Kaolin clays are a promis­ing min­er­al of the Kyiv indus­tri­al region. Kaolin is a clay min­er­al sub­stance includ­ed in the list of min­er­als of nation­al impor­tance and which is wide­ly used in var­i­ous indus­tries. In total, 3 deposits and sev­er­al dozen man­i­fes­ta­tions of kaolin suit­able for the pro­duc­tion of refrac­to­ries, ceram­ics, paints, paper, etc. were record­ed with­in the Kyiv region.

Uses of kaolin

Kaolin is one of the key com­po­nents in the pro­duc­tion of refrac­to­ry mate­ri­als — sub­stances with high resis­tance to ele­vat­ed tem­per­a­tures. Due to its ther­mal sta­bil­i­ty, low ther­mal con­duc­tiv­i­ty, and resis­tance to defor­ma­tion, kaolin-based mate­ri­als can with­stand extreme­ly high tem­per­a­tures with­out degra­da­tion. It is wide­ly used in fur­naces, cru­cibles, com­bus­tion cham­bers, and oth­er ther­mal equip­ment.

Kaolin is also a fun­da­men­tal raw mate­r­i­al in the pro­duc­tion of porce­lain, faience, tiles, san­i­tary ware, and oth­er ceram­ic prod­ucts. It pro­vides white­ness, tex­ture, and mechan­i­cal strength, mak­ing ceram­ics both durable and aes­thet­i­cal­ly appeal­ing. In addi­tion, kaolin is wide­ly used in the paint indus­try, where it improves pig­ment dis­per­sion, col­or sta­bil­i­ty, and coat­ing tex­ture. In paper pro­duc­tion, it enhances smooth­ness, bright­ness, and uni­for­mi­ty of the sur­face.

Anoth­er impor­tant appli­ca­tion of kaolin is in phar­ma­ceu­ti­cals and cos­met­ics, where it is used as an absorbent and filler. In agri­cul­ture, kaolin is applied as a soil addi­tive that improves struc­ture, mois­ture reten­tion, drainage, and helps reduce ero­sion.

Genesis of kaolin

The gen­e­sis of Kaolin depends on its mode of for­ma­tion and ori­gin. Two main types are dis­tin­guished: pri­ma­ry and sec­ondary kaolin. Pri­ma­ry kaolin forms through the chem­i­cal decom­po­si­tion of gran­ite and oth­er sil­i­cate rocks. This process is extreme­ly slow and may take mil­lions of years.

The west­ern part of Kyiv region lies at the junc­tion of two kaolin sub­provinces: the Podil­lian and Cen­tral sub­provinces. The geo­log­i­cal base­ment in the area of deposits includes gran­ites and migmatites of the Uman com­plex, pla­giogran­i­toids of the Zveny­horod­ka com­plex, as well as their weath­er­ing crusts. With­in Kyiv region, iso­lat­ed kaolin out­crops occur in riv­er val­leys and ravines, while most of the area is cov­ered by sed­i­men­ta­ry deposits. The max­i­mum thick­ness of pri­ma­ry kaolin is asso­ci­at­ed with tec­ton­ic fault zones, where weath­er­ing process­es pen­e­trat­ed to sig­nif­i­cant depths of more than 100 m. Lin­ear weath­er­ing crusts occur as elon­gat­ed belts up to 1.5 km wide and 5–10 km long.

The kaolin dis­trict of Cen­tral Polis­sia is char­ac­ter­ized by a denud­ed zone of nor­mal kaolins and a pre­dom­i­nance of thick alka­line kaolins, sim­i­lar to those of the Dubrivka–Khmelivka kaolin dis­trict. Com­pared to nor­mal kaolins, they have a high­er alka­li con­tent (1.5–2% up to 4–6%, main­ly potas­si­um), where­as in nor­mal kaolins it does not exceed 0.5–1%. Alka­line kaolins con­tain a sig­nif­i­cant amount of relict micro­cline grains and are more valu­able because they can be used as a com­plex kaolinite–feldspar raw mate­r­i­al.

