Method for recovering phosphorus from waste bones

Abstract

The invention relates to a method for recovering phosphorus from waste bones, and belongs to the technical field of phosphorus resource recovery. Leaching phosphorus in the waste bones: roasting the waste bones at high temperature, converting phosphorus in the bones into inorganic phosphorus, and then leaching the roasted bones by adopting a leaching agent to obtain a phosphorus-containing solution; leaching magnesium in the dolomite: leaching the magnesium in the dolomite by adopting a leaching agent, and carrying out solid-liquid separation to obtain a magnesium-containing solution and calcium sulfate precipitate; and synthesis of struvite: mixing the obtained phosphorus-containing solution and the obtained magnesium-containing solution to obtain a mixed solution, adding ammonia water, fully reacting, and filtering to obtain a filter residue which is the target product struvite. The method is simple in process and convenient to operate, phosphorus in the waste bones can be extracted and converted into relatively high-value struvite through a full-wet process, and a foundation is laid for recycling of the waste bones.

Description

Technical Field

[0001] The invention relates to a method for recovering phosphorus from discarded bones, belonging to the technical field of phosphorus resource recovery. Background Art

[0002] Phosphorus resources are non-metallic resources of strategic significance. At present, phosphate fertilizers, yellow phosphorus, phosphoric acid, phosphides and other phosphate products are widely used in agriculture, chemical industry, medicine, food and other industrial sectors. For agricultural production, phosphorus resources are extremely important resources. Phosphorus is one of the essential elements for plant growth and development. It is not only a component of many compounds in plants, but also participates in various metabolic processes in plants in various ways. Modern agriculture has effectively increased grain production through the rational use of phosphate fertilizers, phosphorus-containing pesticides and other agents. Therefore, the sustainable development and utilization of phosphorus resources is directly related to world food security and human production development.

[0003] Nowadays, mining phosphate rock is the only way for humans to utilize phosphorus resources, and phosphate rock is a non-renewable resource. my country is an industrial power, and its phosphate rock production has ranked first in the world for several years. According to relevant reports, my country's proven phosphate reserves account for only 4.6% of the world's reserves. In the long run, my country's phosphorus resources may face a crisis of depletion in a few decades. Therefore, the reasonable recovery of phosphorus resources from waste is of great help to my country's phosphorus resource strategy. It can provide a solid guarantee for my country's industrial and agricultural production.

[0004] At present, it is a trend to recover phosphorus from waste or raw materials with high phosphorus concentration. The most commonly used phosphorus recovery technology is phosphate precipitation, which generates phosphate precipitates such as struvite, calcium phosphate, aluminum phosphate, and iron phosphate through rapid chemical reactions. However, the current phosphate precipitation method is mainly aimed at phosphorus-containing wastewater. For solid waste such as discarded bones, how to effectively recover phosphorus from discarded bones is a technical problem. Summary of the invention

[0005] In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a method for recovering phosphorus from discarded bones. The present invention destroys the original structure of the bones by roasting and converts them into inorganic phosphorus; then the phosphorus element is leached out with a leaching agent. Another mineral dolomite is taken and leached with a leaching agent to obtain a magnesium-containing solution. The phosphorus-containing leaching solution and the magnesium-containing solution are mixed, and ammonia water is added to adjust the pH value. After the reaction, struvite mineral, i.e., magnesium ammonium phosphate (MgNH4PO4), can be obtained. The recovery rate of phosphorus in bones can reach 93.42%, and the precipitation rate of magnesium in dolomite can reach more than 98%. The present invention is achieved through the following technical solutions.

