A mineral composition is shown which contains a mixed solid phase of synthetic calcium and magnesium carbonates, formed of a crystallized calcic portion and a plate-like crystallized magnesian portion. The crystals of the calcic portion and those of the magnesian portion are aggregated in the form of composite aggregates. These aggregates themselves are at least partly agglomerated in the form of agglomerates. The calcic portion has at least one carbonate such as calcite or the mixtures of calcite and aragonite. The magnesian portion contains hydromagnesite in plate-like form. The aggregates are further formed of a calcic core on which hydromagnesite plates are aggregated. The mineral composition has defined thermal conductivity properties making it suitable for use as a building material

The present invention discloses the systems of producing calcium and magnesium carbonate from the Ca/Mg containing solution leached by a CO.sub.2-based hydrometallurgical process which includes: a precipitation reactor that the Ca/Mg containing leached solution is continuously added and fully mixed with the alkaline reagent at specific mole ratio into the precipitation reactor and the reactor also comprises a CO.sub.2 bubbling module where CO.sub.2 is captured and recirculated from the thermal decomposition process as needed; a solid-liquid separation unit that the treated slurry is treated by the solid-liquid separation unit to produce precipitated calcium and magnesium carbonate products where the recirculating water is recycled back into the precipitation reactor; a thermal decomposition unit that the calcium and magnesium carbonate products is calcined by the thermal decomposition unit to produce an alkaline reagent and the alkaline reagent is recycled back into the precipitation reactor for the next batch of reaction.

The present invention relates to a method for continuous removal of carbon dioxide, the method comprising the steps of: a) preparing an aqueous solution containing an amine-based compound and an acidic calcium compound; b) bringing a gas containing carbon dioxide to be treated into contact with the aqueous solution to prepare a calcium carbonate precipitate; and c) recovering the calcium carbonate and then adding a basic calcium compound to the residual aqueous solution, wherein after step c), step b) and step c) are repeatedly performed. The removal of carbon dioxide by the method of the present invention has advantages of requiring low energy and being capable of mineralizing and removing carbon dioxide at a fast rate without a separate time for induction.

A process for treating a sulfurous fluid to form gypsum and magnesium carbonate, whereby the sulfurous fluid is scrubbed with a sequestrating agent to yield a scrubbed fluid, gypsum and magnesium sulfate. The flue gas desulfurized gypsum is isolated from the magnesium sulfate solution by filtration or centrifugation. The magnesium sulfate is reacted with a carbonate salt to produce a magnesium carbonate whereby the reaction conditions are controlled to control the properties of the magnesium carbonate produced.

The current invention relates to methods of the recovery and re-use of minerals obtained from the combustion of the residues of a process to recycle paper.

A geomimetic process of sulfate replacement by mineralized carbonate, either in situ or ex situ, is used for mineral carbon sequestration and critical element recovery.

The present invention provides a method of mineralisation of carbon dioxide. The method comprises forming an alkaline in aqueous solution containing carbonate anions by dissolving the carbon dioxide and an alkali such as ammonia in water. Next, the method comprises mixing the alkaline aqueous solution with a water source (such as a connate/formation brine or produced water or industrial waste waters or re-constituted mineral-bearing waters) containing magnesium and calcium cations. A first product (e.g. PCC) containing calcium cations and carbonate anions is precipitated in a first precipitation step at a first pH (e.g. around pH7.5) and then a second product (e.g. nesquehonite (NQ) a type of PMC) containing magnesium cations and carbonate anions is precipitated in a second precipitation step at a second, higher pH e.g. around pH 9.5.

A mineral composition made from a mixed solid phase of calcium and magnesium carbonates, method of preparing same and use thereof. A mineral composition made from a mixed solid phase of calcium and magnesium carbonates, formed from a crystallized calcium portion and a crystallized magnesium portion in the form of platelets, the crystals of the calcium portion and those of the magnesium portion being aggregated in the form of composite aggregates, said aggregates themselves being at least partially agglomerated, said calcium portion comprising at least one carbonate chosen from the group consisting of calcite, aragonite and the mixtures thereof, said magnesium portion comprising hydromagnesite in platelet form, said mixed solid phase having a bulk density less than or equal to 250 kg/m.sup.3, and greater than or equal to 80 kg/m3, measured according to standard EN 459.2.

Process for preparing a mineral composition based on a mixed solid phase of calcium and magnesium carbonates, comprising a preparation, in an aqueous phase, of a suspension of a solid phase containing at least one calcium compound selected from calcium hydroxide, calcium carbonate and mixtures thereof and at least one magnesium compound selected from magnesium oxide, magnesium hydroxide, at least partially hydrated dolomite, and mixtures thereof, the weight of said solid phase being between 5% and 15% of the total weight of the suspension, a carbonation of said solid phase in suspension by injecting a gas containing CO.sub.2 into said suspension that is heated at a temperature of 55 C. to 90 C., at a flow rate of CO.sub.2 of 2.5 to 15 dm.sup.3/min/kg of said solid phase of the suspension, with a reduction of the pH of the suspension to a value of less than 9 and with a stabilization of the electrical conductivity of the suspension, the carbonation being stopped as soon as this stabilization of electrical conductivity is observed.

A composite powder containing microstructured particles obtainable by means of a method in which large particles are combined with small particles, wherein the large particles have an average particle diameter within the range from 0.1 m to 10 mm, the large particles comprise at least one polymer, the small particles are arranged on the surface of the large particles and/or distributed inhomogeneously within the large particles, the small particles comprise sphere-shaped precipitated calcium carbonate particles having an average diameter within the range from 0.05 m to 50.0 m, wherein the sphere-shaped calcium carbonate particles are obtainable by means of a method in which
a. a calcium hydroxide suspension is initially charged,
b. carbon dioxide or a carbon dioxide-containing gas mixture is introduced into the suspension from step a. and
c. resultant calcium carbonate particles are separated off,
with 0.3% by weight to 0.7% by weight of at least one aminotrisalkylenephosphonic acid being further added.

Preferred application areas of the composite powder encompass its use as additive, especially as polymer additive, as additive substance or starting material for compounding, for the production of components, for applications in medical technology and/or in microtechnology and/or for the production of foamed articles.

The invention therefore also provides components obtainable by selective laser sintering of a composition comprising a composite powder according to the invention, except for implants for uses in the field of neurosurgery, oral surgery, jaw surgery, facial surgery, neck surgery, nose surgery and ear surgery as well as hand surgery, foot surgery, thorax surgery, rib surgery and shoulder surgery.

The invention also provides the sphere-shaped calcium carbonate particles which can advantageously be used to produce the composite particles according to the invention, and the use thereof.