CN1022556C - Feedstuff calcium hydrogen phosphate production by defluorination with gravity floatation - Google Patents

Abstract

The present invention relates to a copper circulation utilization technology in an ammonia synthesizing process, which belongs to inorganic phosphate industry. The technology of the present invention has the processes that hydrochloric acid or sulfuric acid is used for decomposing phosphate ore; lime cream is used for first stage neutralizing; fluoric impurities are separated through flotation by gravity according to the sedimentation speed difference of generated flocculent sediments and suspended materials; then, the processes of second stage neutralizing, aging, separating, etc. are carried out. The recovery rate of P2O5 in traditional feedstuff grade calcium hydrophosphate is improved from 30% to 80%.

Description

Feedstuff calcium hydrogen phosphate production by defluorination with gravity floatation

The present invention is a kind of method of utilizing feedstuff calcium hydrogen phosphate production by defluorination with gravity floatation.

The calcium hydrophosphate fodder production method of prior art, generally all adopt hydrochloric acid or sulfuric acid decomposing phosphate rock at home and abroad and carry out one section neutralization, defluorinate again after making acid hydrolysis solution, enter two sections neutralizations, filtration again, the precipitate and separate oven dry obtains calcium hydrophosphate fodder, " development of fodder additives secondary calcium phosphate " as the 21st volume third phase of Central China Normal University's journal (1987) report, use decomposing phosphate rock by chlorhydric acid, add the saturated aqueous common salt defluorinate, carry out one section neutralization and further defluorinate again, carry out two sections neutralizations thereafter, obtain calcium hydrophosphate fodder, feed P ₂O ₅The high energy of the rate of recovery reach 57.4%." the Production By Sulfuric Acid Process calcium hydrogen phosphate fodder craft discussion " of " phosphate industry " first phase report of and for example publishing in 1987, carry out defluorinate with adding sodium salt or sylvite in the technological process of sulfuric acid extraction phosphorus ore manufacturing calcium hydrophosphate fodder, its effect is all not good, can not reach the desired fluorine content of product standard, and draw a conclusion, use decomposing phosphate rock by chlorhydric acid, in its decomposed solution because of a large amount of Ca is arranged ⁺⁺Ion exists, and produces the calcium effect, i.e. " common-ion effcet ", P when making its defluorinate ₂O ₅Loss is big, then can't improve feed grade P ₂O ₅The rate of recovery.

The objective of the invention is to improve feed grade P for overcoming " common-ion effcet " ₂O ₅The rate of recovery, and make product surpass GB8258-87(table two) standard-required; Make P ₂O ₅The rate of recovery reach 80%, present method also comprises with sulfuric acid and extracts phosphorus ore, the defluorination process of preparation such as general calcium leaching liquid calcium hydrophosphate fodder.

The present invention is achieved by the following technical solution, and is raw material with ground phosphate rock, adds hydrochloric acid or sulfuric acid and reacts, neutralizes, precipitates, filters, separates, dries and make calcium hydrophosphate fodder.It is characterized by: make complex ion ACF in the decomposing solution ^3- ₆AL with APO ₄Precipitation is separated out, thereby discharges F ^-Ion is with CaF ₂Precipitation mode is removed, again reason " common-ion effcet " and be settled out a large amount of CaHPO simultaneously not ₄Lose, take off F one section neutralization ^-The time, the throw out that is generated has: AlPO ₄, FePO ₄, CaF ₂, Si(OH) ₄(H ₂SiF ₆The hydration H that hydrolysis goes out ₂SiO ₃H ₂O), CaHPO ₄, because they self solubleness and characteristic generate difform precipitation, AlPO ₄, FePO ₄, Si(OH) ₂, generate unbodied flocks, CaF ₂Generate the tiny settled suspended substance that is difficult to, because of the CaHPO of hydrolysis " common-ion effcet " generation ₄Be more macrocrystalline crystalline precipitate, the former three not free settling that easily suspends, the latter is then opposite.According to this characteristic: to be neutralized to pH be 2.0～2.5 with containing CaO7～10% milk of lime, utilize the settling velocity difference of precipitation, the suspended substance of generating, from top to bottom the suspended substance that generates is sucked vacuum filter with siphon mode, separate deleterious impurity in the feeds product, under the condition of not using defluorinating agent, make the P in the feeds product ₂O ₅The rate of recovery improves.

