salts and sulphuric acid at 150 -200 C o o and crystallization of the above product on cooling at 0 -30 C with the recovery of the acid produced in the reaction and recycling the mother liquor to the original crystalizer to obtain Maximum yield of the desired product.|
|Full Text||FIELD OF INVENTIOH
The invention relates to a process for preparation of potassium bisulphate crystal from the potassiun particularly of muriate-potassium and potassium-sulphate with the sulphuric acid.
BACKGROUND OF INVENTIOH
Potassium Sulphate, the major from in which muriate of potassium is used in fertiliser, has been known for many years to have agronomic disadvantages when compared with certain other-potassium salts. Thus, currently the sulphate and nirate are widely used on crops such as tobacco, tomatoes and potatoes, especially for those to be used in the production of potato-chips (crisps).
The chloride ion, if allowed to build to sufficiently high levels, is toxic to most plant species, and its elimination is a desirable aim for the fertilizer industry. In arid areas, totally dependant upon irrigation for their water, for example, the build up of chloride ions in the soil, can become a major-factor in producing a reduced crop yield. At such times, major quantities of water are required to flush out the chloride. Such flushing not only wastes large quantities of valuable water, but> at the same time, flushes out necessary fertiliser constituents in the soil.
The major, if not the sole, factor which has caused the continued use of potassium chloride under these circumstances, is the ready availability and consequent low cost of the chloride as compared with other potassium salts.
The most common substitute for potassium chloride is potassium sulphate. This salt exists in various mineral forms in a number of places, but its separation, usually by crystallization techniques, is more complex and more expensive than that for the
It is produced directly as a double sulphate salt alongwith •mangnesium sulphate in the Western U.S.A., but such material, altough not expensive, per se, is low in potassium concertration and hence more costly to transport and store.
For many years, the chloride salt of potassium has been converted into the sulphate by high temperature reaction with sulphuric acid and considerable quantities are manufactured in this way, particularly in Belgium. The major factors restricting farther production by this method are threefold :
1.) The high energy requirement,
2.) The highly corrosive nature of the reactants and by-product hydrogen chloride.
3.) The need for a local market for the hydrogen chloride produced, otherwise, it must be neutralised at considerable cost before it can be discarded.
For many years, varying routes have been described to convert the chloride using calcium sulphate or sodium sulphate, but none has been used commercially upto the present.
Recently, due to the above disadvantages, it is observed that the use of potassium bisulphate is more convenient and safe in respect of soil condition as a fertilizer instead of potassium sulphate. Potassium bisulphate is used as a fertiliser, particularly in corn (it greatly improves the straw of wheat) and tobacco fields, and in the preparation of potash alum. In view of above, an improved method for preparation of potassium bisulphate removing the aforesaid difficulties is the aim of this presentation.
OBJECT OF INVEHTIQH
The object of the invention is to produce pure potassium bisulphate crystal to substitute potassium sulphate used as
The further- object, of the invention is to develop a method for preparation of potassium bisulphate using minimum energy and proper management, of corrosive hydrochloric acid gas.
The further object of the invention is to produce pure crystalline potassium bisulphate with the minimum chloride concentration to save the soil.
STATEMENT OF THE INVEHTIOH
According to the present invention, there is provided a process for preparation of crystalline potassium bisulphate comprising of the following steps :
1.) Reacting the potassium salts with sulphuric acid at
o o 150 C-200 C and distilled the acid produced in the
2.) Cooling the product produced in step 1 to the pre-determined temperature to separate the crystal of potassium bisulphate,
3.) Recovering the crystal by conventional process and dried for preservation.
4.) Recycling the mother liquor obtained from step 3 to step 2 to obtain further product.
5.) Collecting the acid produced in the reaction for other uses.
DESCRIPTION OF THE INVENTION
o Potassium bisulphate, melting point 219 C, separates in rhombic
crystals from a hot solution of potassium salts in concertrated sulphuric acid. It is a bi-product for the preparation of the
nitric acid when potassium nitrate is reacted with sulphuric
o acid at 200 C. Potassium bisulphate can also be obtained on
reaction with potassium chloride with sulphuric acid at
o o 150 C-200 C with the evolution of hydrochloric acid. The
control heating is required in both the above reaction to avoid the production of potassium sulphate.
The molar ratio of the reactants is required 1:1 to achieve the product in pure condition, The un-reacted reactants and the acid produced in the reaction would be separated from the desired product of potassium bisulphate by the usual method adopted for this purpose,
By varying the temperature range for the reaction with potassium
salts and sulphuric acid, it is observed that the best method of
o o performance is around 150 C-160 C. The crystallisation of the
o o product produced after reaction is done at 0 -45 C and more
o o conveniently at 0 -20 C to obtain the maximum yield of the
Different embodiments of the invention are possible to achieve the best method of perfomance and to obtain the pure crystalline product of potassium bisulphate. It will be understood that skilled persons with many modifications, variations and adaptations may carry out the invention into practice without departing from its sprit or exceeding the scope of claims in describing the invention for the purpose of illustation.
1.) A process for preparation of crystalline potassium bisulphate characterized in that :
I) Reacting potassium salts like potassium chloride and potassium nitrate with sulphuric acid at moler ratio
121 and at temperature Of 150° C-200° C followed by
distillation of the acid produced in the reaction.
II) cooling of product produced in step (1) to the predetermined temperature to separate the crystal of potassium bisulphate.
111} Recovering of the crystal by conventional process and dried for preservation.
IV) Recycling the mother liquor obtained -from Step (III) to step (11) to obtain further Potassium bisulphate.
V) Collecting of the acid produced in the reaction for other use.
2.) A process as claimed in claim 1 wherein the reaction
temperature is 150°C-160°C.
3.) A process as claimed in claim 1 wherein the cooling
temperature is 0°C-45°C.
4.) A process as claimed in claim 1 wherein the cooling
temperature is 0°C-20°C.
5.) A process as claimed in clam 1 wherein the Hydrochloric acid or Nitric acid, which is produced during the reaction, is collected by distillation.
6.) A process for preparation of crystalline Potassium bisulphate substantially as herein described.
|Indian Patent Application Number||1102/DEL/2003|
|PG Journal Number||44/2009|
|Date of Filing||03-Sep-2003|
|Name of Patentee||BHUSHAN DHEER|
|Applicant Address||NIMAK WALI GALI, NEAR SHARMA COLONY, OUTSIDE GILWALI GATE, AMRITSAR-143001, PUNJAB, INDIA.|
|PCT International Classification Number||C01D 5/02|
|PCT International Application Number||N/A|
|PCT International Filing date|