Kuva kuri Limestone n’ibumba, ukagera kuri portland unyuze kuri clinker: Ibyo wamenya ku nzira zinyurwamo ngo haboneke sima dukoresha mu bwubatsi
Sima ni ifu, ifarine ikomeye ikoreshwa mu bwubatsi, ikaba igikoresho gifasha mu guhuza ibindi bikoresho nk’umucanga n’amabuye kugira ngo bigire imbaraga n’ubudahangarwa.
Amateka yayo agaragaza ko ikoreshwa rya sima ryatangiye kera cyane: Abanyamisiri n’Abanyaroma ba mbere bakoresheje ibikoresho bisa na sima mu kubaka ibibumbano n’inyubako zikomeye. Nyuma y’aho, mu kinyejana cya 19, ni bwo habayeho iterambere rikomeye mu gukora sima ya kijyambere (Portland cement), yatumye ubwubatsi bugera ku rwego rwo hejuru.
Uyu munsi, sima ni igikoresho cy’ingenzi mu kubaka inzu zirmo n’imiturirwa igeretse ibinyacumi by’inzi, imihanda, ibiraro amateme n’ibindi bikorwa remezo, bituma ifatwa nk’umutima w’ubwubatsi bugezweho.
Ni muri urwo rwego iyi nkuru ya Virunga Tiday igamije gusobanura neza uburyo sima ikorwa, kugira ngo twumve aho ikomoka n’impamvu ikomeje kugira agaciro gakomeye mu iterambere ry’ibikorwa remezo.
Ni bihe bikoresho fatizo mu ikorwa rya sima
1. Limestone
Limestone ni ibuye rikize cyane kuri calcium carbonate (CaCO₃), iki kinyabutabire akaba aricyo shingiro mu ikorwa rya sima.
Iyo ritwitswe mu itanura rifite bushyuhe buri hagati ya 900°C na 1,000°C, ritanga calcium oxide (CaO) bahuz na silice (SiO₂) n’ibindi binyabutabire, bigatanga ibuye rikomeye rizwi ku izina rya clinker.
Uko limestone iba ifite ubuziranenge bwinshi (purity ya CaCO₃ iri hejuru ya 80–90%), niko itanga sima ikomeye kandi iramba.
Limestone kandi yoroshye gutwikwa no gusebwa (broyer) bigatuma yihuza n’ibindi bikoresho mu buryo bworoshye, bigatanga sima ifite imbaraga nyinshi.
Ibiye rya Limestone riboneka henshi ku isi, cyane cyane mu misozi yahoze ari inyanja, rikomoka ku bisigazwa by’ibinyabuzima byo mu mazi nka corals na mollusks. Mu Rwanda, riboneka mu duce nka Gishyita (Karongi) na Mpenge (Musanze) Rusizi ndetse no mu bice byinshi by’intara y’i Burasirazuba.
Ibumba (clay/shale)
Ibumba ni ibuye (roche) rikomoka ku materiaux yirunze munsi y’ubutaka cyangwa munsi y’amazi (sédiment), rikunze kuba rikize kuri silice (SiO₂), aluminium oxide (Al₂O₃), ndetse rikaba rifite n’utundi duce twa iron oxide (Fe₂O₃) n’ibindi bikoresho bito.
Nk’uko twabibonye hejuru, Iyo iri bumba rivanze na limestone mu itanura ku bushyuhe bwo hejuru (hejuru ya 1,400°C), rifasha mu gutanga ibinyabutabire bikomeye bigize clinker, ari byo bituma sima ikomera kandi ikaramba.
Uko ibumba riba rikize kuri silice na alumina, niko rifasha mu gukora sima ifite imbaraga nyinshi.
Ibumba riboneka henshi ku isi mu misozi igizwe na sediment. Mu Rwanda, riboneka mu bice bitandukanye by’igihugu, cyane cyane mu misozi ya Musanze, Gakenke, no mu Burasirazuba, aho riboneka mu buryo bworoshye.
Gypsum
Gypsum ni umunyu wa minerali ukize kuri calcium sulfate dihydrate (CaSO₄·2H₂O).
Mu rugendo rwo gukora sima, gypsum ntitwikwa nk’uko bikorwa kuri limestone cyangwa ibumba, ahubwo yongerwa ku clinker mu gihe cyo gusya kugira ngo igabanye umuvuduko wa sima mu kwiyumisha (setting time). Iyo gypsum itaba ihari, sima yahita ikomera vuba cyane, bikagora abayikoresha mu kubaka. Uko gypsum iba ifite ubuziranenge bwiza, niko ituma sima ikomera mu gihe gikwiriye, ikaba yoroshye gukoresha kandi ikaramba.
Gypsum iboneka henshi ku isi, cyane cyane mu butaka bwahoze ari inyanja cyangwa mu bice by’amakuzimu y’amabuye. Mu Rwanda, hari ahantu hagiye hagaragara gypsum mu bice by’Uburasirazuba ndetse no mu turere twa Bugesera na Nyagatare, ariko inganda zikenera kenshi kuyikura hanze kugira ngo zibone ingano ihagije.
Iron ore
Reka dusubiremo Iron ore mu buryo bwimbitse, nk’uko twabikoze kuri limestone, ibumba, gypsum na pozzolana:
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🔑 Akamaro ka Iron Ore mu ikorwa rya sima
– Igikoresho cyunganira: Iron ore rikize kuri iron oxides (Fe₂O₃ cyangwa Fe₃O₄).
– Uruhare mu itanura: Iyo yongerwa ku rugendo rwo gutwika limestone n’ibumba, iron ore itanga oxides z’icyuma zifasha mu guhuza neza ibinyabutabire bigize clinker.
– Imbaraga za sima: Oxides z’icyuma zongerera clinker ubushobozi bwo gukomera no kuramba, kandi zifasha mu kugabanya ingufu zikenerwa mu itanura.
– Ibara n’imiterere: Iron ore ituma clinker igira ibara ryijimye rihariye, kandi ikongera ubushobozi bwo gutwara ubushyuhe mu itanura, bityo igatuma rugenda neza.
– Iterambere ry’inganda: Nubwo iron ore idakenerwa mu ngano nyinshi nk’uko limestone cyangwa ibumba bikenerwa, ni igikoresho cy’ingenzi mu gutuma sima ya Portland igira ubuziranenge bwiza.
Aho riboneka
– Ku isi: riboneka mu misozi y’amabuye yicaye mu gihe kirekire (sédiment) cyangwa mu misozi y’amakuzimu, rikaba ari kimwe mu bikoresho bikomeye by’inganda z’icyuma n’iz’ubwubatsi.
– Mu Rwanda: hari ahantu hagiye hagaragara iron ore mu bice bya Nyamagabe, Rutsiro, ndetse no mu Burasirazuba, ariko inganda zikenera kenshi kuyikura hanze kugira ngo zibone ingano ihagije.