Chemical reaction equation with decomposing phosphate rock by chlorhydric acid is as follows:

（1）

Impurity in the ore also participates in reaction:

Because in acidic solution, iron, aluminium and hydrogen fluoride generate difficult dissociated complex ion in (3) and (4).

The steady FeF of Pk ^3- ₆The steady AlF of=15.4Pk ^3- ₆=19.75

So AlF ^3- ₆Than SiF ^3- ₆Much stable, as using sodium, sylvite to generate Na ₂SiF ₆, K ₂SiF ₆Precipitation mode is removed complex ion AlF ^3- ₆In F be very difficult.

If adopt in one section of the milk of lime and defluorinate, its reaction formula is:

Complex compound AkF as can be known from (10) formula ^3- ₆Raise with pH, separate out precipitate A lPO ₄And CaF ₂, simultaneously in equation (8) and (1) formula owing to a large amount of CaCl ₂Existence, promptly take place " common-ion effcet ", on the one hand CaCl ₂Existence, under this acidity (pH) condition, CaHPO ₄Solubleness reduce resultant Ca(H on the other hand ₂PO ₄) ₂Hydrolysis takes place, and its reaction equation is:

Generate a large amount of CaHPO to making ₄Precipitation makes P ₂O ₅Loss increases, and with impurity CaF ₂, AlPO ₄Deng being discarded together.

Fig. 1 is in a section of the embodiment of the invention and separation system figure;

Fig. 2 is the process flow sheet of the embodiment of the invention.

According to accompanying drawing invention is elaborated below:

Fig. 1, shown in Fig. 2, ground phosphate rock adds hydrochloric acid in decomposer (1) or sulfuric acid obtains acid decomposition liquid, acid decomposition liquid is put into one section neutralizing well (2), adding milk of lime stirs neutralization and generates suspended substance and precipitation, with siphon pipe (8) suspended substance in the neutralizing well (2) being sucked vacuum filter (3) consolidates, liquid separates, filtrate changes over to puts into ageing pond (5) ageing after two sections neutralizing wells (4) stir neutralization with milk of lime, change over to again vacuum filter (6) carry out solid liquid separate, filtrate is put into DFP pond (7) and is added the milk of lime clarification, separate, evaporation concentration obtains CaCl ₂, send the drying room oven dry to make calcium hydrophosphate fodder after the filter cake washing.

1: one section neutralization reaction of embodiment and separation system add acid decomposition liquid 5M as shown in Figure 1 in one section neutralizing well (2) ³(P ₂O ₅Content 50.17g/L), be neutralized to pH2.0～2.5 with milk of lime (containing CaO7～10%) stirring, required time 1.0～1.5 hours, continue to stir 30 minutes, placed 15 minutes, and the suspended substance in one section neutralizing well (2) was sucked vacuum filter (3) (filtration area 5M from top to bottom with siphon pipe (8) ³) on carry out Gu liquid and separate, required time 3 hours, 7M ³Volumes of filtrate, and residual about 1M ³Neutralizer (comprising throw out) adds 5M then successively ³The volume decomposed solution, and carry out cyclical operation according to aforesaid method, obtain 8M at every turn ³Volumes of filtrate, mean P ₂O ₅Content is 26.35g/L, and F content is 0.05g/L, P ₂O ₅: F=527: 1, the phosphorous recovery of this section is 84.03%.

