A compound represented by the general formula Li(Ti.sub.1-xZr.sub.x).sub.2(PS.sub.4).sub.3, wherein 0.01x0.25, and found to have high ionic conductivity; a use of the compound as a solid electrolyte, in particular in an all solid-state lithium battery.

A chemical phosphoric acid production unit, comprising a reactor for the production of phosphoric acid; a receiving device for receiving phosphogypsum obtained after filtration of phosphoric acid produced in the reactor; and a discharge system for discharging phosphogypsum from the receiving device. The discharge system comprises a chute of which the inlet is located inside the receiving device and arranged communicate with the receiving device, and a flap moveable around an axis of rotation and configured to open according to a predetermined angle corresponding to a predetermined section for the passage of a fraction of phosphogypsum through the inlet of the chute, and to close in order to prevent the passage of phosphogypsum into the chute.

A compound represented by the general formula Li.sub.1+xAl.sub.xTi.sub.2x(PS.sub.4).sub.3, wherein 0.1x0.75. The above compound has been found to have high ionic conductivity. Also, the use of the compound as a solid electrolyte, in particular in an all solid-state lithium battery.

A compound represented by the general formula Li.sub.1+xAl.sub.xTi.sub.2x(PS.sub.4).sub.3, wherein 0.1x0.75. The above compound has been found to have high ionic conductivity. Also, the use of the compound as a solid electrolyte, in particular in an all solid-state lithium battery.

An efficient method of producing a carbonate apatite is provided. The method comprises: a first step of calcining animal bone; and a second step of reacting a bone calcined product obtained in the first step with a basic carbonate compound.

An efficient method of producing a carbonate apatite is provided. The method comprises: a first step of calcining animal bone; and a second step of reacting a bone calcined product obtained in the first step with a basic carbonate compound.

A carbonate apatite highly containing carbonate groups, having excellent heavy metal adsorption capacity is provided. The carbonate apatite contains not less than 15.6% by weight carbonate groups, preferably contains at least one of copper (Cu), zinc (Zn), strontium (Sr), magnesium (Mg), potassium (K), iron (Fe), and sodium (Na), and preferably has a Ca/P molar ratio of not less than 1.5.

A carbonate apatite highly containing carbonate groups, having excellent heavy metal adsorption capacity is provided. The carbonate apatite contains not less than 15.6% by weight carbonate groups, preferably contains at least one of copper (Cu), zinc (Zn), strontium (Sr), magnesium (Mg), potassium (K), iron (Fe), and sodium (Na), and preferably has a Ca/P molar ratio of not less than 1.5.

To provide a method for producing a calcium carbonate block for medical use which is useful as a bone substitute or a bone substitute raw material needed in medical care, which is a method for producing a calcium carbonate block that satisfies the following desired properties: 1) the calcium carbonate block has excellent mechanical strength; 2) the calcium carbonate block can be produced by a simplified production method; 3) the calcium carbonate block contains no impurity; and 4) the calcium carbonate block has high reactivity.

A method for producing a calcium carbonate block, comprising a step of shaping a water-containing calcium hydroxide block and a carbonation step of immersing the calcium hydroxide block in a carbonate ion-containing aqueous solution.

To provide a method for producing a calcium carbonate block for medical use which is useful as a bone substitute or a bone substitute raw material needed in medical care, which is a method for producing a calcium carbonate block that satisfies the following desired properties: 1) the calcium carbonate block has excellent mechanical strength; 2) the calcium carbonate block can be produced by a simplified production method; 3) the calcium carbonate block contains no impurity; and 4) the calcium carbonate block has high reactivity.

A method for producing a calcium carbonate block, comprising a step of shaping a water-containing calcium hydroxide block and a carbonation step of immersing the calcium hydroxide block in a carbonate ion-containing aqueous solution.