[0006] A method for recovering phosphorus from discarded bones comprises the following steps:

[0007] (1) Phosphorus leaching from discarded bones:

[0008] The discarded bones are roasted at high temperature to convert the phosphorus in the bones into inorganic phosphorus, and then the roasted bones are leached with a leaching agent to obtain a phosphorus-containing solution;

[0009] (2) Leaching of magnesium from dolomite

[0010] The magnesium in the dolomite is leached with a leaching agent, and a magnesium-containing solution and a calcium sulfate precipitate are obtained after solid-liquid separation;

[0011] (3) Synthesis of struvite:

[0012] The phosphorus-containing solution obtained in step (1) and the magnesium-containing solution obtained in step (2) are mixed to obtain a mixed solution, and then ammonia water is added. After sufficient reaction, the mixture is filtered, and the filter residue is the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0013] The discarded bones in step (1) are discarded chicken bones, pig bones or cattle bones generated in various food industrial productions, and the discarded bones contain a large amount of elements such as phosphorus and calcium.

[0014] In the step (1), the high temperature calcination is 600° C. to 1000° C., and the calcination time is 1 h to 3 h.

[0015] In the step (1), the leaching liquid-to-solid ratio is 1:1 to 2.5:1 mL / g, and the leaching time is 60 min to 90 min.

[0016] In the step (2), the dolomite is a magnesium-containing mineral, the main component of which is magnesium calcium carbonate.

[0017] In the step (2), the liquid-to-solid ratio is 8:1 to 12:1 mL / g, and the leaching time is 30 min to 60 min.

[0018] The leaching agent is one of HCl, HNO3, H2SO4 or a mixed acid of several of them in any proportion.

[0019] In the step (3), the volume ratio of the phosphorus-containing solution to the magnesium-containing solution is 500:400 L / L to 1200:600 L / L.

[0020] In the step (3), the volume ratio of ammonia water to the mixed solution is 50-150:1000 L / L, the reaction temperature is 15-45° C., and the stirring speed is 100-400 rpm.

[0021] The concentration of the leaching agent in the above step (2) is 10wt%-15wt%.

[0022] The beneficial effects of the present invention are:

[0023] The method of the present invention converts phosphorus in waste bones into inorganic phosphorus by roasting, and then uses a leaching agent to leach phosphorus in the bones to obtain a phosphorus-containing solution. The leaching agent is used to leach dolomite to obtain a magnesium-containing solution. The phosphorus-containing solution and the magnesium-containing solution are mixed, and then ammonia water is added to adjust the pH, and the reaction temperature and stirring rate are controlled to prepare a struvite product.

[0024] The process of the present invention is simple and easy to operate. It can utilize a fully wet process to extract phosphorus from discarded bones and convert it into high-value struvite, laying a foundation for realizing the resource utilization of discarded bones. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD diagram of the discarded bone after calcination of the present invention;

[0026] Figure 2 is the XRD pattern of the struvite prepared in Example 1 of the present invention;

[0027] Figure 3 This is a SEM-EDS image of the struvite prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0029] The reagents or instruments used in this example without indicating the manufacturer are all conventional products that can be purchased through regular channels.

[0030] The synthesis of struvite is fully reacted and then filtered to obtain a filtrate. The concentrations of Mg and P in the filtrate are determined and the precipitation rate is calculated.

[0031] Calculation of phosphorus recovery: The recovery rate was defined as the ratio of the total phosphorus in the resulting struvite to the total phosphorus in the calcined bone.

[0032]

[0033] Example 1

[0034] The method for recovering phosphorus from discarded bones comprises the following steps:

[0035] (1) Phosphorus leaching from discarded bones:

[0036] The discarded bones (discarded chicken bones, containing 8.6wt% P) were roasted at 1000℃ for 3h to convert the phosphorus in the bones into inorganic phosphorus. Then, the roasted bones were leached with a leaching agent (50wt% H2SO4) at a liquid-solid ratio of 2.5:1mL / g and a reaction time of 60min to obtain a phosphorus-containing solution. The phosphorus leaching rate was 93.62%.