Embodiment 2, shown in technical process Fig. 2,170～220g/LHCl solution of in the decomposer (1) of belt stirrer, preparing with hydrochloric acid and water, slowly add ground phosphate rock (composition sees Table one) by theoretical amount, adding the back stirred 40 minutes, decomposed solution is put into one section neutralizing well (2), the milk of lime that adds (containing CaO7～10%), be neutralized to pH2.0～2.5, continue to stir 30 minutes, carry out solid-liquid separation by the mode of embodiment 1, filtrate changes in two sections neutralizing wells (4), with milk of lime or later the DFP feed liquid be neutralized to pH4.5～5.0, continue to stir 30 minutes, put into ageing pond (5) ageing more than two hours, on vacuum filter (6), carry out solid-liquid separation, and wash filter cake with water, and filter cake send the baking room oven dry, and filtrate is put into DFP pond (7) and is added milk of lime and be neutralized to pH8～9, clarification, isolate the calcium chloride clear liquid in the overflow mode, send evaporation concentration workshop section system Calcium dichloride dihydrate or Calcium Chloride Powder Anhydrous, debris (DFP) is sent two sections neutralizing wells (4) back to.Divide and drop into 5.705 tons of ground phosphate rock altogether six times, obtain 2.3715 tons of finished product feedstuff calcium hydrophosphates.Six average feed grade P ₂O ₅The rate of recovery 79.43%, quality product and GB8258-87 standard be (seeing Table two) relatively.

Embodiment 3, and to the leaching of general calcium, sulfuric acid decomposing phosphate rock system sink calcium, owing to there not being " common-ion effcet ", but the existence of Al arranged, and separate out CaF ₂, pH improves then CaHPO ₄Loss.Adopt one section isolating method of neutralization of embodiment 1, pH is controlled at 3.0～3.5, and phosphorous recovery also can reach 80%, and fluorine content also can be reduced to below the mark requirement.

Table one, ground phosphate rock are formed

Form title P ₂O ₅CaO ₂MgO Al ₂O ₃Fe ₂O ₃F SiO ₂

Content % 23.89 43.83 7.99 0.71 0.41 2.68 1

Table two, product analysis result

Project P Ca AS heavy metal fluoride fineness

Content % is (with P ₂O ₅Meter) (in Pb) (in F) 400 μ m

Sample number

P-3????19.93????26.37????0.001????0.0003????0.10????99.5

（45.65）

GB8258-87????≥16.0????≥21.0????≤0.003????≤0.002????0.18????95

Remarks: above product analysis result is six comprehensive sampling results that feed intake

Claims (2)

1, a kind of method of feedstuff calcium hydrogen phosphate production by defluorination with gravity floatation is characterized by this method and comprises the following steps:

A. ground phosphate rock is added and fills in the decomposer of hydrochloric acid, stir 40 minutes, obtain acid decomposition liquid;

B. acid decomposition liquid is put into one section neutralizing well, added the milk of lime that contains CaO7～10%, be neutralized to pH2.0～2.5, stirred 30 minutes, placed 15 minutes;

C. from top to bottom the slip in one section neutralizing well is sucked vacuum filter with siphon mode, carry out solid-liquid separation, residual will the slurry with decomposed solution dissolving next time;

The filtrate that obtains among the D.C is put into two sections neutralizing wells, adds the milk of lime contain CaO7～10%, is neutralized to pH4.5～5.0, stirs 30 minutes, and ageing is also carried out solid-liquid separation in vacuum filter, and filter cake washes with water, send to then dry calcium hydrophosphate fodder;

The filtrate that obtains among the E.D is put into the DFP pond, adds milk of lime and is neutralized to pH8～9, and clarification is isolated the calcium chloride clear liquid in the overflow mode and carried out other processing again, and raffinate returns two sections neutralizing wells.

2, by the described method of claim 1, it is characterized by with sulfuric acid decomposing phosphate rock thing, in one section and pH be 3.0～3.5.

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