焼成物および最終生成物である消石灰の粒子径と形状に及ぼす石灰石の焼成における有機ハロゲン化物雰囲気の影響について検討した.有機ハロゲン化物雰囲気を得るためには, 四塩化炭素または1, 1, 1, 2-テトラフルオロエタン (HFC134a) を焼成温度1000℃～1200℃で石灰石焼成中.空気と共に導入した.焼成物の収縮率, および焼成物を乾式消化して得た消石灰の45μmふるい通過量の割合について.4種類の石灰石を用いて測定を行い, 空気雰囲気焼成物の結果と比較した.
結果, 有機ハロゲン化物雰囲気下の石灰石焼成では, 石灰石の結晶粒径の影響が全体的に小さくなった.四塩化炭素雰囲気の場合は, 焼成物の収縮率が小さくなり, そして消石灰の微粉の割合が大きくなった.HFC134a雰囲気の場合は, 焼成物の収縮率が大きくなり, 消石灰の微粉の割合については影響が小さかった.焼成物や消石灰の粒子径と形状の変化についてもSEMにて観察した.さらに.石灰石の焼成中.有機ハロゲン化物中のハロゲンは焼成条件に応じて焼成物に固定化されることがわかった.この焼成方法は廃有機ハロゲン化物の処理を同時に行いながら生石灰や消石灰の物性を改質することができる方法として期待される.

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Al-containing low crystallized calcium silicate hydrate (C-S-H) was prepared by hydrothermal reaction at 95°C for 20 h, using water glass, calcium chloride and sodium aluminate as raw materials. The products were characterized by powder X-ray diffraction and NMR methods. and its ion exchange properties toward Ca²⁺, Mg²⁺, K⁺ and Li⁺ ions were studied.
C-S-H was predominantly formed and zeolites were hardly formed at the condition of H₂O/Na₂O =150. A type or X type zeolite was formed as by-products in the case of adding large amount of Al content at the condition of H₂O/Na₂O (molar ratio) = 50 and low Ca content. Cation exchange capacity (CEC) toward Ca²⁺ ion increased with increasing Al content of C-S-H. Ca²⁺ ion exchange was thought to correspond to the exchange reaction between Ca²⁺ and Na⁺ ion, some of which was introduced by Al substitution for Si and the other Na⁺ ion must be present connecting to broken bonds on C-S-H surface. Cation exchange reaction toward Mg²⁺ ion proceeded more slowly than that of Ca²⁺ ion. However its CEC was more than that of Ca²⁺ ion on many samples. CEC of Mg²⁺ increased with increasing Ca content of C-S-H. It was estimated that Mg²⁺ ion exchange reaction caused breaking of Ca-O bond in C-S-H structure. Amount of up-take of Mg²⁺ ion was roughly equal to the amount of release of Ca²⁺ and Na⁺ ions. Al containing C-S-H had CEC value more than 100 meq/100 g toward K⁺ ion but it was low value in the case of Li⁺ ion exchange.
It was suggested that Al containing C-S-H was composed of connecting and branching structure of silicate chain by NMR method.

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Hydroxyapatite (Ca₁₀ (PO₄) ₆ (OH) ₂; HAp) and β-tricalcium phosphate (β-Ca₃ (PO₄) ₂; β-TCP) are bio-compatible materials with bones and teeth. HAp is promising bone substitute materials for clinical applications because of chemical stability in vivo, while β-TCP has higher resorbability than HAp when the material is implanted in a bone defect. In the present study, HAp and β-TCP were soaked in the simulated body fluid, and then the reaction between the materials and the fluid was investigated in order to compare with the reaction in vivo. From the soaking test, carbonate hydroxyapatite was formed on the surface of HAp after 1 week, and then the amount of carbonate hydroxyapatite increased with increasing period of the soaking test. While β-TCP was not dissolved in the fluid, the carbonate hydroxyapatite was also formed on β-TCP after 12 weeks, and the amount of the precipitates on β-TCP was less than that on HAp. The reaction for HAp in vitro was similar to that in vivo, but the reaction for β-TCP in vitro was not similar to that in vivo.