Sec­ondary kaolin forms through rede­po­si­tion process­es, when pri­ma­ry kaolin is erod­ed and trans­port­ed from its orig­i­nal for­ma­tion site by nat­ur­al agents such as water, wind, or glac­i­ers. In Kyiv region, the for­ma­tion of ero­sion-tec­ton­ic pale­o­val­leys dur­ing the Low­er Cre­ta­ceous and Mid­dle Juras­sic peri­ods led to riv­er sys­tem devel­op­ment. In flood­plain envi­ron­ments, sand–clay deposits accu­mu­lat­ed, host­ing sec­ondary kaolin deposits. As a result, sec­ondary kaolin is typ­i­cal­ly less pure and may con­tain impu­ri­ties such as sand, clay, iron oxides, and rock frag­ments.

Kaolin occurrences and deposits in Kyiv region

Pri­ma­ry kaolin is used as raw mate­r­i­al for glass pro­duc­tion and for porce­lain and faience ceram­ics.
With­in the region, 2 deposits that are not devel­oped and more than 10 man­i­fes­ta­tions of pri­ma­ry kaolin are account­ed for. The most stud­ied are the kaolins of the Lavrykivskyi and Kapustinet­skyi deposits.

The Lavrykivske deposit is locat­ed north­west of the vil­lage of Lavryky. It was dis­cov­ered dur­ing explo­ration works in 1996. The deposit rep­re­sents a com­plex-shaped ore body that com­bines both nor­mal and alka­line kaolins. The thick­ness of con­di­tioned pri­ma­ry kaolins varies from 3 to 12.5 m, and their depth varies from 6.5 to 15 m. The raw kaolin of the Lavrykiv deposit con­sists of kaoli­n­ite — 65–78 %, with an admix­ture in nor­mal kaolins — smec­tite — 9–14 %, in alka­line — potas­si­um feldspars — 7–13 %, quartz — 5–8 % and hydromi­ca — 1–6%. Raw kaolin has high white­ness — 65–85%, plas­tic­i­ty num­ber — 8–16, fire resis­tance — 1750–1770° C.

The Kapustyntske deposit is locat­ed on the south­east­ern out­skirts of the vil­lage of Kapustyntsi. It was dis­cov­ered dur­ing explo­ration work in 1996. The deposit area cov­ers approx­i­mate­ly 40 hectares. The weath­er­ing crust with­in the deposit is wide­spread every­where, with a thick­ness of 1–6 m or more. In the pro­file of the weath­er­ing crust, nor­mal kaolins pre­dom­i­nate, while alka­line kaolins occur in iso­lat­ed lay­ers. The pri­ma­ry Kaolin deposit has a vari­able thick­ness from 2 to 20 m and a com­plex geo­log­i­cal shape. The thick­ness of over­bur­den rocks varies from 3 to 21.5 m. Kaolins from the Kapustyntske deposit have a high­er alu­mi­na con­tent (55.6%) and low­er iron and man­ganese oxide con­tent. This allows the use of enriched kaolin in the fine-ceram­ic indus­try in all direc­tions: for the pro­duc­tion of porce­lain and earth­en­ware mass­es of the KF‑3 brand; elec­trophor­phore brands KE‑1, KE‑2; for the elec­tro­chem­i­cal indus­try — KAH‑2, KAS; which can ensure a wide range of their imple­men­ta­tion.

With­in Kyiv Oblast, kaolin has been iden­ti­fied in numer­ous bore­holes at depths of 20–60 m, with thick­ness rang­ing from 1–2 m to 47 m. Dur­ing geo­log­i­cal map­ping and explo­ration, sev­er­al occur­rences were iden­ti­fied:
Hayok (4 km to the west of the vil­lage of Hayok),
Movchanivskyi (3 km west of Rokytne set­tle­ment)
Rotot­skyi (1 km east of Rotok rail­way sta­tion)
Tomylivskyi (north­ern out­skirts of Tomyliv­ka vil­lage)
Fur­sivskyi (3 km north­west of Fursy vil­lage)
The over­bur­den-to-ore ratio in these occur­rences varies from 2:1 to 4:1. The com­bined Fe₂O₃ + TiO₂ con­tent exceeds 2%, and refrac­tori­ness ranges from 1720 to 1770°C.

