Mag­ne­sium salts belong to a group of sed­i­men­ta­ry min­er­als that form when salt water evap­o­rates in closed or semi-closed basins. They are impor­tant because of their chem­i­cal com­po­si­tion, which allows them to be used in indus­try, agri­cul­ture and oth­er sec­tors.

Mag­ne­sium 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 raw mate­r­i­al.

The main min­er­als in this group are:

• cai­nite (KCl·MgSO₄·3H₂O)
• lang­bei­nite (K₂Mg₂(SO₄)₃)
• sylvite (KCl)
• car­nal­lite (KMgCl₃·6H₂O)
• bischof­ite (MgCl₂·6H₂O)

These min­er­als are usu­al­ly found in the form of strat­i­form deposits, which can reach con­sid­er­able thick­ness­es and have a high con­cen­tra­tion of potas­si­um (K) and mag­ne­sium (Mg), as well as impu­ri­ties of oth­er ele­ments.

Physical and chemical properties of magnesium salts

The char­ac­ter­is­tic phys­i­cal and chem­i­cal prop­er­ties of mag­ne­sium salts are:

• Sol­u­bil­i­ty: High sol­u­bil­i­ty in water, which allows these salts to be used as a source of potas­si­um and mag­ne­sium in the form of solu­tions or con­cen­trates.
• Hygro­scop­ic­i­ty: Min­er­als active­ly absorb mois­ture from the air, which affects their stor­age and trans­porta­tion.
• Crys­talline struc­ture: This ensures easy grind­ing and pro­cess­ing of salts dur­ing extrac­tion and pro­cess­ing.
• Resis­tance to exter­nal con­di­tions: Salts retain their prop­er­ties even dur­ing long-term stor­age, but need to be pro­tect­ed from direct con­tact with mois­ture.
• The chem­i­cal com­po­si­tion of mag­ne­sium salts allows them to be used as fer­tilis­ers, com­po­nents in met­al pro­duc­tion, in the chem­i­cal indus­try and oth­er areas.

The genesis of magnesium salts

The gen­e­sis of mag­ne­sium salts is asso­ci­at­ed with sed­i­men­ta­tion process­es that occur in salt basins as a result of sea­wa­ter evap­o­ra­tion. These deposits form at dif­fer­ent stages of sed­i­men­ta­tion, depend­ing on the con­cen­tra­tion of ions in the solu­tion.

Mag­ne­sium salts are formed under spe­cif­ic geo­log­i­cal and cli­mat­ic con­di­tions. The most impor­tant con­di­tion is the pres­ence of a semi-enclosed basin where evap­o­ra­tion exceeds water inflow. Such basins are usu­al­ly locat­ed in regions with a dry and warm cli­mate. The crys­talli­sa­tion process begins with the pre­cip­i­ta­tion of gyp­sum (CaSO₄·2H₂O) and halite (NaCl), which fall out as a result of the water lev­el drop­ping. Fur­ther evap­o­ra­tion leads to the sat­u­ra­tion of the solu­tion with potas­si­um and mag­ne­sium, which con­tributes to the for­ma­tion of potas­si­um-mag­ne­sium min­er­als such as kai­nite, car­nal­lite and lang­bei­nite. As sed­i­men­ta­tion pro­gress­es, dif­fer­ent salt hori­zons are formed, dif­fer­ing in min­er­alog­i­cal com­po­si­tion and con­cen­tra­tion of com­po­nents. In the final stages, salts with a high potas­si­um and mag­ne­sium con­tent are formed, which have the high­est indus­tri­al val­ue. Tec­ton­ic activ­i­ty can influ­ence the for­ma­tion of salt deposits by cre­at­ing fold­ed struc­tures that trap salt deposits. In many cas­es, these process­es con­tribute to the con­cen­tra­tion of salts in the form of sep­a­rate salt-bear­ing hori­zons that are acces­si­ble for extrac­tion.

Thus, mag­ne­sium salts are the prod­uct of a com­plex geo­log­i­cal process that results in the for­ma­tion of sig­nif­i­cant deposits in nature. Their gen­e­sis deter­mines the loca­tion and com­po­si­tion of deposits, which influ­ences the meth­ods of extrac­tion and fur­ther use.

