Man­ganese ores. Char­ac­ter­is­tics, dis­tri­b­u­tion and gen­e­sis

Man­ganese is one of the key ele­ments in the met­al­lur­gi­cal indus­try, play­ing an impor­tant role in the pro­duc­tion of steel and oth­er alloys. Its ores are dis­tin­guished by high chem­i­cal activ­i­ty and a vari­ety of min­er­al for­ma­tions, which makes them an impor­tant resource for indus­try. Man­ganese ores 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 fer­rous met­al ores.

Characteristics and properties

Man­ganese is a sil­very-white brit­tle met­al, hard­ness 5–6 (on the Mohs scale), has para­mag­net­ic prop­er­ties. Oxi­da­tion states from +2 to +7, the most com­mon are +2, +4, +7. In dry air it oxi­dizes from the sur­face, when heat­ed it burns in air. It dis­solves eas­i­ly in acids, inter­acts vig­or­ous­ly with halo­gens, does not react with hydro­gen, but absorbs it with the for­ma­tion of sol­id solu­tions.

About 150 min­er­als con­tain­ing man­ganese are known, the most com­mon of which are pyro­lusite, haus­man­ite, brown­ite, man­gan­ite, psilome­lane (a mix­ture of man­ganese oxides and hydrox­ides), rhodochrosite, ver­na­dite. Due to its crys­tal­lo­chem­i­cal prox­im­i­ty to Fe, Mg, Ca, man­ganese is wide­ly rep­re­sent­ed as an iso­mor­phic impu­ri­ty in rock-form­ing min­er­als (olivines, gar­nets, micas, car­bon­ates).

Man­ganese ores are nat­ur­al min­er­al for­ma­tions con­tain­ing man­ganese in such com­pounds and con­cen­tra­tions that their indus­tri­al use is tech­ni­cal­ly pos­si­ble and eco­nom­i­cal­ly fea­si­ble. Man­ganese in ores is present in the form of var­i­ous oxide com­pounds, car­bon­ates, and sil­i­cates.

Oxide ores are of great­est indus­tri­al impor­tance, in which the main ore min­er­als are man­ganese oxides and hydrox­ides: pyro­lusite, psilome­lane, man­gan­ite, brown­ite, haus­man­ite, cryp­tome­lane, hol­lan­dite, coro­na­dite, bixbyite, insu­tite, bernes­site, todor­kite, etc. They are inten­sive­ly used in indus­try, since they have a high man­ganese con­tent (25–30%) and are eas­i­ly enriched. Oxide ore con­cen­trates are high-qual­i­ty raw mate­ri­als suit­able for the pro­duc­tion of fer­ro­man­ganese and for the chem­i­cal indus­try.

Oxide ores include per­ox­ide ores, which are char­ac­ter­ized by a pre­dom­i­nant­ly pyro­lusite min­er­al com­po­si­tion and usu­al­ly con­tain more than 40% man­ganese. The cri­te­ri­on for clas­si­fy­ing man­ganese ores as per­ox­ide ores is the per­ox­ide coef­fi­cient — the ratio of man­ganese diox­ide to the total man­ganese con­tent (K = MnO2/Mn). Ores are clas­si­fied as per­ox­ide if the per­ox­ide coef­fi­cient is ≥ 1.3 with a MnO₂ con­tent ≥ 41.8. Of sec­ondary impor­tance are car­bon­ate ores com­posed main­ly of man­ganese car­bon­ates: cal­ci­um rhodochrosite, manganocal­cite, oligo­nite with a man­ganese con­tent of 20–25%. These ores are used by indus­try on a small scale due to the low man­ganese con­tent, dif­fi­cult enrich­ment and high cost of con­cen­trates, but their share in man­ganese pro­duc­tion is con­stant­ly grow­ing.

Sil­i­cate, main­ly quartz-rhodonite-bus­tamite and spes­sar­tine, ores are formed dur­ing strong meta­mor­phism, and with weak meta­mor­phism, brown­ite-haus­man­ite ores arise. They, as a rule, con­tain a lot of sil­i­ca, are mechan­i­cal­ly dif­fi­cult to enrich and there­fore are mined to a lim­it­ed extent. Some­times these ores are used as orna­men­tal stones. Their oxi­dized vari­eties are of greater impor­tance.

Oxide-car­bon­ate ores (mixed) are a tran­si­tion­al type between oxide and car­bon­ate. They are rep­re­sent­ed by both oxides (man­gan­ite, pyro­lusite, psilome­lane) and car­bon­ates (rhodochrosite, manganocal­cite) of man­ganese, the con­tent of which is about 25%.

