Ben­tonite clays. Prop­er­ties, appli­ca­tion and sig­nif­i­cance

Ben­tonite clay is a nat­ur­al mate­r­i­al that got its name from Ben­ton, Wyoming, USA, where large deposits of this clay were first dis­cov­ered. Ben­tonite clays are includ­ed in the list of min­er­als of nation­al impor­tance approved by the Res­o­lu­tion of the Cab­i­net of Min­is­ters of Ukraine dat­ed Decem­ber 12, 1994, No. 827, as adsorp­tion raw mate­r­i­al, mold­ing mate­r­i­al for pel­letiz­ing, and raw mate­r­i­al for drilling flu­id prepa­ra­tion.

Properties of bentonite clays

Ben­tonite clays con­sist main­ly of mont­mo­ril­lonite group min­er­als (with admix­tures of hydromi­ca, hydrochlo­rite, paly­gorskite, kaoli­n­ite, etc.), formed as a result of devit­ri­fi­ca­tion and oth­er chem­i­cal trans­for­ma­tions of vol­canic ash. Ben­tonite clay is char­ac­ter­ized by high swelling capac­i­ty and has sorp­tion, adsorp­tion, and cat­alyt­ic prop­er­ties, mak­ing it extreme­ly use­ful in many indus­tries.

Main phys­i­cal prop­er­ties:

• Swelling. Ben­tonite can sig­nif­i­cant­ly increase its vol­ume when in con­tact with water. This prop­er­ty is used in con­struc­tion mate­ri­als to cre­ate water­proof bar­ri­ers.
• Sorp­tion prop­er­ties. Ben­tonite clay can absorb tox­ins, mak­ing it effec­tive in water treat­ment sys­tems and as an addi­tive in ani­mal feed for remov­ing harm­ful sub­stances.
• Adsorp­tion. Ben­tonite can cap­ture gas­es, odors, and oth­er volatile sub­stances, which is used in house­hold and indus­tri­al fil­ters.

Ben­tonite clays are clas­si­fied into:

• Alka­line earth (cal­ci­um-mag­ne­sium) types, used in min­ing indus­try, foundry pro­duc­tion, con­struc­tion, and food indus­try;
• Alka­line (sodi­um) types which, in addi­tion to the above, can be used in fer­rous met­al­lur­gy and agri­cul­ture;
• Unique white-fired vari­eties — for pro­duc­tion of high-strength porce­lain and faience prod­ucts, phar­ma­co­log­i­cal and cos­met­ic prod­ucts, and man­u­fac­tur­ing of paper grades.

Genetic types of bentonite clay deposits

Main types of ben­tonite clay deposits:

• Hydrother­mal-meta­so­mat­ic (Sari­gyukhske in Arme­nia, Dash-Salakhly in Azer­bai­jan, Vaniske­di in Geor­gia, Pon­za in Italy);
• Vol­canic-sed­i­men­ta­ry (Black Hills in USA, Pyzhiv and Berezhany in Ukraine, Gum­bri in Geor­gia; Ogland­ly in Turk­menistan, Khan­dar in Azer­bai­jan, Azka­mar in Uzbek­istan);
• Ter­rige­nous and col­loidal-sed­i­men­ta­ry (Cherkasy in Ukraine, Byklyan, Tary-Var, Upper Nurlat, Smyshlyaev­ka in the Vol­ga region, Zyryan in the Urals, Lyu­bi­no in Siberia); rep­re­sent­ed by strat­i­form deposits, rarely lens­es, have medi­um and large reserves, but their raw mate­r­i­al qual­i­ty is usu­al­ly low;
• Elu­vial (Ust-Manya, Sakharin, Raz­gon in Rus­sia, Branin in Czech Repub­lic)

Bentonite clays in Ukraine

About 100 deposits and occur­rences of ben­tonites are known in Ukraine in six provinces:

• Tran­scarpathi­an (Horb, Ilnyt­sya, Kish­ta, Kopan), asso­ci­at­ed with the Vyhor­lat-Hutyn ridge and Solotvyno depres­sion (fore­cast resources 15 mil­lion tons);
• Pre-Carpathi­an frontal trough and Volyn-Podil­lia plate (Pyzhiv, Berezhany, Nemyriv, Strutin and oth­ers) (fore­cast resources 18 mil­lion tons);
• Black Sea depres­sion;
• Ukrain­ian Shield (Cherkasy and oth­ers) (fore­cast resources 20 mil­lion tons);
• Indol-Kuban trough of Crimea (Kurtsove, Man­gush) (4 mil­lion tons);
• Donet­sk fold­ed region (fore­cast resources 48 mil­lion tons)

The State Bal­ance of Reserves accounts for 8 deposits of ben­tonite clays (Cherkasy, Horb, Kurtsove, Kudryne, Berezhany, Pyzhiv, etc.) with total bal­ance reserves of cat­e­gories A+B+C₁ 63.9 mil­lion tons, C₂ — 0.2 mil­lion tons, and off-bal­ance — 1.4 mil­lion tons (as of 01.01.2005). The largest deposit in Ukraine is Cherkasy (con­tain­ing 86% of all Ukraine’s reserves); oth­er deposits — Berezhany, Bilovod­sk, Velykocher­netche, Hor­bkiv, Hry­horiv, Ilnyt­sya, Kudryne, Kurtsove, and oth­ers have sig­nif­i­cant­ly small­er reserves.

