POLYPHOSPHORIC ACID CALCIUM MAGNESIUM FERTILIZER, POLYPHOSPHORIC ACID CALCIUM MAGNESIUM FERTILIZER PREPARED BY USING PHOSPHORIC ACID AND PHOSPHORUS TAILINGS AS RAW MATERIALS AND PREPARATION METHOD THEREFOR

The present invention relates to a polyphosphoric acid calcium magnesium fertilizer prepared by using phosphoric acid and phosphorus tailings as raw materials and a preparation method therefor. The polyphosphoric acid calcium magnesium fertilizer is prepared by using phosphorus tailings and phosphoric acid as raw materials. Based on P 2 O 5 , MgO and CaO, in the polyphosphoric acid calcium magnesium fertilizer: total phosphorus is 50-68%, effective phosphorus is 47-66%, total magnesium is 5-18%, effective magnesium is 4-15%, total calcium is 11-20%, effective calcium is 10-18%, and all are expressed in mass percentage. Based on P 2 O 5 , the polymerization rate of the polyphosphoric acid calcium magnesium fertilizer is ≥50%. The present invention also provides a preparation method for the fertilizer. The phosphorus in the product prepared by the invention has sustained-release properties. The fertilizer is well suited for crops requiring large amounts of calcium and magnesium.

Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process

Provided is a method for producing phosphoric acid and at the same time obtaining alpha-hemihydrate gypsum including: adding a phosphate rock powder and a part of dilute sulfuric acid into an extraction tank, carrying out an extraction reaction on same, separating a clear liquid from the obtained mixed slurry, sending the clear liquid, as a finished product phosphoric acid, into an acid storeroom, and transferring a separated solid, together with the rest mixed slurry, into a crystal transformation tank; and adding sulfuric acid and a crystal transformation agent into the crystal transformation tank, carrying out a crystal transformation reaction for 1.5-7.5 h at 60° C.-130° C., and solid-liquid separating the obtained mixed acid slurry, wherein the solid can be dried into a gypsum powder, or may be not subjected to a drying step and made into gypsum products such as gypsum boards, gypsum building blocks and gypsum members by directly adding water.

Method for producing wet-process phosphoric acid and by-producing alpha-hemihydrate gypsum and high-purity and high-whiteness alpha-hemihydrate gypsum

Provided is a method for producing wet-process phosphoric acid and at the same time obtaining alpha-hemihydrate gypsum as well as high-purity and high-whiteness alpha-hemihydrate gypsum, including: mixing phosphoric acid and phosphate rock powder and performing extraction reaction; adding sulfuric acid solution to continue the reaction so that 30% to 50% of calcium ions are generated into dihydrate gypsum; transferring the dihydrate gypsum to a crystal transformation tank; adding a crystal transformation agent and controlling the crystal transformation conditions to obtain 30% to 50% of normal hemihydrate gypsum; after separation, introducing phosphoric acid extraction solution containing other 30% to 50% of calcium ions in a form of calcium dihydrogen phosphate into decalcification reaction tank; adding sulfuric acid solution diluted by washing liquid and performing decalcification reaction; controlling the crystal transformation conditions and performing crystal transformation reaction to convert the solid into high-purity and high-whiteness alpha-hemihydrate gypsum.

Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process

Provided is a method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by a wet-process. The method comprises: first adding a phosphate rock powder and a part of dilute sulfuric acid into an extraction tank, carrying out an extraction reaction on same, separating a clear liquid from the obtained mixed slurry, sending the clear liquid, as a finished product phosphoric acid, into an acid storeroom, and transferring a separated solid, together with the residual mixed slurry, into a crystal transformation tank; and adding sulfuric acid and a crystal transformation agent into the crystal transformation tank, carrying out a crystal transformation reaction for 1.5-7.5 h at 60°C-130°C, and solid-liquid separating the obtained mixed acid slurry, wherein the solid can be dried into a gypsum powder, or may be not subjected to a drying step and made into gypsum products such as gypsum boards, gypsum building blocks and gypsum members by directly adding water thereto. The method can eliminate discharges of a phosphogypsum and an acid insoluble substance, reduce the content of phosphorus in gypsum, improve the utilization rate of phosphorus, make full use of the dilution heat of concentrated sulfuric acid, and realize energy saving and emission reduction.

Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process

Provided is a method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by a wet-process. The method comprises: first adding a phosphate rock powder and a part of dilute sulfuric acid into an extraction tank, carrying out an extraction reaction on same, separating a clear liquid from the obtained mixed slurry, sending the clear liquid, as a finished product phosphoric acid, into an acid storeroom, and transferring a separated solid, together with the residual mixed slurry, into a crystal transformation tank; and adding sulfuric acid and a crystal transformation agent into the crystal transformation tank, carrying out a crystal transformation reaction for 1.5-7.5 h at 60°C-130°C, and solid-liquid separating the obtained mixed acid slurry, wherein the solid can be dried into a gypsum powder, or may be not subjected to a drying step and made into gypsum products such as gypsum boards, gypsum building blocks and gypsum members by directly adding water thereto. The method can eliminate discharges of a phosphogypsum and an acid insoluble substance, reduce the content of phosphorus in gypsum, improve the utilization rate of phosphorus, make full use of the dilution heat of concentrated sulfuric acid, and realize energy saving and emission reduction.

Engrais à base d'acide polyphosphorique, de calcium et de magnésium, engrais à base d'acide polyphosphorique, de calcium et de magnésium préparé en utilisant de l'acide phosphorique et des résidus de phosphore en tant que matières premières et procédé de préparation associé

Polyphosphoric acid calcium magnesium fertilizer, polyphosphoric acid calcium magnesium fertilizer prepared by using phosphoric acid and phosphorus tailings as raw material and preparation method therefor

The present invention relates to a polyphosphoric acid calcium magnesium fertilizer prepared by using phosphoric acid and phosphorus tailings as raw materials and a preparation method therefor. The polyphosphoric acid calcium magnesium fertilizer is prepared by using phosphorus tailings and phosphoric acid as raw materials. Based on P 2 O 5 , MgO and CaO, in the polyphosphoric acid calcium magnesium fertilizer: total phosphorus is 50-68%, effective phosphorus is 47-66%, total magnesium is 5-18%, effective magnesium is 4-15%, total calcium is 11-20%, effective calcium is 10-18%, and all are expressed in mass percentage. Based on P 2 O 5 , the polymerization rate of the polyphosphoric acid calcium magnesium fertilizer is ≥50%. The present invention also provides a preparation method for the fertilizer. The phosphorus in the product prepared by the invention has sustained-release properties. The fertilizer is well suited for crops requiring large amounts of calcium and magnesium.

Reflow oven

The present application provides a reflow oven (100). The reflow oven (100) comprises a furnace (101) and a gas pipeline assembly (104, 106). The furnace (101) comprises a plurality of furnace chambers Li (i = 1, 2,..., n). The gas pipeline assembly (104, 106) comprises a plurality of gas sub-pipelines (104.i, 106.i) (i = 1, 2,..., n). The plurality of gas sub-pipelines (104.i, 106.i) are detachably connected in a series to form a gas passage. At least a portion of the plurality of gas sub-pipelines (104.i. 106.i) is connected to at least a portion of the plurality of furnace chambers Li such that the plurality of furnace chambers Li is connected to the gas passage.

Method for producing wet-process phosphoric acid and by-producing alpha-hemihydrate gypsum and high-purity and high-whiteness alpha-hemihydrate gypsum