Oxi­dized ores are formed in oxi­da­tion zones of deposits of oxide, car­bon­ate, sil­i­cate and oth­er types of ores. They are com­posed of man­ganese oxides and hydrox­ides that are sta­ble in oxi­da­tion zones. The man­ganese con­tent in them is over 40%. They are mined in sig­nif­i­cant quan­ti­ties.

The great­est indus­tri­al val­ue is pos­sessed by oxide and oxi­dized ores (psilome­lan-pyro­lusite and man­gan­ite), which con­tain (%): Mn – 23.4–52.0; Fe₂O₃ – 0.9–2.3; FeO – 0.20–0.63; P₂O₅ – 0.321–0.686, as well as car­bon­ate ores, main­ly rhodochrosite, with a con­tent (%): Mn – 11.4–25.2; Fe₂O₃ 0.3–1.0; FeO – 0.5–1.2; P₂O₅ – 0.314–0.466. Car­bon­ate ores are usu­al­ly formed dur­ing dia­ge­n­e­sis at rel­a­tive­ly great depths, in con­di­tions of hydro­gen sul­fide envi­ron­ment and oxy­gen defi­cien­cy.

The main indus­tri­al com­po­nents of man­ganese ores are man­ganese and iron, slag-form­ing com­po­nents include SiO₂, Al₂O₃, CaO, MgO, and harm­ful impu­ri­ties include phos­pho­rus, the sul­fur con­tent is irrel­e­vant, since it turns into slag dur­ing smelt­ing.

Of the phys­i­cal char­ac­ter­is­tics of man­ganese ores, the most impor­tant are the dimen­sions of the mate­r­i­al (the best are sol­id lumpy ores), the degree of frac­tur­ing of the ores, their resis­tance to crush­ing (not less than 60 kg/cm²), poros­i­ty and mois­ture capac­i­ty, and oth­er para­me­ters.

Man­ganese is obtained by elec­trol­y­sis and reduc­tion of its oxides with sil­i­con or by alu­minother­mic meth­ods. Nat­ur­al man­ganese ores are usu­al­ly enriched, obtain­ing con­cen­trates — com­mod­i­ty ores. Enrich­ment is car­ried out by ini­tial crush­ing and wash­ing with the sub­se­quent use of grav­i­ta­tion­al, mag­net­ic, and flota­tion meth­ods. Oxi­dized and oxide-car­bon­ate ores are con­sid­ered to be con­di­tion­al if the man­ganese con­tent in the unen­riched ore is not less than 17%, the yield of the washed ore is not less than 25% and the min­i­mum man­ganese con­tent in the washed ore is 25%. Con­di­tion­al car­bon­ate ores must con­tain not less than 13% Mn with a washed ore con­tent of 22% Mn and not more than 20% sil­i­ca. The met­al­lur­gi­cal indus­try uses com­mod­i­ty ores with a man­ganese con­tent of 25–56%.

Genetic and geological-industrial types of deposits

Man­ganese ore deposits include sed­i­men­ta­ry, vol­canogenic-sed­i­men­ta­ry and meta­mor­phogenic deposits, iron-man­ganese nod­ules of the ocean floor and weath­er­ing deposits.

Sed­i­men­ta­ry deposits are of the great­est indus­tri­al impor­tance, con­cen­trat­ing about 80% of the world’s man­ganese ore reserves. Exam­ples: Nikopol, Chiatur, Veliko­tok­mat deposits. They are asso­ci­at­ed with coastal-marine and lagoon Oligocene deposits. The ore-bear­ing hori­zon con­sists of sev­er­al ore beds sep­a­rat­ed by ore-free lay­ers. Ores are divid­ed into oxide, mixed (oxide-car­bon­ate), car­bon­ate and oxide types.

Vol­canogenic-sed­i­men­ta­ry deposits are formed in areas of intense vol­can­ism, asso­ci­at­ed with dia­base-por­phyry, andesite or quartz-ker­ato­phyre com­plex­es. Main ore min­er­als: brown­ite, haus­man­ite, psilome­lane, ver­na­dite. Exam­ple: Ata­suy deposit (Kaza­khstan). Ores often con­tain Cu, Ni, Co, Pb, Ba, Zn, Ag.

Meta­mor­phogenic deposits include man­ganese-con­tain­ing sil­i­cate rocks of the Pre­cam­bri­an (gondites, codu­rites). The largest deposits: India, Ghana, South Africa, Brazil. Lay­ers of oxide ores are inter­spersed with man­ganese oxide-sil­i­cate rocks, crys­talline schists and quartzites.

