Behaviour Of Calcium Silicate In Leaching Process

Materials and Structures (2011) 44:487–498 DOI 10.1617/s11527-010-9643-3 ORIGINAL ARTICLE Resistance to acid attack, abrasion and leaching behavior of alkali-activated mine waste binders Pacheco-Torgal Fernando • Jalali Said Received: 13 July 2009 / Accepted: 15 July 2010 / Published online: 24 July 2010 Ó RILEM 2010 Abstract This …

including surface area values obtained from different tech-niques, by proposing different structures for high- and low-density C-S-H. Clearly, this distinction is important if the leaching process transforms the high-density morphology of C-S-H into low-density product with a large specific surface area.

Advanced Engineering Materials: Leaching Behaviour of Heavy Metals from the Class C Fly Ash-Based Geopolymers

Cyanide Leaching process is the main method of extracting gold from the ore and the concentrate in modern time. ... behaviour of calcium silicate in leaching process;

How to assess the long-term behaviour of a mortar submitted to leaching? ... leaching process is ... medium in which the main solid phases are Calcium Silicate ...

THE RECOVERY OF MANGANESE AND GENERATION OF AV ALUABLE RESIDUE FROM FERROMANGANESE SLAGS BY ... leaching process have ... silicate phases and their leaching ...

Calcium leaching is a degradation process consisting in progressive ... Materiales de Construcción, ... properties of crystalline calcium-silicate ...

can probably accommodate some calcium, but a point is soon reached at which calcium silicate hydrate precipitates as a separate component. In the pozzolanic reaction, the alkali silicate gel forms in an environment rich in calcium, and so converts quickly into calcium silicate hydrate.

Calcium aluminate process (lime sintering process) is a method to leach alumina from iron-bearing bauxite, fly ash and alumina-containing slags [5?7]. In this process, iron- bearing bauxite is sintered with limestone at 1500 °C.

Grega & Domen, 2011 [11] examined the effectiveness of OPC, calcium aluminate cement-CAC, pozzolanic cement-PC and different additives in immobilizing Cd, Pb, Zn, Cu, Ni and As, in contaminated soil. The effectiveness was evaluated using leaching experiments, mechanical strength and geochemical modeling.

Calcium leaching of the cement paste is a degradation process consisting in progressive dissolution of the cement paste as a consequence of migration of calcium ions to the aggressive solution. It is therefore a typical example of a dissolution process in a porous matrix where some of the mineral phases of the paste dissolve in the interstitial pore …

Steelmaking Slags in Acetic Acid for Precipitated Calcium ... extracted from a natural calcium silicate mineral by leaching in ... natural calcium silicates by process

assessment of the nuclear waste disposal systems[1–6]. Calcium leaching dissolves phases such as portlandite, AFm and decalcifies amorphous calcium silicate hydrates (C-S-H) phases. These dissolution processes alter porosity and pore connectivity which in turn, affect transport properties and loss of strength [1–2].

the silicon to calcium ratio of 0.8, 1.5, 2.0 and 2.5, re-spectively. The four groups of samples were heated in air at 1,173 K, with a heating rate of 10 K/min and kept at 1,173 K for 2 h. In addition, the samples with silicon to calcium ratio of 2.5 were heated at 1,173, 1,273, 1,373 and 1,473 K for 2 h, respectively.

The two silicate phases of cement, tricalcium silicate and dicalcium silicate give C–S–H and calcium hydroxide (CH) as hydration products. The C–S–H gel being the main component of cement hydration is responsible for the strength and microstructure of …

The leaching process increases the permeability of the soil samples having gypsum content, but there is little perceptible change in the permeability of soil samples without gypsum. The permeability value of soil samples without gypsum content increased from 1.2 × 10 − 5 to 4.1 × 10 − 5 cm/s after 30 days of leaching.

Recently published articles from Hydrometallurgy ... Sulfuric acid baking and leaching of ... Effects of calcium oxide and ferric oxide on the process of alumina ...

... on the leaching behaviour of Portland cement pastes made ... of the calcium silicate ... is typical of a diffusion-controlled leaching process.

