re how to increase C3S & reduce freelime in clinker -Page 4 of 4

Hello XXX,

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At 0.8% SO3 in the clinker your sulphur input does not appear to be exceptionally high. (unless you have a kiln bypass system) 

What is the molar SO3/Alkali ratio of your clinker? 

At an SO3/Alkali ratio of 1, SO3 preferentially reacts with K2O and Na2O to form simple alkali sulphates. As the SO3/Alkali ratio increases, the excess SO3 forms calcium langbeinite (2CaSO4.K2SO4) which melts at oC and is stable up to oC.

At even higher SO3/Alkali ratios, SO3 next starts to become incorporated in the clinker minerals, particularly the silicates (up to about 2% with respect to C2S and ~0.5% with respect to C3S). It is only at very high SO3 levels and high SO3/Alkali ratios that any remaining SO3 is free to form anhydrite (CaSO4).

In my experience, anhydrite does not appear in industrial clinkers unless the total SO3 content of the clinker is greater than ~3% and the molar SO3/Alkali ratio is >3.6.  Therefore, I doubt that decomposition of CaSO4 is the cause of your increased free lime. However, I agree with Arthur that you should have your clinker microscopically examined to determine why the free lime is high. Microscopy will tell you if the free lime is due to inhomogeneity of the kiln feed, for example, or oversize particles of quartz or calcite, or decomposition of C3S due to very slow cooling, or underburning, or a host of other causes.

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Also, I don't think your idea of increasing the petcoke ratio in fuel from 80 to 90% is likely to reduce your free lime. This would increase the LSF of the clinker, since less coal ash would be incorporated into the clinker, potentially increasing the free lime further.

Is your free lime continuously high (ie in every sample), or does it 'spike' up suddenly at frequent intervals?   

Do the brown centres of your large clinker nodules appear underburnt or over-burnt?

Regards,

Ted.