Iron-man­ganese for­ma­tions on the ocean floor occur in the form of nod­ules, plates and crusts at depths of 3000–6000 m. Con­tent: Mn — 25–30%, Fe — 10–12%, Ni — 1–2%, Co — 0.3–1.5%, Cu — 1–1.5%. The reserves of the World Ocean are esti­mat­ed at 100 bil­lion tons, but their indus­tri­al devel­op­ment is a mat­ter of the future.

Weath­er­ing deposits (man­ganese hats) are formed on meta­mor­phosed sil­i­cate and car­bon­ate rocks. They are com­mon in India, Brazil, Rus­sia, Kaza­khstan. They include a series of small lay­ers and lens­es of high-qual­i­ty ores. Resid­ual deposits are formed in areas of trop­i­cal weath­er­ing. Exam­ples: West Africa, Aus­tralia, Brazil. Man­ganese con­tent: 40.4–53.3%. Infil­tra­tion deposits are con­cen­trat­ed in South Africa. The ores are local­ized in karst cav­i­ties of the Trans­vaal series, with a man­ganese con­tent of more than 44%.

Main manganese ore formations of Ukraine

Main man­ganese ore for­ma­tions of Ukraine:

• Man­ganese ter­rige­nous-marine: pyro­lusite-psilome­lane-man­gan­ite oxide ores, pyro­lusite-psilome­lane-rhodochrosite-cal­cite mixed ores, rhodochrosite-cal­cite car­bon­ate ores. Exam­ples: Zelen­odol­sk, Ordzhonikidze, Mar­ganets, Velykyi Tok­mak deposits;
• Meta­mor­phosed vol­canogenic-sed­i­men­ta­ry: rhodonite-rhodochrosite ores. Exam­ple: Pry­luky;
• Weath­er­ing crust: pyro­lusite-psilome­lane-hydro­goethite ores. Exam­ple: Khashchu­vatske;
• Infil­tra­tion: psilome­lane-pyro­lusite ores. Man­i­fes­ta­tions: Carpathi­ans, Crimea.

The Nikopol (Pryd­niprovsky) basin includes the Velyko­tok­matske, Mar­ganetske, Nikopolske and Fedorivske deposits, which are struc­tural­ly con­nect­ed and locat­ed in an arc-shaped strip about 250 km long and up to 20 km wide in the south of the Ukrain­ian Shield. These deposits belong to the plat­form pyro­lusite-hydro­goethite-lep­tochlo­rite for­ma­tion. The man­ganese ore hori­zon lies in the Low­er Oligocene sandy-clayey sed­i­ments, over­ly­ing silt­stones, car­bona­ceous clays and sands of the Upper Eocene or crys­talline base­ment rocks. It is over­lain by Pliocene clays, shelly lime­stones, marls and Qua­ter­nary loams with a total thick­ness of 15–80 m. The west­ern part of the basin is being devel­oped by JSC Pokrovsky GOK, and the east­ern part by JSC Mar­ganetske GOK.

The Nikopol deposit is the largest in terms of area and reserves. It is locat­ed in the Dnipropetro­vsk region on the north­ern bank of the Kakhov­ka reser­voir between the mouth of the Baza­vluk Riv­er in the west and the city of Nikopol in the east. The ore seam dips gen­tly to the south and is com­pli­cat­ed by gen­tle fold­ing. Its thick­ness varies from a few cen­time­ters to 4–5 m in the south and in the cen­ter of the deposit (aver­age 2–3 m); the depth of occur­rence is 20–80 m.

The Velyko­tok­matske deposit, locat­ed in the east­ern part of the Nikopol basin, has total reserves of 1,726.6 mil­lion tons, of which 1,578.2 mil­lion tons are con­firmed. The aver­age man­ganese con­tent in the ores is:
- oxide: 31.0%
- oxide-car­bon­ate: 27.2%
- car­bon­ate: 23.4%.

Ore deposits include loams, angu­lar lumps, round­ed con­cen­tri­cal­ly lay­ered for­ma­tions, con­tin­u­ous lay­ers and earthy mass, which make up to 50% of the thick­ness. Car­bon­ate ores are hid­den, micro- and coarse-crys­talline. Oxide ores con­sist of man­ganese oxides and hydrox­ides, and are divid­ed into lumpy, pisolitic, con­cre­tionary, con­tin­u­ous, sandy and earthy. Oxide-car­bon­ate ores are rep­re­sent­ed by lay­ers of loamy car­bon­ate ores, alter­nat­ing lay­ers of car­bon­ate ore with inclu­sions of man­gan­ite pisolitic and clay, lumps of man­ganese hydrox­ides and con­cre­tions of man­ganese car­bon­ates. Car­bon­ate ores are lumpy and con­tin­u­ous, often with con­cen­tri­cal­ly shell-like con­cre­tions, and con­sist main­ly of the min­er­als manganocal­cite and cal­ci­um rhodochrosite.