[0037] (2) Leaching of magnesium from dolomite

[0038] The magnesium in dolomite (dolomite is a magnesium-containing mineral, the main component of which is magnesium calcium carbonate, and the magnesium content is 12.4wt%) is leached with a leaching agent (H2SO4 solution with a concentration of 10wt%), the liquid-solid ratio is controlled to be 10:1mL / g, the reaction temperature is 25°C, the stirring speed is 300rpm, the reaction time is 60min, and after solid-liquid separation, a magnesium-containing solution and a calcium sulfate precipitate are obtained; the magnesium leaching rate is 98.68%;

[0039] (3) Synthesis of struvite:

[0040] The phosphorus-containing solution obtained in step (1) and the magnesium-containing solution obtained in step (2) are mixed in a volume ratio of 500:400 L / L to obtain a mixed solution, and then ammonia water (analytical grade, the volume ratio of ammonia water to the mixed solution is 100:1000 L / L) is added, the reaction temperature is controlled to be 25° C., the stirring rate is 300 rpm, the reaction time is 60 min, and after sufficient reaction, the mixture is filtered, and the filter residue is the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0041] In this embodiment, the magnesium precipitation rate is 99.82%, the phosphorus precipitation rate is 99.79%; and the phosphorus recovery rate is 93.42%.

[0042] The XRD pattern of the discarded bone after calcination in this embodiment is as follows Figure 1 As shown, from Figure 1 It can be seen from the figure that the main phase of the calcined bone is hydroxyapatite. The XRD pattern of the struvite prepared in this embodiment is as follows: Figure 2 As shown, it is proved that the present invention can indeed prepare struvite. The SEM-EDS image of the struvite prepared in this example is as follows Figure 3 As shown, from Figure 3 It can be seen that the main components of struvite are phosphorus, magnesium and nitrogen, and the content of impurity elements is relatively low.

[0043] Example 2

[0044] The method for recovering phosphorus from discarded bones comprises the following steps:

[0045] (1) Phosphorus leaching from discarded bones:

[0046] The same as Example 1, except that the muffle furnace was controlled to maintain a calcination temperature of 900°C, the other conditions remained unchanged; the phosphorus leaching rate was 92.47%;

[0047] (2) Leaching of magnesium from dolomite

[0048] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 98.75%; (3) Synthesis of struvite:

[0049] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0050] In this embodiment, the magnesium precipitation rate is 99.67%, the phosphorus precipitation rate is 99.72%; and the phosphorus recovery rate is 92.21%.

[0051] Example 3

[0052] The method for recovering phosphorus from discarded bones comprises the following steps:

[0053] (1) Phosphorus leaching from discarded bones:

[0054] The same as Example 1, except that the muffle furnace was controlled to maintain a temperature of 800° C. for calcination, the other conditions remained unchanged; the phosphorus leaching rate was 90.74%;

[0055] (2) Leaching of magnesium from dolomite

[0056] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 98.63%; (3) Synthesis of struvite:

[0057] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0058] In this embodiment, the magnesium precipitation rate is 99.58%, the phosphorus precipitation rate is 99.64%; and the phosphorus recovery rate is 90.41%.

[0059] Example 4

[0060] The method for recovering phosphorus from discarded bones comprises the following steps:

[0061] (1) Phosphorus leaching from discarded bones:

[0062] The same as Example 1, except that the muffle furnace was controlled to maintain a calcination temperature of 700° C., the other conditions remained unchanged; the phosphorus leaching rate was 90.70%;

[0063] (2) Leaching of magnesium from dolomite

[0064] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 98.72%; (3) Synthesis of struvite:

[0065] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0066] In this embodiment, the magnesium precipitation rate is 99.53%, the phosphorus precipitation rate is 99.66%; and the phosphorus recovery rate is 90.43%.

[0067] Example 5

[0068] The method for recovering phosphorus from discarded bones comprises the following steps:

[0069] (1) Phosphorus leaching from discarded bones:

[0070] The same as Example 1, except that the muffle furnace was controlled to maintain a calcination temperature of 600°C, the other conditions remained unchanged; the phosphorus leaching rate was 90.55%;

[0071] (2) Leaching of magnesium from dolomite

[0072] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.65%; (3) Synthesis of struvite:

[0073] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0074] In this embodiment, the magnesium precipitation rate is 99.48%, the phosphorus precipitation rate is 99.76%; and the phosphorus recovery rate is 90.33%.