In the sinter process, the raw material is mixed with a calcium salt (usually CaCO 3 ) and soda (for the lime-soda process) then heated to high temperatures (~ 1150 °C or above). The elevated temperature allows the alumina content in the raw material converting to a soluble product as aluminates and the silica to insoluble calcium silicates.

International Journal of Environmental Pollution and Remediation ... production of calcium–silicate ... and Leaching Behaviour of Slag-cement and ...

microstructure on leaching behaviour. ... AFm and decalcifies amorphous calcium silicate hydrates ... Calcium leaching under natural conditions is a slow process.

leaching progress. Also, this phenomenon of concrete leaching is currently considered to be the key to long-term safety of nuclear structures. Therefore, purposes of this study are to investigate not only the property changes of calcium leached concrete but also, the structural behavior of the concrete members associated with leaching attack.

Leaching of cement paste leads to increase of macroporosity due to the dissolution of chemi-cal components, namely Calcium Silicate Hydrates (CSH), Calcium Hydroxides (CH) and Hy-drated Aluminates (HA). The consequence of this increase of macroporosity is a reduction of mechanical properties (Carde, 1996).

This process induces mainly a total leaching of Ca(OH){sub 2} and a progressive decalcification of C-S-H which leads to a gradient of C/S ratio in the leaching zone.

There are many studies dealing with the calcium leaching behavior of ... and contents of CH and calcium silicate ... of 20 1°C for 24 h prior to mixing process.

BEHAVIOR OF SILICA IN ION EXCHANGE AND OTHER SYSTEMS ... Although calcium silicate is quite insoluble, ... product water makes this process undesirable.

Microwave-Supported Leaching ... is possibly due to the easy reaction of calcium silicate, while the slower calcium leaching ... In the microwave leaching process ...

Uranium processing: ... stable hexavalent state or be oxidized to that state in the leaching process. ... of the Ames process, calcium metal is substituted ...

Stability of calcium silicate in basic solution October 2003 · Transactions of Nonferrous Metals Society of China Mixture of CaO and Sio(2) was sintered at 1 200 or 1400 degreesC according to the mole ratio of CaO/SiO(2) of 1 or 2, and then calcium silicate was leached in pure caustic or soda solution.

Behavior of SiO2 during Leaching Process of Alumina Sinter ,- behaviour of calcium silicate in leaching process ,Some important secondary reactions during alumina sinter leaching have been analyzed thermodynamically,and the behavior of SiO2 in the process also investigated The results show that 2CaO-SiO2 can exist much more …

In the whole process, the leaching properties of alumina in smelting reduction calcium aluminate slag is the key part for aluminum in red mud recovering utilization. However, the studies on leaching behavior of alumina in calcium aluminate slag based on the red mud composition has not been reported so far.

A dynamic leaching study of the dissolution of low calcium to silicon ratio (C/S) calcium–silicate–hydrate (C–S–H) systems with initial C/S ranging from 0.2 to 0.6 has been undertaken. Dissolution was studied in demineralised water at 25 °C to a degree of leaching of 2.5 m 3 kg − 1.

By compensating for two NBOs, calcium also reinforces the silicate network against the hydrolysis reaction [64, 65] and in the residual alteration regime, it contributes to the formation of the alteration layer and to its passivation property [12,51] .

influence the calcium extraction efficiency [ 13 -14]. Calcium silicate or lime bound phase as (Ca,Fe,Mn,Mg)O can be the more reactive components for different steelmaking slag [ 12 ]. The calcium extraction efficiency from the slag can be improved through lowering the particle size of slag and solid to liquid ratio of the leaching system [ 14 ].

The effect of microstructure on the leaching behaviour of ... phases involved in the leaching process and to quantify the effects ... calcium silicate ...

The rapid calcium leaching step (up to 5 min) is possibly due to the easy reaction of calcium silicate, while the slower calcium leaching step (after 5 min) is owing to the difficult reaction of calcium ferroaluminates for the hydrolysis of iron and aluminum.

This reaction produces stable calcium silicate hydrates ... During the leaching process, ... International Journal of Pavement Engineering. Published online: ...

The goal of the present study was to optimize and validate a chemical process for ... of tri-calcium silicate ... and Leaching Behavior of ...