The prospects for the devel­op­ment of the Nikopol Basin are asso­ci­at­ed with the devel­op­ment of low-phos­pho­rus ores of the Fedorivske deposit (con­cen­trate with a con­tent of 49% man­ganese), the improve­ment of car­bon­ate ore enrich­ment tech­nolo­gies, the uti­liza­tion of enrich­ment sludge (180 mil­lion tons) and slags from fer­ro­man­ganese pro­duc­tion (20 mil­lion tons).

Sed­i­men­ta­ry and hyper­genic man­ganese deposits, in par­tic­u­lar Bur­shtynske in the Ivano-Frankivsk region, which was dis­cov­ered in 1951 and stud­ied in 1952–1954 (M.P. Koval­e­va and oth­ers). This deposit was stud­ied by such sci­en­tists as D.P. Bobrovnyk, V.O. Khmelevsky, E.O. Yanchuk, L.I. Kul­ish, E.O. Kul­ish and oth­ers.
The deposit con­sists of ore-bear­ing Miocene man­ganese lime­stones, clays and marls, the thick­ness of which reach­es 26 meters. These deposits are locat­ed in anhy­drite stra­ta, the width of which can reach 40%. The roof of the deposit varies from 0.5 to 8–13 km, and the con­tent of oxi­dized gyp­sum reach­es 40%. How­ev­er, due to its small size and rel­a­tive com­plex­i­ty of extrac­tion, this deposit is not of sig­nif­i­cant indus­tri­al inter­est. In addi­tion, Ukraine sat­is­fies its needs for man­ganese at the expense of Oligocene ores of the Nikopol basin.

Man­ganese-iron ores of the Cim­mer­ian age are con­cen­trat­ed main­ly in the Kerch iron ore basin, where iron ores are enriched in man­ganese. The man­ganese con­tent in dif­fer­ent types of ores is: “tobac­co” — up to 1.19%, “brown” — up to 2.22%, “caviar” — up to 13.93%, oxide nod­ules — up to 6.28%, car­bon­ate nod­ules — up to 22.02%. The total man­ganese reserves in the Kerch Basin are esti­mat­ed at 40 mil­lion tons. The state bal­ance of min­er­al reserves of Ukraine takes into account eight iron ore deposits of the Kerch Basin, which are not being devel­oped.

Hyper­gene Meso-Ceno­zoic deposits of iron-man­ganese ores include the for­ma­tion of lat­erite, kaolin and hydromi­ca weath­er­ing crusts, in par­tic­u­lar the Khashchu­vatske deposit, where ore-bear­ing weath­er­ing crusts enriched in man­ganese are devel­oped in Pre­cam­bri­an stra­ta. These ore-bear­ing hori­zons are traced to a depth of 40 m and con­tain about 30% man­ganese. The reserves of this deposit are not includ­ed in the State Bal­ance.

The prospects for the devel­op­ment of the man­ganese indus­try in Ukraine are asso­ci­at­ed with the devel­op­ment of iron-man­ganese ores in the Mid­dle Pobuzhzhia, sed­i­men­ta­ry car­bon­ate and oxide hyper­genic ores of the Miocene of the Voly­no-Podil­s­ka plate and the Carpathi­an fold­ed sys­tem, as well as sed­i­men­ta­ry man­ganese-iron ores of the Kerch Basin and iron-man­ganese nod­ules and crusts of the Qua­ter­nary age at the bot­tom of the Black Sea.

Conclusions

Man­ganese is an impor­tant indus­tri­al met­al used in the pro­duc­tion of fer­ro­man­ganese, alloys, chem­i­cal com­pounds and oth­er prod­ucts. It is a com­po­nent of many min­er­als and ores that occur in nature in the form of oxides, car­bon­ates, sil­i­cates and oth­er com­pounds.

Man­ganese ores are used in met­al­lur­gy, the chem­i­cal indus­try and oth­er indus­tries due to their unique physic­o­chem­i­cal prop­er­ties and high man­ganese con­tent. The devel­op­ment of ore enrich­ment tech­nolo­gies and the improve­ment of min­ing meth­ods are impor­tant direc­tions for the future indus­tri­al use of man­ganese resources.