Distribution of magnesium salts

Mag­ne­sium salts are impor­tant resources for indus­try, espe­cial­ly in chem­i­cal pro­duc­tion, agri­cul­ture and met­al­lur­gy. Ukraine has sig­nif­i­cant reserves of these min­er­als, which are con­cen­trat­ed in the Carpathi­an Basin, the Donets Basin and the Crimean lakes and bays. The deposits are rep­re­sent­ed by both pri­ma­ry deposits and solu­tions in brine.

The most famous deposits of mag­ne­sium salts in the Carpathi­an Fore­deep are the Kalush-Golynske and Steb­nyk com­plex deposits. They are notable for their rich com­po­si­tion and sig­nif­i­cant reserves.

The Kalush-Golynske deposit con­sists of two main salt-bear­ing deposits, rang­ing in size from 300×700 to 1000×2000 metres. The thick­ness of indi­vid­ual lay­ers reach­es 50 metres, and the total thick­ness of the deposit is up to 600 metres. The main min­er­als are kai­nite, lang­bei­nite and halite, with admix­tures of kieserite and poly­gale. The aver­age MgO con­tent in the ore is 5.06%, K₂O – 11.25%. These deposits are used to obtain raw mate­ri­als nec­es­sary for the chem­i­cal indus­try.

The Steb­nyk deposit is locat­ed in the Vorotyshche Low­er Miocene for­ma­tion. There are five potas­si­um-mag­ne­sium hori­zons here, with a thick­ness of 30–50 metres and dimen­sions rang­ing from 100×700 to 2000×4000 metres. The main min­er­als are halite, kai­nite, lang­bei­nite and sylvite. The MgO con­tent is 8.32%, K₂O — 10.64%. The total reserves of both deposits are esti­mat­ed at 2 bil­lion tonnes, of which 150 mil­lion tonnes are MgO.

There are sev­er­al sig­nif­i­cant deposits of potas­si­um-mag­ne­sium salts in the Donet­sk Basin, in par­tic­u­lar the Zatu­rynske and Novopodilske deposits. They belong to the Kram­a­torsk For­ma­tion of the Per­mi­an peri­od.

The Zatu­rynske deposit is rep­re­sent­ed by a bischof­ite hori­zon, the thick­ness of which varies from 14.5 to 24 metres, and the area of the deposits is about 200 km². The main com­po­nent is bischof­ite, the con­tent of which in the rock reach­es 88.47%. Halite, kieserite, gyp­sum and oth­er impu­ri­ties are also present.

The Novopodil­sk deposit con­tains three lay­ers of potas­si­um-mag­ne­sium salts. The low­er lay­er con­sists of car­nal­lite, the mid­dle lay­er con­sists of bischof­ite, and the upper lay­er con­sists of car­nal­lite and halite. The thick­ness of the bischof­ite hori­zon reach­es 15–35 metres, and the bischof­ite con­tent in the rock is up to 94%. The reserves of the deposit are esti­mat­ed at 1.68 bil­lion tonnes. Pro­duc­tion at these deposits is car­ried out using the well dis­so­lu­tion method.

The bays and lakes in the Autonomous Repub­lic of Crimea, such as Syvash, Stare and Donu­zlav, con­tain sig­nif­i­cant amounts of dis­solved potas­si­um-mag­ne­sium salts in brine. These resources are formed as a result of the evap­o­ra­tion of the waters of the Sea of Azov, which flows into shal­low bays. The MgO con­tent in brine ranges from 0.38 to 1.15%. Such deposits are promis­ing for extrac­tion and pro­cess­ing.

In addi­tion to clas­sic deposits, meta­mor­phogenic deposits of mag­ne­site and talc-mag­ne­site are promis­ing. Among them are the Pravdin­skoye and Veselyan­skoye deposits. For exam­ple, the Pravdin­skoye deposit con­tains talc-mag­ne­site rocks with an MgO con­tent of up to 41%. Such resources can be used in the pro­duc­tion of heat-resis­tant mate­ri­als, refrac­to­ries and oth­er prod­ucts.

