Potas­si­um salts. Gen­e­sis, char­ac­ter­is­tics and prospects for extrac­tion

Potas­si­um salts are strate­gi­cal­ly impor­tant min­er­als that are wide­ly used in agri­cul­ture, chem­i­cal and met­al­lur­gi­cal indus­tries. In Ukraine, potash salt deposits were formed as a result of sed­i­men­ta­ry process­es in Neo­gene and Per­mi­an salt-bear­ing basins, which are char­ac­terised by a com­plex struc­ture and diverse min­er­al com­po­si­tion.

Potash salt is includ­ed in the list of min­er­als of nation­al impor­tance approved by Res­o­lu­tion of the Cab­i­net of Min­is­ters of Ukraine No. 827 of 12 Decem­ber 1994 as a chem­i­cal and agro­chem­i­cal raw mate­r­i­al.

Physical and chemical characteristics

The phys­i­cal and mechan­i­cal prop­er­ties of potash salts depend on their min­er­al com­po­si­tion and struc­ture. The main min­er­als are sylvite, car­nal­lite, kai­nite, lang­bei­nite, poly­halite and halite. They have an aver­age den­si­ty of 2.0–2.5 g/cm³, high sol­u­bil­i­ty in water and sig­nif­i­cant com­pres­sive strength, which allows them to be mined at depths of up to 1000 m. How­ev­er, the pres­ence of impu­ri­ties such as anhy­drite, kieserite or clayey mate­ri­als can sig­nif­i­cant­ly affect the mechan­i­cal prop­er­ties of the rocks.

There are three types of potash salts based on their chem­i­cal com­po­si­tion:

• Chlo­ride (sul­phate-free) – rep­re­sent­ed by sylvi­nite and car­nal­lite.
• Sul­phate (sul­phuric acid) – dom­i­nat­ed by min­er­als such as kai­nite, lang­bei­nite, poly­halite and shen­ite.
• Mixed sul­phuric acid-chlo­ride salts.

Genesis of potassium salts

Potas­si­um salts were formed in arid cli­mates when shal­low lagoons and basins evap­o­rat­ed, leav­ing sig­nif­i­cant salt deposits. The main fac­tors influ­enc­ing their for­ma­tion are tec­ton­ic activ­i­ty, the lev­el of salin­i­sa­tion of basins, the inten­si­ty of evap­o­ra­tion and hydro­chem­i­cal con­di­tions. The deposits formed are char­ac­terised by strat­i­form, lens-shaped or lay­ered types of occur­rence, depend­ing on geo­log­i­cal con­di­tions.

Potash salt deposits in Ukraine

In Ukraine, potash salt deposits are con­cen­trat­ed main­ly in the Pre­carpathi­an mar­gin­al trough, with­in the Pre­carpathi­an potash-bear­ing basin. They are con­fined to the Kalush lay­ers of the Steb­nyk and Vorotyshche for­ma­tions of the Neo­gene age. The deposits are strat­i­form or lens-shaped, with a thick­ness of 3 to 120 metres, and are locat­ed at depths of 600–700 metres.

Ukraine’s potash reserves are includ­ed in the State Bal­ance Sheet for 13 deposits, with a total vol­ume of 3,602.3 mil­lion tonnes of ore and 383.9 mil­lion tonnes of K₂O in cat­e­gories A+B+C1+C2. How­ev­er, these data are con­sid­ered out­dat­ed, as they were approved in 1948–1960, based main­ly on pre-war mate­ri­als from Pol­ish geol­o­gists, with­out detailed geo­log­i­cal explo­ration and tak­ing into account cur­rent changes in hydro­ge­o­log­i­cal, envi­ron­men­tal and oth­er con­di­tions.

The Steb­nyk deposit of potas­si­um salts was dis­cov­ered in 1834, and its devel­op­ment began in 1922. It belongs to the Zagorsk and Verkhniy Vorotyshchen­skyi areas of the Pre­carpathi­an trough, where five potas­si­um hori­zons have been iden­ti­fied. These hori­zons lie among salt-bear­ing sandy-clayey brec­cias and clayey rock salt. The most pow­er­ful is the sec­ond hori­zon, which con­sists of six main lay­ers. The main min­er­als are halite, kai­nite, lang­bei­nite, and sylvite; impu­ri­ties include poly­halite and kieserite. Sec­ondary min­er­als include anhy­drite, shen­ite, gyp­sum, epsomite and car­nal­lite. Cai­nite, lang­bei­nite and sylvite form crys­talline mix­tures with halite.

The Kalush-Golyn­skoye deposit belongs to the Golyn­skoye Miocene for­ma­tion and includes sylvi­nite hori­zons occur­ring among salt-bear­ing rocks. The main min­er­als are red, pink and white sylvi­nite with admix­tures of anhy­drite, poly­halite and car­nal­lite. Cai­nite deposits are formed by thin lay­ers of kai­nite, kai­nite-halite, halite and poly­halite-clay mix­tures. With­in the Golyn syn­cline, there are more potas­si­um-bear­ing hori­zons. They are divid­ed into car­nal­lite, kai­nite, sylvi­nite and lang­bei­nite-kai­nite, often con­tain­ing admix­tures of halite, poly­halite and kieserite.

