• 시멘트 심포지엄
• /
• 1호
• /
• pp.23-30
• /
• 1973

In this paper, the reaction of the formation of portland cement clinker is reviewed. 1. When the specimen is heat-treated, the glassy phase melt with increasing temperature, and the starting materials are dissolved into the melt. After the melt is saturat

• 한국세라믹학회지
• /
• 제11권1호
• /
• pp.29-35
• /
• 1974

Effect of calcium sulfate and barium sulfate on the formation of portland cement clinker was studied by means of chemical analysis. DTA and X-ray diffraction analysis. In the presence of liquid phase, effect of the additives on the formation of tricalcium silicate was examined according to the reaction, 2CaO.$SiO_3$＋CaO$\longrightarrow$3CaO.$SiO_3$, which is the principal reaction in portland cement clinkerization, and optimum conditions in firing clinker concerning amount of additive, firing time and temperature were determined, and its kinetics was referred to. The experimental results are summerized as follow: (1) Appropriate burning temperature range of cement clinker is more limited as the content of calcium sulfate in clinker is increased. Amount of calcium sulfate, firing time and temperature in proper condition of clinkerization is related to each others. Being added suitable quantity of calcium sulfate, firing temperature of clinker can be lowered about $100^{\circ}C$. (2) When 3-5 mole% of calcium sulfate is added, firing time of 15-30 minutes at about $1380^{\circ}C$ is reasonable, and if the content is over7 mole %, firing for 1 hr. or more at $1350^{\circ}C$ is anticipated to be optimum condition. (3) In the reaction of tricalcium silicate formation, the role of barium sulfate as a mineralizer is similar to that of calcium sulfate, but the optimum firing temperature of cement clinker containing barium sulfate tends to be 20-$30^{\circ}C$ higher than that of clinker containing calcium sulfate. (4) When barium sulfate is used as mineralizer, 2-3 mole % of it to tricalcium silicate is recommended and if it is added more than this amount, free CaO is increased rapidly in clinker and alite formation is inhibited.

• 열처리공학회지
• /
• 제36권1호
• /
• pp.22-32
• /
• 2023

In general, when scrap is dissolved in an electric arc furnace, the amount of electric furnace steel dust (EAFD) generated is about 1.5% of the scrap charge amount, and the electric furnace steel dust collected by the bag filter is charged into the Rotary Kiln or Rotary Hearth Furnace (RHF), and the zinc component is recovered as crude zinc oxide, at which time a clinker of Fe-Base is generated. In this research, first, for the efficient resource conversion of electric furnace steel dust, a reduction and roasting experiment was conducted and the reaction kinetics was examined. As a result of the experiment, it was observed that the reduction and roasting reaction was actively conducted in the range of 1100~1150℃, and melting occurred in the range of 1250℃. In the past, this clinker was widely used as a roadbed material for road construction and an Fe-Source for cement production, but in recent years, it has been mainly reclaimed due to strengthening environmental standards. However, landfill treatment is by no means a desirable treatment method due to environmental pollution caused by leachate, expensive landfill costs, and waste of Fe resources. Therefore, in order to more actively recycle the Fe component in the clinker, first of all the clinker was pulverized into an optimal particle size, and anthracite and binder (starch) were added to the magnetic material obtained by specific gravity and magnetic separation for briquet. As a experimental results, it was possible to efficiently separate clinker as Fe component and other slag component by specific gravity and magnetic force. As a results of loading and dissolving the manufactured briquet clinker in an electric arc furnace, it was observed that the unit of power and production yield were clearly improved and the carbon addition effect in molten metal was also somewhat.

• 한국세라믹학회지
• /
• 제37권5호
• /
• pp.459-465
• /
• 2000

3CaO.3Al2O3.CaSO4(C4A3)clinker was prepared by solid state reaction and then its hydration property was investigated. C4A3 clinker was fired at various temperatures in the range of 700~135$0^{\circ}C$. The hydration of it was studied by XRD, DSC, Solid-state 27Al MAS NMR and SEM. According to the results, the Ca4A3 clinker was produced by reacting calcium aluminates with CaSO4 and Al2O3 and C4A3 was formed as a main phase after calcining at 120$0^{\circ}C$. The hydration products were mainly calcium monosulfoaluminate hydrate and Al(OH)3, and they were produced after 2hrs of hydration. However the hydration rate was about 74% at 3days.

• 한국세라믹학회지
• /
• 제34권9호
• /
• pp.949-956
• /
• 1997

With the increase of ZnO content, burnability of raw materials was improved and the formation of clinker minerals was accellerated. When ZnO was added 1wt%, the clinkering temperature was decreased about 30~5$0^{\circ}C$. As an increase of ZnO added, aluminate phase was decreased and ferrite phase was increased. When ZnO was added more than 3.0wt.%, the new phases, such as ZnO.Al2O3 and ZnO.Fe2O3 were formed. In the excess of amount of ZnO added, the decomposition of alite phase was intensed and the lamella structure in belite could not be observed due to the decomposition.

