Alu­nite is an impor­tant min­er­al from the sul­fate class that con­tains ammo­ni­um and potas­si­um. Due to its unique chem­i­cal com­po­si­tion, it is a valu­able raw mate­r­i­al for the pro­duc­tion of alum, fer­til­iz­ers, and sul­fu­ric acid. In coun­tries such as Chi­na and Azer­bai­jan, alu­nite is also used to obtain alu­mi­na. Its deposits are usu­al­ly con­fined to areas of young vol­can­ism, where they are formed as a result of the hydrother­mal influ­ence of sul­fur gas­es and solu­tions on vol­canic rocks.

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

Physical and chemical properties of alunite

Alu­nite is a quartz-alu­nite rock formed as a result of meta­so­mat­ic process­es in vol­canic tuffs and oth­er acidic rocks under the influ­ence of hot sul­fides.

Chem­i­cal for­mu­la: KAl₃(SO₄)₂(OH)₆. It belongs to the class of sul­fates and is an impor­tant raw mate­r­i­al for the pro­duc­tion of alu­minum, potas­si­um, and sul­fu­ric acid.

• Alu­nite (KAl₃(SO₄)₂(OH)₆) – the main min­er­al that deter­mines the prop­er­ties of the rock.
• Quartz (SiO₂) – gives the rock high hard­ness and sta­bil­i­ty.
• Opal – an amor­phous form of sil­i­con diox­ide, which com­pli­cates the enrich­ment process.
• Barite (BaSO₄) – bar­i­um sul­fate, which some­times occurs as an impu­ri­ty.
• Gyp­sum (CaSO₄·2H₂O) – may be present in small quan­ti­ties.
• Gal­lu­azite and kaoli­n­ite – alu­mi­nosil­i­cates that form as asso­ci­at­ed min­er­als.
• Hematite (Fe₂O₃) – iron oxide, which affects the col­or and phys­i­cal prop­er­ties of the rock.

Alunite ore deposits in Ukraine

In Ukraine, indus­tri­al reserves of alu­nite are con­cen­trat­ed in the Tran­scarpathi­an region, espe­cial­ly in the Vygor­lat-Guty­na ridge. There are four main deposits here—Biyhanske, Bere­hivske, Dobrosilske, and Lopushnyanske—as well as a num­ber of promis­ing ore occur­rences.

The Byi­hanske deposit, locat­ed west of the city of Bere­hove, con­tains sig­nif­i­cant reserves of alu­nite, esti­mat­ed at 195 mil­lion tons. The ore here is char­ac­ter­ized by the pres­ence of opal and barite impu­ri­ties, which com­pli­cates its pro­cess­ing. The main min­er­al com­po­nent is quartz-alu­nite rock formed in Sar­ma­t­ian tuffs.

In the Bere­hove ore field, which cov­ers the Bere­hove, Dobrosil, and Lopush­nyanske deposits, the alu­nite rocks are of bet­ter qual­i­ty. The alu­nite con­tent reach­es 45%, and the ore reserves are esti­mat­ed at 51.4 mil­lion tons. There is no opal here, which sim­pli­fies the pro­cess­ing tech­nol­o­gy. The alu­nite deposit is locat­ed in the upper part of the Vely­ka Bere­hivs­ka Moun­tain.

The Dobrosilske deposit has reserves of 36.8 mil­lion tons with an alu­nite con­tent of 15% to 50%. The Lopush­nyanske deposit has sim­i­lar char­ac­ter­is­tics, with total reserves esti­mat­ed at 10.4 mil­lion tons. There are also promis­ing areas with­in the ore field, such as Kvasovskoye and Muzhievskoye.

Use of alunite

Alu­nite is an impor­tant raw mate­r­i­al for the pro­duc­tion of alum, fer­til­iz­ers, and sul­fu­ric acid. It can be processed using two meth­ods: sul­fate and alka­li-reduc­tion. The first method is used to obtain alu­mi­na, potas­si­um sul­fate, and sul­fu­ric acid, while the sec­ond allows the pro­duc­tion of chlo­rine-free potash fer­til­iz­ers and coag­u­lants for build­ing mate­ri­als.

Alu­nite is also a source of alu­minum for the pro­duc­tion of hard­ened cement and refrac­to­ry mate­ri­als. In Ukraine, min­ing of this ore began in 1975 in Tran­scarpathia, where a met­al­lur­gi­cal plant spe­cial­iz­ing in the pro­duc­tion of alum cur­rent­ly oper­ates in the town of Vyshko­vo.

Alu­nite deposits in Ukraine have sig­nif­i­cant poten­tial for the devel­op­ment of the chem­i­cal and con­struc­tion indus­tries. Despite obsta­cles in ore pro­cess­ing due to impu­ri­ties and oth­er com­po­nents, the prospects for using this raw mate­r­i­al are sig­nif­i­cant. Mod­ern tech­nolo­gies for enrich­ing alu­nite ores can help increase the prof­itabil­i­ty of min­ing and pro­cess­ing this impor­tant resource.