There are sev­er­al oth­er potas­si­um salt deposits in the Pre­carpathi­an region: Boryslav, Dobro­gos­tiv, Pom­yar­ki, Ulich­no, Nyniv, Dregolukske, Hirke, Rosil­nyanske, Starun­sk, Markivske, Molod­kivske, Kadob­na, Trostyanetske, Tura Vely­ka, and Mor­shynske. How­ev­er, they are not yet ready for indus­tri­al devel­op­ment.

In the Dnipro-Donets region, potas­si­um salts have been found in 16 domes, but only the Rom­ny deposit has been found to have indus­tri­al potas­si­um con­tent (KCl up to 39%) at a depth of 300–500 metres. The rest of the deposits are locat­ed at a depth of 1.5–2 km, which makes the region promis­ing for the search for new potash salt deposits.

With­in the Donet­sk Basin, two potas­si­um-bear­ing zones have been dis­cov­ered among the salt deposits of the Low­er Per­mi­an Kram­a­torsk For­ma­tion. The upper zone is rep­re­sent­ed by sylvi­nite-car­nal­lite deposits (up to 60 m thick), while the low­er zone is rep­re­sent­ed by sylvi­nite deposits (70–100 m thick). The depth of occur­rence is 600‑1000 m, and the esti­mat­ed reserves are 1 bil­lion tonnes. Potash salts are rep­re­sent­ed by car­nal­lite, sylvi­nite, poly­galeite and lang­bei­nite. The main lay­ers are char­ac­terised by a high KCl con­tent in sylvi­nite (up to 21.3%).

Use of potash salts

Potash salts play an impor­tant role in many areas of the econ­o­my, pro­vid­ing key indus­tries with the nec­es­sary raw mate­ri­als. They are most impor­tant for agri­cul­ture, as they are the basis for the pro­duc­tion of min­er­al fer­tilis­ers. Potas­si­um improves plant growth, increas­es crop yields and the qual­i­ty of agri­cul­tur­al prod­ucts, and improves resis­tance to drought, dis­ease and adverse con­di­tions. Potas­si­um-based fer­tilis­ers are par­tic­u­lar­ly impor­tant for crops that are sen­si­tive to chlo­rine, such as grapes, cit­rus fruits and tobac­co.

The chem­i­cal indus­try wide­ly uses potas­si­um salts to man­u­fac­ture prod­ucts that are used in phar­ma­ceu­ti­cals, explo­sives, water treat­ment and the cre­ation of var­i­ous chem­i­cal reagents. Met­al­lur­gy also uses potas­si­um com­pounds as flux­es that low­er the melt­ing point of met­als and improve the ener­gy effi­cien­cy of process­es.

In the food indus­try, potas­si­um salts are used as food addi­tives, in par­tic­u­lar for the pro­duc­tion of table salt sub­sti­tutes and preser­v­a­tives. Oth­er indus­tries, such as tex­tiles, ener­gy and con­struc­tion, also find spe­cif­ic uses for potash com­pounds.

In addi­tion, potash salts have envi­ron­men­tal val­ue. They are used to improve degrad­ed land, reduce soil acid­i­ty and main­tain agroe­co­log­i­cal bal­ance. This con­tributes to the ratio­nal use of resources and the sus­tain­able devel­op­ment of agri­cul­ture and envi­ron­men­tal pro­tec­tion activ­i­ties.

Potas­si­um salts are there­fore a strate­gi­cal­ly impor­tant resource for Ukraine, the poten­tial of which remains large­ly untapped due to out­dat­ed geo­log­i­cal data, envi­ron­men­tal prob­lems and insuf­fi­cient invest­ment in the indus­try. Their extrac­tion and ratio­nal use are cru­cial for the coun­try’s eco­nom­ic devel­op­ment, espe­cial­ly in the con­text of ensur­ing food secu­ri­ty, devel­op­ing the chem­i­cal indus­try and main­tain­ing eco­log­i­cal bal­ance.

Giv­en the geo­log­i­cal prospects of the deposits in the Carpathi­an Basin, the Dnipro-Donets region and the Donets Basin, Ukraine has every oppor­tu­ni­ty to become an impor­tant play­er in the glob­al potash fer­tilis­er mar­ket. To achieve this, it is nec­es­sary to reassess reserves, mod­ernise min­ing enter­pris­es, intro­duce the lat­est tech­nolo­gies and ensure com­pli­ance with envi­ron­men­tal stan­dards. The resump­tion of potash salt min­ing could become one of the key fac­tors in the devel­op­ment of the nation­al econ­o­my and its com­pet­i­tive­ness at the inter­na­tion­al lev­el.