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On the preparing process of Mg-containing synthetic whitlockite using a wet chemical method, synthesis of phosphate compounds having whitlockite structure replaced with Sr²⁺ ion or Ba²⁺ ion at Ca site and with other divalent metal ions at Mg site in the crystal was investigated.
As a result, whitlockite solid solutions (Mg- (Ca, Sr) W) replaced with Sr²⁺ ion at Ca site were produced in the pH regions from a neutral pH to a weak alkaline pH with mixed solution of Ca²⁺ and Sr²⁺ ions. However, synthetic barium whitlockite (Mg-BaW) and the whitlockite solid solutions (Mg (Ca, Ba) W) replaced with Ba²⁺ ion at Ca site were not produced with mixed solution of Ca²⁺ and Ba²⁺ ions. On the other hands, strontium whitlockite solid solutions (Mg- (Sr Ba) W) replaced with Ba²⁺ ion up to 90 mole% at Sr site were produced in pH regions from a weak alkaline pH to a high alkaline pH with mixed solution of Sr²⁺ and Ba²⁺ ions. Further, strontium synthetic whitlockite (SrW) contained Ni²⁺ ion, Co²⁺ ion, Fe²⁺ ion, Mn²⁺ ion, Zn²⁺ion or Cd²⁺ ion at Mg site was produced. Synthetic whitlockite prepared in this works defected metal ion at Ca site, was a nonstoichiometric composition.

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In recent years, because of the shortage in land disposal site, the waste burning at cement plant has become very important. And so-called chlorine bypass process is supposed to be the key technology. The main composition of the extracted dust in chlorine bypass is KCl. And the utilization or disposal of this dust is necessary to burn waste in a cement kiln.
In the previous paper, authors reported the influence of KCl on the alite hydration and on the hydrated products. But the total amount of chlorine in ordinary portland cement is limited at 200 ppm. in Japan Industrial Standard, in order to prevent the corrosion of reinforcing bars in concretes.
This paper deals with the hydration reaction of slag-KCl system which can contain larger amount of extracted dust. As a basic study to utilize lager amount of extracted dust in cementitious material, experiments were performed to know the phase composition change during the hydration of slag-KCl system in comparison with that of slag-Ca (OH) ₂ system. The hydration products in slag-Ca (OH) ₂ system were aluminum hydroxide gel and calcium silicate hydrate gel. And in slag-KCl system, Fridel's salt is formed in addition to the products in slag-Ca (OH) ₂ system. The CaO/SiO₂ ratio of calcium silicate hydrate gel produced in slag-KCl system were smaller value than that in slag-Ca (OH) ₂ system, because of the CaO consumption to form Fridel's salt.

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The fundamental experiment for the purpose of recovery of vanadium from oil burning ash, which was the valuable resources in Japan, was carried out. The following summarized the results.
Sulfuric acid was superior to aqueous ammonia as extraction media in the process of leaching vanadium ion from oil burning ash.
Precipitation ratio of vanadium compounds at room temperature was low. For example, the yield of vanadium compounds for 259200 s was no more than 60%. On the contrary, the precipitation rate increased at the higher reaction temperature and the yield reached up to approximately 100% at 80°C.
Initial concentration of vanadium ion was the important factor besides pH and reaction temperature. The higher initial concentration of vanadium ion enlarged the appropriate pH range for the precipitation. In the case of 16000 ppm of the initial concentration, the pH range was 2.0 to 2.8. It was wider than that of 4000 ppm or 8000 ppm.
The above results suggested that the higher initial concentration of vanadium ion, proper pH and higher reaction temperature were necessary to recover vanadium from oil burning ash efficiently.

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CO₂ fixation as formation of MgCO₃ with Mg (OH) ₂ is of particular interest because of the abundance of magnesium. We have studied an effect of crystallinity of Mg (OH) ₂ powder on their carbonation reactivity using synthesized Mg (OH) ₂.
Three types of Mg (OH) ₂ specimens were prepared using autoclave at 60°C, 120°C and 180°C, respectively. These were analyzed using X-ray diffraction, scanning electron microscopy, thermal analysis method and BET method. Difference of synthetic temperature has yielded variation of crystalinity of Mg (OH) ₂ to affect thermal properties and specific surface areas.
These specimens were suspended in the thermogravimetric analysis apparatus to perform isothermal thermogravimetric analyses at 350°C, 375°Cand 400°Cin CO₂ as carbonation experiments, respectively. Each specimen acquired the greatest amount of carbonate in final product at 350°C, at which the specimens synthesized at lower temperature, having lower, crystallinity and higher specific surface area, acquired a greater amount of carbonate. The result shows that Mg (OH) ₂ with lower crystallinity favored the formation of carbonate due to its high chemical activity and specific surface area.

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