[0075] Example 6

[0076] The method for recovering phosphorus from discarded bones comprises the following steps:

[0077] (1) Phosphorus leaching from discarded bones:

[0078] The same as Example 1, except that the roasting time was 2 h, the other conditions remained unchanged; the phosphorus leaching rate was 92.64%;

[0079] (2) Leaching of magnesium from dolomite

[0080] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.65%; (3) Synthesis of struvite:

[0081] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0082] In this embodiment, the magnesium precipitation rate is 99.74%, the phosphorus precipitation rate is 99.85%; and the phosphorus recovery rate is 92.5%.

[0083] Example 7

[0084] The method for recovering phosphorus from discarded bones comprises the following steps:

[0085] (1) Phosphorus leaching from discarded bones:

[0086] The same as Example 1, except that the roasting time was 1 h, the other conditions remained unchanged; the phosphorus leaching rate was 91.83%;

[0087] (2) Leaching of magnesium from dolomite

[0088] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.72%; (3) Synthesis of struvite:

[0089] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0090] In this embodiment, the magnesium precipitation rate is 99.56%, the phosphorus precipitation rate is 99.71%; and the phosphorus recovery rate is 91.56%.

[0091] Example 8

[0092] The method for recovering phosphorus from discarded bones comprises the following steps:

[0093] (1) Phosphorus leaching from discarded bones:

[0094] The same as Example 1, except that the liquid-to-solid ratio was controlled to 2.0:1 mL / g, the other conditions remained unchanged; the phosphorus leaching rate was 93.57%;

[0095] (2) Leaching of magnesium from dolomite

[0096] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.65%; (3) Synthesis of struvite:

[0097] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0098] In this embodiment, the magnesium precipitation rate is 99.74%, the phosphorus precipitation rate is 99.85%; and the phosphorus recovery rate is 93.43%.

[0099] Example 9

[0100] The method for recovering phosphorus from discarded bones comprises the following steps:

[0101] (1) Phosphorus leaching from discarded bones:

[0102] The same as Example 1, except that the liquid-to-solid ratio was controlled to be 1.5:1 mL / g, the other conditions remained unchanged; the phosphorus leaching rate was 93.81%;

[0103] (2) Leaching of magnesium from dolomite

[0104] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.71%; (3) Synthesis of struvite:

[0105] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0106] In this embodiment, the magnesium precipitation rate is 99.45%, the phosphorus precipitation rate is 99.42%; and the phosphorus recovery rate is 93.27%.

[0107] Example 10

[0108] The method for recovering phosphorus from discarded bones comprises the following steps:

[0109] (1) Phosphorus leaching from discarded bones:

[0110] The same as Example 1, except that the liquid-to-solid ratio was controlled to be 1.0:1 mL / g, the other conditions remained unchanged; the phosphorus leaching rate was 92.71%;

[0111] (2) Leaching of magnesium from dolomite

[0112] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.63%; (3) Synthesis of struvite:

[0113] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0114] In this embodiment, the magnesium precipitation rate is 99.69%, the phosphorus precipitation rate is 99.55%; and the phosphorus recovery rate is 92.29%.

[0115] Embodiment 11

[0116] The method for recovering phosphorus from discarded bones comprises the following steps:

[0117] (1) Phosphorus leaching from discarded bones:

[0118] The same as Example 1; the phosphorus leaching rate was 91.87%;

[0119] (2) Leaching of magnesium from dolomite

[0120] The process of leaching magnesium from dolomite was carried out according to the method in Example 1, except that the concentration of the leaching agent was 8wt%, and the other conditions remained unchanged. The results showed that the magnesium leaching rate was 97.46%;

[0121] (3) Synthesis of struvite:

[0122] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0123] In this embodiment, the magnesium precipitation rate is 99.26%, the phosphorus precipitation rate is 99.31%; and the phosphorus recovery rate is 91.24%.

