【摘要】：我國是一個農(nóng)業(yè)大國,化肥的需求量十分巨大。目前,世界上生產(chǎn)鉀肥主要開發(fā)的是可溶性鉀資源。我國可溶性鉀資源貧乏,但是以鉀長石為主的不溶性鉀資源卻十分豐富。近年來,湖北省宜昌市夷陵地區(qū)發(fā)現(xiàn)儲量豐富的磷鉀伴生礦石,其主要礦物成分為鉀長石、氟磷灰石、石英、白云石、黃鐵礦等,P2O5含量為6~12%,K2O含量為5~9%,屬于中低品位礦。采用鹽酸酸浸此磷鉀伴生礦,可以在較低溫度下有效提取不溶性鉀,同時綜合利用磷、鋁、鈣等元素,具有重要意義。本文以宜昌市夷陵地區(qū)磷鉀伴生礦為原料,研究了鹽酸低溫酸浸磷鉀伴生礦提鉀工藝。通過比較添加不同助劑后的浸出率,選擇對鉀浸出效果有很大促進的氟化鈣作為助劑。通過單因素實驗探討了粒度、反應(yīng)溫度、鹽酸質(zhì)量分?jǐn)?shù)、浸出時間、原料比、鹽酸用量、攪拌速率對鉀浸出率的影響。并以酸浸溫度(A)、反應(yīng)時間(B)、鹽酸質(zhì)量分?jǐn)?shù)(C)和鹽酸用量(D)四個工藝條件作為變量因子,以鉀元素的浸出率作為評價指標(biāo)Y,進行響應(yīng)面實驗。根據(jù)回歸模型得出最佳工藝條件為:磷鉀伴生礦質(zhì)量為20g,磨礦時間為15min,鹽酸質(zhì)量分?jǐn)?shù)為23%,反應(yīng)溫度為92℃,反應(yīng)時間4h,原料比為0.2g氟化鈣/g礦粉,鹽酸用量為80m L,攪拌速度為500r/min。模型預(yù)測在此條件下鉀元素理論浸出率為92.8%,實驗驗證浸出率為91.3%,模型誤差為1.64%。結(jié)合磷鉀伴生礦浸出實驗結(jié)果與XRF、XRD及SEM-EDS等分析手段對該反應(yīng)過程與機理進行了分析,得出磷鉀伴生礦-氟化鈣-鹽酸反應(yīng)具體過程為:首先,礦石中的氟磷灰石、白云石以及氟化鈣等容易被酸分解的成分較快地溶解,產(chǎn)生細(xì)小孔道;然后,在氟離子與氫離子的共同作用下,礦石顆粒外表面的鉀長石逐漸被侵蝕,同時礦石顆粒內(nèi)部的鉀長石也被通過孔道擴散進去的氫氟酸緩慢侵蝕。并且,由于內(nèi)擴散的影響,顆粒深處的鉀長石未被完全分解,夾雜在孔道之中,惰性細(xì)小顆粒也被吸附在大顆粒的孔道內(nèi)。反應(yīng)機理分析和計算擬合結(jié)果表明,浸出過程遵循化學(xué)反應(yīng)和內(nèi)擴散混合控制的未反應(yīng)收縮核模型。并求得中間坪、太陽山、殷家坪地區(qū)磷鉀伴生礦反應(yīng)過程的表觀活化能分別為34.01 k J/mol、34.40 k J/mol、30.67 k J/mol;表觀速率常數(shù)分別為Km=379.2e-4090.6/T、Km=472.5e-4137.4/T、Km=115.2e-3688.8/T。最終求得混合控制動力學(xué)方程數(shù)學(xué)表達式。在20g小型實驗基礎(chǔ)上,進行了200g級、875g級、42kg級的酸浸提鉀實驗,基本重現(xiàn)了小型實驗的結(jié)果,該提鉀工藝無明顯放大效應(yīng)。
[Abstract]:Our country is a big agricultural country, the demand for chemical fertilizer is very huge. At present, the main development of potash fertilizer in the world is soluble potassium resources. The soluble potassium resources in China are poor, but the insoluble potassium resources, which are dominated by potassium feldspar, are very rich. In recent years, rich phosphate and potassium associated minerals have been found in Yiling area, Yiling City, Hubei Province. The main mineral components are potassium feldspar, fluoroapatite, quartz, dolomite, pyrite, etc. The content of P2O5 is 6 ~ 12 ~ (12) K _ 2O and the content of K _ 2O is 5 ~ 9%, which belongs to medium and low grade ore. It is of great significance to use hydrochloric acid to leach the phosphorus-potassium associated ore effectively at low temperature and to make comprehensive use of phosphorus, aluminum, calcium and other elements. In this paper, phosphorus and potassium associated minerals in Yiling area, Yichang City, were used as raw materials to study the extraction process of phosphorus and potassium associated with acid leaching of hydrochloric acid at low temperature. By comparing the leaching rate of different additives, calcium fluoride, which greatly promoted the leaching effect of potassium, was selected as the additive. The effects of particle size, reaction temperature, hydrochloric acid mass fraction, leaching time, raw material ratio, dosage of hydrochloric acid and stirring rate on the leaching rate of potassium were investigated by single factor experiments. The reaction surface experiments were carried out using the four technological conditions of acid leaching temperature (A), reaction time (B), hydrochloric acid mass fraction (C) and hydrochloric acid dosage (D) as variable factors and potassium leaching rate as evaluation index Y. According to the regression model, the optimum technological conditions are as follows: phosphorus and potassium associated ore mass is 20 g, grinding time is 15 min, hydrochloric acid mass fraction is 23, reaction temperature is 92 鈩，

本文編號：2275725