• 한국세라믹학회지
• /
• 제30권1호
• /
• pp.7-16
• /
• 1993

Effect of sulfate on the reactionof C3S formation in presence of clinker melt and its appearance in clinker were investigated, using (NH4)2SO4 and CaSO4 as sulfate sources. When (NH4)2SO4 and CaSO4 were added, both showed the similar results, 1.0wt% of sulfate could promoted the reaction of C3S formation, however for its content of more than 2.0wt%, the formation of C3S was prevented. Residual limit of sulfate to C3S formation is about 1.4wt%. Appearances of sulfate were C4A3l and CaSO4 in interstitial phase. For the addition of (NH4)2SO4 or CaSO4 of 20wt%~4.0wt%, C3S grains showed the hypertrophic growth. We might consider that, because sulfate reduced the surface tension and viscosity of the clinker melt, C3S crystals were precipitated below 140$0^{\circ}C$, and the crystlas of C3S were coalesced and linked in the same crystallographical direction with increasing temperature becuase of their rapid growth rate.

• 한국세라믹학회지
• /
• 제44권9호
• /
• pp.517-523
• /
• 2007

For the preparation of tricalciumaluminate $(C_3A)$ clinker, in traditional clinkering method using oxides and carbonates as a raw material, uneconomical repetition of burning have been necessary to avoid the melting of clinker by eutectic reaction in the system $CaO-Al_2O_3$. In this study, special starting raw materials for the clinker burning were prepared from a mixture of oyster shell and aluminium hydroxide by heating to $1100^{\circ}C$ and hydrating at $30^{\circ}C$. The starting raw materials, hardened body with weak hydraulic strength, were mainly composed of $C_3AH_6$ formed by resolution-precipitation mechanism of the system $CaO-Al_2O_3-H_2O$. By heating them, relatively pure $C_3A$ clinker could be obtained by one-time burning at the fairly lower temperature than that of conventional method. The easier formation of $C_3A$ clinker seemed to be caused by higher compositional homogeneity and stoichiometry of the starting materials, high surface area and crystallographic instability of the thermally decomposed products, and the catalytic effect of decomposed moisture on the early-stage crystallization of calciumaluminates. The basic hydration behavior of the clinker was also confirmed.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.11-16
• /
• 2002

The production of Portland cement involves maximum use of resources and energy, which leads to destruction of tile ecological environment, raising in serious environmental issues such as acid rain and the greenhouse effect. In order to combat the arising problems associated with Portland cement, it thus is necessary that a non-clinker cement should be developed. In this study, non-clinker cement is produced by blending granulate blast furnace slag with phosphogypsum as main materials, and small amounts of hydrate lime or waste lime as activators. This paper aims to investigate compressive strength according to various condition of mixing ratio, blame, W/C ratio and curing temperature. Compressive strength of non-clinker cement increases continuously according to increase in curing age and blain. Although the compressive strength is fairly comparable to that of OPC in the early curing age, it reaches a higher lever in the later age than that of OPC due to the optimum mixing ratio and the continuous reaction of slag and phosphogypsum. Results obtained from this study have shown that non-clinker cement could be used as a replacement of OPC.

• 공업화학
• /
• 제10권5호
• /
• pp.696-700
• /
• 1999

산업부산자원으로부터 유입되는 중금속이 시멘트 클린커 반응에 미치는 영향과 거동에 대하여 연구하였다. 원료물질에 Cu, Cd, Cr, Pb의 중금속 이온을 500 ppm 첨가하고 $1450^{\circ}C$에서 30분간 소성하여 소성성, 중금속의 고정농도 및 분배율에 따른 거동을 관찰하였다. 중금속의 고정농도는 Pb가 5% 이하로 가장 낮았으며 Cr은 약 85%로 가장 높게 나타났다. $1450^{\circ}C$에서 소성한 Cr을 첨가한 클린커는 free CaO의 함량이 3.41%로 소성성이 낮았으며 기타 중금속의 첨가는 클린커의 반응특성에 크게 영향을 미치지 않았다. 다만 중금속의 휘발로 인하여 클린커 조직에 거대 및 미세 기공이 다수 발생되었다. 클린커 원료에 첨가한 중금속중 Cd와 Cr은 주로 alite와 belite에 분배되었으나 Cu는 간극물질에 집중적인 분배율을 나타냈고 Pb는 휘발도가 높아 클린커 조직내에서 검출한계 내로 존재하지 않는 것으로 나타났다.

• 한국세라믹학회지
• /
• 제47권5호
• /
• pp.401-406
• /
• 2010

For the lower-temperature preparation of calcium monoaluminate(CA, C:CaO, A:$Al_2O_3$) clinker which is hard to synthesize purely within its melting point, an equimolar hydrate was obtained and then used as a starting raw material of clinker burning. The hydrate was prepared from a mixture of waste oyster shell and industrial aluminium hydroxide by heating to $1200^{\circ}C$, grinding and mixing with water. The hydrate was composed of amorphous aluminium hydroxide and $C_3AH_6$(H:$H_2O$) formed by resolution-precipitation mechanism of the system C-A-H. By heating the hydrate, nearly pure and porous calcium monoaluminate clinker was formed at $1400^{\circ}C$ which is fairly lower temperature than that of its melting point. The formation of calcium monoaluminate was performed mainly by the reaction between amorphous alumina and $C_{12}A_7$ caused by the decomposition of $C_3AH_6$. The immediate and earlier formation of $C_{12}A_7$ seemed to be accelerated by not only high surface area and instability of the thermally decomposed hydrate but also the catalytic effect of water decomposed from the hydrate. The final calcium monoaluminate clinker was very porous because of the influence of highly porous shape of the thermally decomposed hydrate.