Apatite. Char­ac­ter­is­tics, dis­tri­b­u­tion, and gen­e­sis

Apatite is one of the most impor­tant min­er­als con­tain­ing phos­pho­rus, an ele­ment nec­es­sary for the devel­op­ment of plants, ani­mals, and indus­tri­al tech­nolo­gies. It is wide­ly used in the pro­duc­tion of min­er­al fer­til­iz­ers, phos­phates, phos­phor­ic acid, as well as in met­al­lur­gy, chem­i­cal, and bio­med­ical indus­tries. In Ukraine, apatite ores are found in com­plex deposits, where they are often asso­ci­at­ed with ilmenite, zir­con, and rare earth min­er­als. Despite sig­nif­i­cant reserves, their indus­tri­al devel­op­ment has not yet begun due to a num­ber of eco­nom­ic and tech­no­log­i­cal fac­tors. How­ev­er, with the grow­ing demand for phos­pho­rus resources, the prospects for the devel­op­ment of Ukrain­ian apatite deposits may change.

Apatite 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 an agro­chem­i­cal raw mate­r­i­al.

Physical and chemical properties of apatite

Apatite is a phos­phate min­er­al of the cal­ci­um apatite group with the gen­er­al chem­i­cal for­mu­la Ca₅(PO₄)₃(F,Cl,OH). It is rel­a­tive­ly chem­i­cal­ly sta­ble, but dis­solves at high tem­per­a­tures and in acidic envi­ron­ments, form­ing phos­phor­ic acid. Depend­ing on the anion­ic com­po­nent, there are flu­o­ra­p­atite (Ca₅(PO₄)₃F), chlo­rap­atite (Ca₅(PO₄)₃Cl), and hydrox­y­la­p­atite (Ca₅(PO₄)₃OH), which dif­fer in sta­bil­i­ty and reac­tiv­i­ty.

It crys­tal­lizes in a hexag­o­nal crys­tal sys­tem, form­ing pris­mat­ic or aci­c­u­lar crys­tals, as well as gran­u­lar and dense aggre­gates. Its hard­ness on the Mohs scale is 5, and its den­si­ty is 3.1–3.2 g/cm³. The col­or varies from col­or­less to green, blue, yel­low, brown, and pur­ple depend­ing on impu­ri­ties (rare earth ele­ments, iron, man­ganese). Opti­cal­ly, apatite is trans­par­ent or translu­cent, with a glassy or greasy lus­ter.

Genesis of apatite deposits

Apatite is a typ­i­cal­ly mag­mat­ic and meta­so­mat­ic min­er­al, formed in var­i­ous geo­log­i­cal con­di­tions.
The main genet­ic types of deposits are:

• Mag­mat­ic – asso­ci­at­ed with ultra­ba­sic, gab­broic, and nepheline rocks, in par­tic­u­lar ilmenite-apatite com­plex­es (Kola Penin­su­la, Ukrain­ian Shield (US)).
• Car­bon­atite – formed in deep mag­mat­ic sys­tems and con­tain­ing sig­nif­i­cant amounts of rare met­als (Novopoltavskoye deposit).
• Sed­i­men­ta­ry (phos­pho­rites) – sed­i­men­ta­ry apatite for­ma­tions in marine envi­ron­ments, formed by the accu­mu­la­tion of phos­phates from organ­ic residues.
• Meta­mor­phic – occur dur­ing the trans­for­ma­tion of sed­i­men­ta­ry rocks or mag­mat­ic com­plex­es as a result of high-tem­per­a­ture and tec­ton­ic process­es.

Depend­ing on the con­di­tions of for­ma­tion, apatite ores may con­tain asso­ci­at­ed min­er­als such as ilmenite, mag­netite, zir­con, mon­azite, rare earth ele­ments, and oth­er com­po­nents that deter­mine their indus­tri­al val­ue.

Apatite deposits in Ukraine

Apatite is a valu­able phos­pho­rus raw mate­r­i­al used in the pro­duc­tion of min­er­al fer­til­iz­ers, phos­phates, phos­pho­rus, and phos­phor­ic acid. In Ukraine, apatite ores are found in com­plex ilmenite-apatite deposits, such as Kropy­vnyanske, Stremy­horodske, Torchynske, Fedorivske in the Zhy­to­myr region, and Nosachivske in the Cherkasy region. In addi­tion, apatite is part of rare met­al-apatite deposits, in par­tic­u­lar Novopoltavske in the Zapor­izhzhia region and Davy­d­kivske in the Zhy­to­myr region.

The Stremy­horodske, Novopoltavske, and Nosachivske deposits are being devel­oped under spe­cial per­mits issued to the com­pa­nies Volyn Min­ing and Chem­i­cal Com­pa­ny, Valky-Ilmenite, and TiO­Fab. In Ukraine, there are sev­en deposits on the state bal­ance sheet with total ore reserves of 3.3 bil­lion tons, of which 96.2 mil­lion tons are phos­pho­rus anhy­dride (P₂O₅). How­ev­er, apatite is not cur­rent­ly being mined in Ukraine.

The Stremy­horodske deposit con­tains three ore-bear­ing lay­ers. The upper lay­er is rep­re­sent­ed by pri­ma­ry kaolin with a thick­ness of 3–25 m, in which the aver­age apatite con­tent is 35.9 kg/t. Below lies weath­ered gabronorite with a thick­ness of 10–30 m, where the con­cen­tra­tion of apatite ranges from 25 to 109 kg/t (an aver­age of 30 kg/t). Even deep­er is fresh gabronorite, in which the apatite con­tent reach­es 3–75 kg/t (an aver­age of 23.9 kg/t). The ore deposits are cov­ered by sandy-clayey sed­i­ments 18.7–38.3 m thick. Due to the char­ac­ter­is­tics of the deposits, they can be mined using open-pit meth­ods.