[0124] Example 12

[0125] The method for recovering phosphorus from discarded bones comprises the following steps:

[0126] (1) Phosphorus leaching from discarded bones:

[0127] The same as Example 1; the phosphorus leaching rate was 92.06%;

[0128] (2) Leaching of magnesium from dolomite

[0129] The process of leaching magnesium from dolomite was carried out according to the method in Example 1, except that the concentration of the leaching agent was 12wt%, and the other conditions remained unchanged. The results showed that the magnesium leaching rate was 99.34%;

[0130] (3) Synthesis of struvite:

[0131] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0132] In this embodiment, the magnesium precipitation rate is 99.43%, the phosphorus precipitation rate is 99.24%; and the phosphorus recovery rate is 91.36%.

[0133] Example 13

[0134] The method for recovering phosphorus from discarded bones comprises the following steps:

[0135] (1) Phosphorus leaching from discarded bones:

[0136] The same as Example 1; the phosphorus leaching rate was 92.81%;

[0137] (2) Leaching of magnesium from dolomite

[0138] The process of leaching magnesium from dolomite was carried out according to the method in Example 1, except that the concentration of the leaching agent was 15wt%, and the other conditions remained unchanged. The results showed that the magnesium leaching rate was 99.34%;

[0139] (3) Synthesis of struvite:

[0140] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0141] In this embodiment, the magnesium precipitation rate is 99.43%, the phosphorus precipitation rate is 98.67%; and the phosphorus recovery rate is 91.58%.

[0142] Embodiment 14

[0143] The method for recovering phosphorus from discarded bones comprises the following steps:

[0144] (1) Phosphorus leaching from discarded bones:

[0145] The same as Example 1; the phosphorus leaching rate was 92.13%;

[0146] (2) Leaching of magnesium from dolomite

[0147] The process of leaching magnesium from dolomite was carried out according to the method in Example 1, except that the liquid-solid ratio was controlled to 8:1 mL / g, and the other conditions remained unchanged. The results showed that the magnesium leaching rate was 99.42%;

[0148] (3) Synthesis of struvite:

[0149] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0150] In this embodiment, the magnesium precipitation rate is 99.51%, the phosphorus precipitation rate is 99.46%; and the phosphorus recovery rate is 91.63%.

[0151] Embodiment 15

[0152] The method for recovering phosphorus from discarded bones comprises the following steps:

[0153] (1) Phosphorus leaching from discarded bones:

[0154] The same as Example 1; the phosphorus leaching rate was 91.97%;

[0155] (2) Leaching of magnesium from dolomite

[0156] The process of leaching magnesium from dolomite was carried out according to the method in Example 1, except that the liquid-solid ratio was controlled to be 12:1 mL / g, and the other conditions remained unchanged. The results showed that the magnesium leaching rate was 99.51%;

[0157] (3) Synthesis of struvite:

[0158] The process of synthesizing struvite was carried out according to the method in Example 1, and the filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0159] In this embodiment, the magnesium precipitation rate is 99.36%, the phosphorus precipitation rate is 99.38%; and the phosphorus recovery rate is 91.40%.

[0160] Example 16

[0161] The method for recovering phosphorus from discarded bones comprises the following steps:

[0162] (1) Phosphorus leaching from discarded bones:

[0163] The same as Example 1; the phosphorus leaching rate was 91.86%;

[0164] (2) Leaching of magnesium from dolomite

[0165] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.46%;

[0166] (3) Synthesis of struvite:

[0167] The process for synthesizing struvite was carried out according to the method in Example 1, except that the volume ratio of ammonia water to the mixed solution was 50:1000 L / L, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0168] In this embodiment, the magnesium precipitation rate is 99.73%, the phosphorus precipitation rate is 96.93%; and the phosphorus recovery rate is 89.04%.