4 deposits (Cherkasy, Horb, and oth­ers) are being devel­oped as raw mate­ri­als for foundry pro­duc­tion, drilling oper­a­tions, etc. The clays are main­ly alka­line earth polymin­er­al, of mont­mo­ril­lonite and bei­del­lite-mont­mo­ril­lonite com­po­si­tion. Alka­line earth types pre­dom­i­nate (Ca-Mg with Na, K, etc. admix­tures), while alka­line types (Na with K, Ca, Mg admix­tures) are less com­mon (Kish­ta deposit).

Before Rus­si­a’s full-scale inva­sion of Ukraine, geo­log­i­cal explo­ration was con­duct­ed at the Hry­horiv deposit (Don­bas), Pavliv­ka and Shy­maniv areas (Dnipropetro­vsk region), Pil­i­a­va deposit (Vin­nyt­sia region), and explorato­ry assess­ment work was car­ried out in Polta­va, Sumy, and Kharkiv regions.

Applications of bentonite clays

Ben­tonite clay is a valu­able mate­r­i­al due to its unique prop­er­ties and finds wide appli­ca­tion in var­i­ous indus­tries. One of its key areas of use is the oil extrac­tion indus­try, where it is an impor­tant com­po­nent of drilling flu­ids. Its abil­i­ty to swell and cre­ate vis­cous sus­pen­sions makes it indis­pens­able for sta­bi­liz­ing well­bore walls dur­ing oil and gas well drilling. Ben­tonite forms a pro­tec­tive lay­er that pre­vents well­bore col­lapse and ensures a sta­ble drilling process even at great depths. Addi­tion­al­ly, ben­tonite clay is used to absorb and remove harm­ful sub­stances from drilling flu­ids, increas­ing the envi­ron­men­tal safe­ty of the process.

In con­struc­tion, ben­tonite clay is wide­ly used for cre­at­ing water­proof­ing sys­tems due to its water reten­tion prop­er­ties. This makes it indis­pens­able in the con­struc­tion of under­ground stor­age facil­i­ties, foun­da­tions, and tun­nels. The clay is used as part of geosyn­thet­ic clay bar­ri­ers that pro­vide effec­tive pro­tec­tion against water pen­e­tra­tion into struc­tures. Such bar­ri­ers are cost-effec­tive and durable, reduc­ing the risks of infra­struc­ture dam­age due to ground­wa­ter.

Med­i­cine and cos­me­tol­ogy also active­ly use ben­tonite clay due to its cleans­ing and detox­i­fi­ca­tion prop­er­ties. It is the basis of many ther­a­peu­tic oint­ments and cos­met­ic masks. The clay reduces inflam­ma­tion and improves over­all skin con­di­tion. Due to its abil­i­ty to absorb tox­ins, ben­tonite is also used in some med­ica­tions for body cleans­ing.

Water treat­ment is anoth­er impor­tant area of ben­tonite appli­ca­tion. It is active­ly used for waste­water treat­ment and removal of harm­ful sub­stances such as heavy met­als, petro­le­um prod­ucts, and oth­er pol­lu­tants. Due to its high adsorp­tion capac­i­ty, ben­tonite effec­tive­ly reduces water tox­i­c­i­ty lev­els, improv­ing its qual­i­ty before dis­charge into nat­ur­al water bod­ies.

In the food indus­try, ben­tonite clay plays an impor­tant role in wine and juice clar­i­fi­ca­tion process­es. Its abil­i­ty to pre­cip­i­tate sus­pen­sions and col­loids helps ensure prod­uct clar­i­ty and trans­paren­cy, improv­ing its taste qual­i­ties and aes­thet­ic appear­ance. Ben­tonite is also used for puri­fy­ing oils and fats, as it effec­tive­ly binds unwant­ed impu­ri­ties and sed­i­ments while pre­serv­ing the ben­e­fi­cial prop­er­ties of prod­ucts.

Mining of bentonite clays

Ben­tonite clays are extract­ed using the quar­ry method. This means that large areas of soil are removed, reveal­ing clay deposits that lie direct­ly under the earth­’s sur­face. This method is effec­tive and allows obtain­ing large vol­umes of mate­r­i­al. The prof­itable strip­ping ratio (ratio of over­bur­den vol­ume to extract­ed min­er­al vol­ume) for ben­tonite clays is usu­al­ly about 2–3. This means that for each ton of extract­ed clay, it is nec­es­sary to move 2 to 3 tons of over­bur­den. If the strip­ping ratio exceeds these val­ues, extrac­tion may become eco­nom­i­cal­ly unprof­itable due to increased costs of mov­ing over­bur­den.

The slope angle for ben­tonite clays depends on their phys­i­cal and mechan­i­cal prop­er­ties, par­tic­u­lar­ly den­si­ty, mois­ture con­tent, and par­ti­cle cohe­sion. Gen­er­al­ly, for ben­tonite clays, due to their high plas­tic­i­ty and ten­den­cy to swell, rec­om­mend­ed slope angles range from 18 to 30 degrees. How­ev­er, in each spe­cif­ic case, it is nec­es­sary to con­sid­er local con­di­tions, hydro­log­i­cal regime, and oth­er fac­tors.

In con­clu­sion, ben­tonite clays are an extreme­ly impor­tant nat­ur­al resource due to their unique prop­er­ties such as swelling capac­i­ty, sorp­tion, and adsorp­tion qual­i­ties. They find wide appli­ca­tion in oil extrac­tion, con­struc­tion, food indus­try, med­i­cine, and water treat­ment. Ukraine has sig­nif­i­cant ben­tonite deposits, mak­ing it a strate­gi­cal­ly impor­tant mate­r­i­al for many indus­tries. How­ev­er, the devel­op­ment and use of these deposits require detailed plan­ning and an envi­ron­men­tal approach to pre­serve nat­ur­al resources.