The main indus­tri­al inter­est is in apatite and ilmenite, which are con­cen­trat­ed in pri­ma­ry kaolins and weath­ered gabronorite. Apatite in this rock is rep­re­sent­ed by a mix­ture of flu­o­rine-chlo­rine and hydrox­y­la­p­atite, among which flu­o­ra­p­atite pre­dom­i­nates. The grain size is 0.2–0.8 mm, and they often grow togeth­er with small grains of ilmenite, which com­pli­cates enrich­ment. The total con­tent of apatite in the ore is about 10%, and ilmenite is 15–20%. In the case of indus­tri­al devel­op­ment, it is pos­si­ble to extract up to 150 thou­sand tons of apatite con­cen­trate per year, and the reserves of phos­pho­rus anhy­dride (P₂O₅) in cat­e­gories A+B+C1 amount to 31.8 mil­lion tons.

The Novopoltavske deposit con­tains rare met­al-apatite ores, the main ore com­po­nent of which is car­bon­atites. In com­plex car­bon­atite ores, the aver­age phos­pho­rus anhy­dride (P₂O₅) con­tent is 5.2%, while apatite con­cen­trate after enrich­ment con­tains up to 37% P₂O₅ and 1.45% rare met­als. The ores in this deposit are rep­re­sent­ed by dense, coarse-grained apatite-car­bon­ate for­ma­tions, includ­ing cal­cite and dolomite rocks with admix­tures of olivine, pyrox­ene, amphi­bole, and phl­o­go­pite. In the upper hori­zons, loose apatite-sil­i­cate vari­eties of car­bon­atites are devel­oped. Apatite is the most sta­ble min­er­al that accu­mu­lates in the weath­er­ing crust. In car­bon­atites, it occurs as scat­tered grains 3–5 mm in size, sol­id aggre­gates in con­tact zones with phen­ites, and in vein zones as long pris­mat­ic crys­tals.

In cal­cite and dolomite-cal­cite car­bon­atites, col­or­less, green­ish, and bluish-green apatite pre­dom­i­nates. In dolomite car­bon­atites, apatite of yel­low, brown-red, or green­ish-gray col­or occurs. The total ore reserves in the Novopoltavskoye deposit amount to 791 mil­lion tons, with an aver­age P₂O₅ con­tent of 5.2%.

Uses of apatite

Apatite is the main raw mate­r­i­al for the pro­duc­tion of min­er­al fer­til­iz­ers, in par­tic­u­lar super­phos­phate, ammophos, diammophos, and nitrophos­ka, which pro­vide the soil with the phos­pho­rus nec­es­sary to increase crop yields. In the chem­i­cal indus­try, apatite ores are processed into phos­phor­ic acid, which is used not only for fer­til­iz­er pro­duc­tion, but also in the food indus­try (food addi­tives, bev­er­ages), phar­ma­ceu­ti­cals, deter­gent pro­duc­tion, and water purifi­ca­tion. Burn­ing apatite with car­bon pro­duces ele­men­tal phos­pho­rus, which is used in the pro­duc­tion of match­es, explo­sives, met­al­lur­gy, semi­con­duc­tors, and the glass indus­try. Phos­phates obtained from apatite are also includ­ed in feed addi­tives for live­stock, which improve the growth and devel­op­ment of live­stock.

In addi­tion to the pro­duc­tion of min­er­al fer­til­iz­ers, phos­phates, phos­pho­rus, and phos­phor­ic acid, apatites are wide­ly used in oth­er indus­tries. In met­al­lur­gy, they are used as flux­es to reduce the melt­ing point of slags and improve refin­ing process­es.

In the chem­i­cal indus­try, apatite com­pounds are used as raw mate­ri­als for the syn­the­sis of var­i­ous organophos­pho­rus com­pounds, which are used in the pro­duc­tion of plas­tics, deter­gents, lubri­cants, and flame retar­dants. In addi­tion, apatites are used in the pro­duc­tion of spe­cial types of glass and opti­cal mate­ri­als, par­tic­u­lar­ly in laser tech­nol­o­gy. In bio­med­ical research, hydrox­ya­p­atite is the main com­po­nent of arti­fi­cial bone implants and coat­ings for endo­pros­the­ses, due to its bio­com­pat­i­bil­i­ty and abil­i­ty to pro­mote osseoin­te­gra­tion.

Thus, Ukraine’s apatite deposits con­tain sig­nif­i­cant reserves of phos­phate raw mate­ri­als suit­able for the pro­duc­tion of min­er­al fer­til­iz­ers and oth­er chem­i­cal indus­try prod­ucts. The main indus­tri­al inter­est is in ilmenite-apatite and car­bon­atite deposits, such as Strem­igorod­skoye and Novopoltavskoye. Their poten­tial can be real­ized through the intro­duc­tion of mod­ern enrich­ment tech­nolo­gies and the com­pre­hen­sive use of asso­ci­at­ed min­er­als. The devel­op­ment of domes­tic apatite min­ing can strength­en Ukraine’s raw mate­r­i­al inde­pen­dence in the field of phos­phate fer­til­iz­ers, reduce import depen­dence, and con­tribute to the devel­op­ment of the chem­i­cal indus­try.