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Embodiment Present inventor is through repetition test and performing creative labour, successfully developed can expand for multi-purpose high calcium ripe and preparation method thereof. The chemical reaction mechanism that high calcium expansive clinker is applied to other products is, grog and auxiliary material are manufactured to powder-like product, and with water mix, fCaO aquation becomes Ca (OH) 2, and strong heat release, produce volumetric expansion.The size expanding and the absolute content of fCaO are proportional.When f-CaO >=75%, the stress that this expansion forms is enough large, can breaking up rock, concrete structures, and produce the soundless demolishing agent of high efficiency of successful Multiple Type.When suitable minimizing clinker dosage, adjusting reduce f-CaO absolute content, this expansion can be controlled to optimum range, effective compensation concrete shrinkage, and produce the cement expansive material that successful full remuneration is shunk. For reach above-mentioned two kinds of uses simultaneously, principle of design of the present invention is as follows: The feature of grog provided by the present invention is that to take well-crystallized's fCaO be essential mineral, effective content>=75%; In addition, containing 8-12%C 3s, containing 8-13%C 4aF; And do not allow to exist C 3a mineral.Why do not allow C 3a exists, and to be the too fast aquation of soundless cracking agent in order preventing from manufacturing, to cause spray orifice; For the short loss of coagulating, cause slump of cement expansive material that prevents from manufacturing. In a kind of embodiment of the preparation method of grog of the present invention: first prepare high calcium expansion raw material, then use precalciner kiln mature calcined material.In raw material, the weight ratio of each raw material is Wingdale 95-98%, iron powder 2-5%; Require CaO>=54% in Wingdale, Fe in iron powder 2o 3>=70%; Do not allow to allocate into clay, bauxitic clay, gypsum etc. in raw material.In addition, Al in the raw material that use in the application 2o 3with Fe 2o 3bi Zhi≤0.64, to guarantee Al 2o 3only and Fe 2o 3form C 4aF and do not form C 3a, Fe 2o 3only form C 4aF and do not form CF.The present invention is why without clay, bauxitic clay, gypsum preparation raw material, be to guarantee there is higher fCaO effective content in the grog of preparation, and reduce while effectively preventing from calcining, skinning accident, effectively prevent the discharge of SO2 obnoxious flavour. It should be appreciated by those skilled in the art that when using limestone mine masonry to originate for calcium oxide, the calcium oxide content that it finally provides is relevant to calcium carbonate content and Wingdale grade wherein.In this application, iron powder refers to the iron ore through ore dressing.Iron ore is rhombohedral iron ore.Therefore, the present invention's raw material used this restriction can wait and be all following weight percent and define, the content of Wingdale is counted with CaO content: the content of 51.3-52.9%, iron powder is with Fe 2o 3content count 1.4-3.5%, each weight percent is all the gross weight based on Wingdale and iron powder.The distortion of foregoing description is all in spirit according to the invention. - ℃ of the suitable control calcining temperature of the present invention and liter weigh ± 50g/L, with being beneficial to fCaO, form good crystalline state, can as unslaked lime, not meet water and digest rapidly. In the present invention, in order to obtain the high calcium expansive clinker that meets above-mentioned requirements, calcining temperature is ± 20 ℃.For fear of mixing too much coal ash, and avoid producing reducing atmosphere, avoid or alleviate ring formation, must select the fat coal of ash content≤10%, volatile matter 30-35%, sulphur in ash content, alkali content should be low as far as possible. The device using in grog manufacture of the present invention does not have special requirement, can be rotary kiln, shaft kiln or tunnel furnace. Below in conjunction with specific embodiment, the present invention is described in more detail. The preparation of embodiment 1 high calcium expansive clinker Prepare the raw material of following mass percent: Wingdale 96%, iron powder 4%, wherein in Wingdale, the content of CaO is 54%, Fe in iron powder 2o 3content be 73%, Al 2o 3with Fe 2o 3ratio be 0.49, above-mentioned raw materials pulverizing, combined grinding are made to raw material, with precalciner kiln mature calcined material at ℃, calcining fuel used is coal, pit ash content is 9%, volatilizing is divided into 32%, and the mineral composition of resulting high calcium expansive clinker is as follows: the effective content 80% of fCaO; In addition, containing 9%C 3s, containing 11%C 4aF; And not containing C 3a mineral.The granular state of knot of this grog is 15mm, the heavy g/L of liter. Embodiment 2 Prepare the raw material of following mass percent: Wingdale 95%, iron powder 5%, wherein in Wingdale, the content of CaO is 60%, Fe in iron powder 2o 3content be 75%, Al 2o 3with Fe 2o 3ratio be 0.51, above-mentioned raw materials pulverizing, combined grinding are made to raw material, with precalciner kiln mature calcined material at ℃, calcining fuel used is coal, pit ash content is 10%, volatilizing is divided into 35%, and the mineral composition of resulting high calcium expansive clinker is as follows: the effective content 84% of fCaO; In addition, containing 10%C 3s, containing 8%C 4aF; And not containing C 3a mineral.The granular state of knot of this grog is 20mm, the heavy g/L of liter. Embodiment 3 Prepare the raw material of following mass percent: Wingdale 98%, iron powder 2%, wherein in Wingdale, the content of CaO is 62%, Fe in iron powder 2o 3content be 75%, Al 2o 3with Fe 2o 3ratio be 0.53, above-mentioned raw materials pulverizing, combined grinding are made to raw material, with precalciner kiln mature calcined material at ℃, calcining fuel used is coal, pit ash content is 8%, volatilizing is divided into 35%, and the mineral composition of resulting high calcium expansive clinker is as follows: the effective content 82% of fCaO; In addition, containing 12%C 3s, containing 10%C 4aF; And not containing C 3a mineral.The granular state of knot of this grog is 15mm, the heavy g/L of liter. One of application of embodiment 4 high calcium expansive clinkers With the high calcium expansive clinker that embodiment 1 obtains, manufacture high-grade soundless cracking agent.Decapacitation is produced I, the II of national Specification, outside the product of three models of III, the high heat beyond can also production standard, super I type, super III type product for extremely frigid zones; Expanded the Application Areas of product, specific product performance is in Table 1 Table 1 Two of the application of embodiment 5 high calcium expansive clinkers The full offset-type cement expansive material of manufacturing with the high calcium expansive clinker that embodiment 1 obtains, auxiliary material is sulfoaluminate clinker, Al 2o 3≤ 32%; Anhydrite, SO 3≤ 46%.Under standard test condition, in 7d water, limited expansion rate, all higher than standard index, can reach 5-10 * 10 -4, all>=0, compensation efficiency reaches 100% to the dry empty limited expansion rate of 21d.Shrinkage-compensating effect to the above high strength grade of C60 concrete is particularly outstanding, and the compensation efficiency of dry empty 28d reaches 80%～100%, during to an age period, still remains on more than 50%. The present invention is through practical proof, reliable, feasible.With high calcium expansive clinker provided by the invention, produce complete compensatory cement expansive material, swelling agent is for the reinforced concrete wall engineering of thick 40mm, long 400m, for sectional area 1m 2concrete filled steel tube engineering, for preparing cement based high-strength grouting material, for making the reinforced concrete member of self-stress value 1.2Mpa, all or success. The above embodiment is only the preferred embodiments of the present invention, and is not the exhaustive of the feasible enforcement of the present invention.For persons skilled in the art, any apparent change of under the prerequisite that does not deviate from the principle of the invention and spirit, it having been done, within all should being contemplated as falling with claim protection domain of the present invention.