Use of magnesium salts

Potas­si­um-mag­ne­sium salts are wide­ly used in many indus­tries due to their rich chem­i­cal com­po­si­tion. In agri­cul­ture, these salts are the basis for the pro­duc­tion of min­er­al fer­tilis­ers. The potas­si­um in their com­po­si­tion helps to increase yields, improve fruit qual­i­ty and increase plant resis­tance to dis­ease. Mag­ne­sium, in turn, plays an impor­tant role in pho­to­syn­the­sis as a com­po­nent of chloro­phyll. Fer­tilis­ers based on potas­si­um-mag­ne­sium salts, such as kali­mag­ne­sia or kai­nite, are par­tic­u­lar­ly effec­tive for soils with low con­tent of these ele­ments.

In the chem­i­cal indus­try, potas­si­um-mag­ne­sium salts are used to pro­duce var­i­ous mag­ne­sium and potas­si­um com­pounds used in the man­u­fac­ture of poly­mers, arti­fi­cial fibres, dyes, glass and deter­gents. Mag­ne­sium com­pounds are also impor­tant com­po­nents in water purifi­ca­tion tech­nolo­gies, par­tic­u­lar­ly for soft­en­ing and remov­ing heavy met­als.

The met­al­lur­gi­cal indus­try uses potas­si­um-mag­ne­sium salts as a source of metal­lic mag­ne­sium. This met­al is wide­ly used in air­craft con­struc­tion, auto­mo­tive man­u­fac­tur­ing and oth­er high-tech indus­tries where low weight of mate­ri­als is impor­tant. Ukrain­ian enter­pris­es, such as the Kalush Chem­i­cal and Met­al­lur­gi­cal Plant and the Zapor­izhzhia Tita­ni­um-Mag­ne­sium Plant, spe­cialise in the pro­duc­tion of mag­ne­sium from this raw mate­r­i­al.

Potas­si­um-mag­ne­sium salts also play an impor­tant role in phar­ma­ceu­ti­cals. They are used to obtain mag­ne­sium com­pounds, which are used in the pro­duc­tion of antacids, lax­a­tives, and prepa­ra­tions for nor­mal­is­ing the car­dio­vas­cu­lar and ner­vous sys­tems. Potas­si­um is an impor­tant com­po­nent of med­i­cines used in the treat­ment of heart dis­ease.

In the con­struc­tion indus­try, mag­ne­sia salts are used to man­u­fac­ture refrac­to­ry mate­ri­als, mag­ne­sia cements and spe­cial coat­ings that are char­ac­terised by high heat resis­tance, strength and dura­bil­i­ty. In the ener­gy sec­tor, mag­ne­sia com­pounds are key in the pro­duc­tion of heat-resis­tant mate­ri­als and bat­ter­ies.

The wide range of appli­ca­tions for potas­si­um-mag­ne­sium salts demon­strates their strate­gic impor­tance for many indus­tries. The con­stant demand for these salts, espe­cial­ly in agri­cul­ture and met­al­lur­gy, makes them an indis­pens­able resource for the mod­ern econ­o­my. Ukraine, with its sig­nif­i­cant reserves of these min­er­als, has great prospects for their effec­tive use and export.

Thus, Ukraine has sig­nif­i­cant poten­tial for increas­ing the pro­duc­tion of potas­si­um-mag­ne­sium salts. Promis­ing areas include fur­ther explo­ration of the flanks of the Pre­carpathi­an Basin deposits, research into new hori­zons in the Donet­sk Basin, and the devel­op­ment of brine in the Crimean bays. Par­tic­u­lar atten­tion should be paid to the study of non-tra­di­tion­al types of raw mate­ri­als, such as talc-mag­ne­site ores.

Potas­si­um-mag­ne­sium salts play an impor­tant role in Ukraine’s indus­try. Thanks to its sig­nif­i­cant reserves and diver­si­ty of deposits, the coun­try has the oppor­tu­ni­ty to meet its raw mate­r­i­al needs and devel­op its export poten­tial. The ratio­nal use of these resources is an impor­tant task for future eco­nom­ic growth.