Sec­ondary kaolin – refrac­to­ry raw mate­r­i­al
Sec­ondary kaolin is also known with­in Kyiv region. First of all, this includes the Pyshchykivske deposit (cur­rent­ly not being exploit­ed), as well as about ten occur­rences of sec­ondary kaolin asso­ci­at­ed with pale­ode­pres­sions of low­er Cre­ta­ceous and Buchak age.

Pyshchykivske deposit is locat­ed between the vil­lages of Pyshchyky and Velykopolovetske on arable land. The kaolin deposits were sur­veyed and explored dur­ing 1962–1966. Struc­tural­ly, the deposit is asso­ci­at­ed with the Yablunivka–Fastiv pale­ode­pres­sion of Low­er Cre­ta­ceous age. In the roof of the sec­ondary kaolin, fine-grained, often kaolin­ized quartz sands occur, while in the base there are coarse-grained Low­er Cre­ta­ceous sands or kaolin weath­er­ing crusts of crys­talline rocks. The pow­er ratio of con­di­tioned sec­ondary kaolins and over­bur­den is 1:8. The pro­duc­tive deposit capac­i­ty is between 0.2 and 18.4 m. The deposit con­sists of three kaolin lens­es sep­a­rat­ed by sandy for­ma­tions. The raw mate­r­i­al is a earthy rock of light-gray and gray col­or. High-puri­ty kaolins dom­i­nate (80–85%), while oth­er vari­eties con­tain var­i­ous impu­ri­ties. The refrac­tori­ness of the kaolin is 1730–1770°C.

With­in the Oril deposits of the Mid­dle Juras­sic, north of the city of Bila Tserk­va, and 4 km south­east of the vil­lage of Terezyne, the Terezynske occur­rence of sec­ondary Kaolin is known. The thick­ness of the min­er­al here varies from 8.5 to 13.8 m, with a depth of occur­rence of 50.6–53.0 m. The refrac­tori­ness is 1730–1770°C.

Sec­ondary kaolins are also wide­spread in deposits of the Bathon­ian and Albian stages of the Buchak series and the Novopetrivs­ka suite. The thick­ness of the lay­ers ranges from 0.3 to 21.0 m. The fol­low­ing occur­rences have been iden­ti­fied:
Doro­hin­skyi (north­ern out­skirts of the vil­lage of Doro­hin­ka)
Vysh­nivskyi (south­ern out­skirts of the vil­lage of Vysh­nia)
Volyt­skyi (1 km north­west of the vil­lage of Volyt­sia)

Thus, the extrac­tion and pro­cess­ing of kaolin in Kyiv Oblast will have a pos­i­tive impact, cre­at­ing a sig­nif­i­cant num­ber of jobs for the local pop­u­la­tion and con­tribut­ing to the social and eco­nom­ic devel­op­ment of the region. In addi­tion, kaolin pro­duc­tion opens new oppor­tu­ni­ties for entre­pre­neurs and encour­ages invest­ment in the sec­tor.

How­ev­er, it is impor­tant to main­tain a bal­ance between the indus­tri­al extrac­tion of kaolin and envi­ron­men­tal pro­tec­tion. Kaolin min­ing is asso­ci­at­ed with soil dis­tur­bance, which may have an impact on ecosys­tems and the land­scape. There­fore, it is essen­tial to devel­op and imple­ment envi­ron­men­tal­ly sus­tain­able meth­ods of kaolin extrac­tion and uti­liza­tion, ensur­ing min­i­mal neg­a­tive con­se­quences for the envi­ron­ment.

LIST OF REF­ER­ENCES USED:
1. Антропогеновые отложения Украины. — К.: Наукова думка, 1986
2. Веклич М. Ф., Сиренко Я. А., Матвишина Ж. Я. и др. Палеогеография Киевского Приднепровья. — К.: Наукова думка, 1984.
3. Минерально-сырьевая база строительных материалов Украинской ССР. Киевская обл., 1989.