[0169] Embodiment 17

[0170] The method for recovering phosphorus from discarded bones comprises the following steps:

[0171] (1) Phosphorus leaching from discarded bones:

[0172] The same as Example 1; the phosphorus leaching rate was 92.26%;

[0173] (2) Leaching of magnesium from dolomite

[0174] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.37%;

[0175] (3) Synthesis of struvite:

[0176] The process for synthesizing struvite was carried out according to the method in Example 1, except that the volume ratio of ammonia water to the mixed solution was 80:1000 L / L, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0177] In this embodiment, the magnesium precipitation rate is 99.64%, the phosphorus precipitation rate is 96.58%; and the phosphorus recovery rate is 91.87%.

[0178] Embodiment 18

[0179] The method for recovering phosphorus from discarded bones comprises the following steps:

[0180] (1) Phosphorus leaching from discarded bones:

[0181] The same as Example 1; the phosphorus leaching rate was 92.19%;

[0182] (2) Leaching of magnesium from dolomite

[0183] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.65%;

[0184] (3) Synthesis of struvite:

[0185] The process for synthesizing struvite was carried out according to the method in Example 1, except that the volume ratio of ammonia water to the mixed solution was 150:1000 L / L, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0186] In this embodiment, the magnesium precipitation rate is 99.61%, the phosphorus precipitation rate is 96.49%; and the phosphorus recovery rate is 91.72%.

[0187] Embodiment 19

[0188] The method for recovering phosphorus from discarded bones comprises the following steps:

[0189] (1) Phosphorus leaching from discarded bones:

[0190] The same as Example 1; the phosphorus leaching rate was 92.23%;

[0191] (2) Leaching of magnesium from dolomite

[0192] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.58%;

[0193] (3) Synthesis of struvite:

[0194] The process for synthesizing struvite was carried out according to the method in Example 1, except that the reaction temperature was controlled to 15° C., and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH 4 PO 4 ).

[0195] In this embodiment, the magnesium precipitation rate is 99.71%, the phosphorus precipitation rate is 96.66%; and the phosphorus recovery rate is 91.92%.

[0196] Embodiment 20

[0197] The method for recovering phosphorus from discarded bones comprises the following steps:

[0198] (1) Phosphorus leaching from discarded bones:

[0199] The same as Example 1; the phosphorus leaching rate was 91.68%;

[0200] (2) Leaching of magnesium from dolomite

[0201] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.49%;

[0202] (3) Synthesis of struvite:

[0203] The process for synthesizing struvite was carried out according to the method in Example 1, except that the reaction temperature was controlled to 35° C., and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH 4 PO 4 ).

[0204] In this embodiment, the magnesium precipitation rate is 99.82%, the phosphorus precipitation rate is 99.73%; and the phosphorus recovery rate is 91.43%.

[0205] Embodiment 21

[0206] The method for recovering phosphorus from discarded bones comprises the following steps:

[0207] (1) Phosphorus leaching from discarded bones:

[0208] The same as Example 1; the phosphorus leaching rate was 91.85%;

[0209] (2) Leaching of magnesium from dolomite

[0210] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.75%;

[0211] (3) Synthesis of struvite:

[0212] The process for synthesizing struvite was carried out according to the method in Example 1, except that the reaction temperature was controlled to 45° C., and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH 4 PO 4 ).

[0213] In this embodiment, the magnesium precipitation rate is 99.79%, the phosphorus precipitation rate is 99.69%; and the phosphorus recovery rate is 91.57%.

[0214] Embodiment 22

[0215] The method for recovering phosphorus from discarded bones comprises the following steps:

[0216] (1) Phosphorus leaching from discarded bones:

[0217] The same as Example 1; the phosphorus leaching rate was 92.03%;

[0218] (2) Leaching of magnesium from dolomite

[0219] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.64%;

[0220] (3) Synthesis of struvite:

[0221] The process of synthesizing struvite was carried out according to the method in Example 1, except that the stirring speed was controlled to 100 rpm, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0222] In this embodiment, the magnesium precipitation rate is 99.82%, the phosphorus precipitation rate is 99.75%; and the phosphorus recovery rate is 91.80%.

[0223] Embodiment 23

[0224] The method for recovering phosphorus from discarded bones comprises the following steps:

[0225] (1) Phosphorus leaching from discarded bones:

[0226] The same as Example 1; the phosphorus leaching rate was 92.17%;

[0227] (2) Leaching of magnesium from dolomite

[0228] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.83%;

[0229] (3) Synthesis of struvite:

[0230] The process of synthesizing struvite was carried out according to the method in Example 1, except that the stirring speed was controlled to 200 rpm, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0231] In this embodiment, the magnesium precipitation rate is 99.74%, the phosphorus precipitation rate is 99.67%; and the phosphorus recovery rate is 91.87%.

[0232] Embodiment 24

[0233] The method for recovering phosphorus from discarded bones comprises the following steps:

[0234] (1) Phosphorus leaching from discarded bones:

[0235] The same as Example 1; the phosphorus leaching rate was 91.86%;

[0236] (2) Leaching of magnesium from dolomite

[0237] The process of leaching magnesium from dolomite was carried out according to the method in Example 1. The results showed that the magnesium leaching rate was 99.78%;

[0238] (3) Synthesis of struvite:

[0239] The process of synthesizing struvite was carried out according to the method in Example 1, except that the stirring speed was controlled to 400 rpm, and the other conditions remained unchanged. The filter residue was the target product struvite, i.e., magnesium ammonium phosphate (MgNH4PO4).

[0240] In this embodiment, the magnesium precipitation rate is 99.74%, the phosphorus precipitation rate is 99.75%; and the phosphorus recovery rate is 91.63%.

[0241] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for recovering phosphorus from discarded bones, characterized in that It includes the following steps: (1) Phosphorus leaching from discarded bones: The discarded bones are roasted at high temperature to convert the phosphorus in the bones into inorganic phosphorus, and then the roasted bones are leached with a leaching agent to obtain a phosphorus-containing solution; (2) Leaching of magnesium from dolomite The magnesium in the dolomite is leached with a leaching agent, and a magnesium-containing solution and a calcium sulfate precipitate are obtained after solid-liquid separation; (3) Synthesis of struvite: The phosphorus-containing solution obtained in step (1) and the magnesium-containing solution obtained in step (2) are mixed to obtain a mixed solution, and then ammonia water is added. After sufficient reaction, the solution is filtered, and the filter residue is the target product struvite.

2. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: The discarded bones in step (1) are discarded chicken bones, pig bones or cattle bones generated in various food industrial production.

3. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (1), the high temperature calcination is 600° C. to 1000° C., and the calcination time is 1 h to 3 h.

4. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (1), the leaching liquid-to-solid ratio is 1:1 to 2.5:1 mL / g, and the leaching time is 60 min to 90 min.

5. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (2), the dolomite is a magnesium-containing mineral, the main component of which is magnesium calcium carbonate.

6. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (2), the liquid-to-solid ratio is 8:1 to 12:1 mL / g, and the leaching time is 30 min to 60 min.

7. The method for recovering phosphorus from waste bones according to claim 4 or 6, characterized in that: The leaching agent is one of HCl, HNO3, H2SO4 or a mixed acid of several of them in any proportion.

8. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (3), the volume ratio of the phosphorus-containing solution to the magnesium-containing solution is 500:400 L / L to 1200:600 L / L.

9. The method for recovering phosphorus from waste bones according to claim 1, characterized in that: In the step (3), the volume ratio of ammonia water to the mixed solution is 50-150:1000 L / L, the reaction temperature is 15-45° C., and the stirring speed is 100-400 rpm.

Images